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Some geologic factors relating to the laboratory examination of recent sediments Toombs, Ralph Belmore 1953

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SOME GEOLOGIC FACTORS RELATING TO THE LABORATORY EXAMINATION OF RECENT SEDIMENTS by RALPH BELMORE TOOMBS A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCJfcNCE-i n the Department of GEOLOGY We accept this thesis as conforming to the standard required from candidates for the degree of MASTER OF SCIENCE. Members of the Department of Geology and Geography THE UNIVERSITY OF BRITISH COLUMBIA April , 1953 SOME GEOLOGIC FACTORS RELATING TO THE LABORATORY EXAMINATION OF RECEOT SEDIMENTS Abstract In selecting suitable procedures for the laboratory investigation of recent sediments, the f i r s t step suggested i s that of examining conditions in the geologic environment that influence sediment properties. This step i s illustrated by reference to the geologic history and physical features of a British Columbia fiord as a basis for assessing environmental conditions affecting the fiord sediments. Having inquired into the conditions sur-rounding the origin of sediments, the laboratory investigator i s better prepared to emphasize those procedures which w i l l provide the most s i g n i f i -cant types of data. In this project, a number of properties of recent sediments are investigated by physical, chemical and mechanical analyses, by the binocular, petrographic and electron microscopes, and by X-ray diffraction, spectro-scopy, and differential thermal analysis; techniques are selected on the basis of a study of the fundamental geologic principles relating to each sediment property. A number of s t a t i s t i c a l devices are employed in the presentation of data. Illustration i s given of the u t i l i t y of geologic data, as obtained i n the laboratory, to investigators i n the fields of s o i l mechanics, pedology and ceramics. The sediments examined during this study were obtained as bottom and core samples from Bute Inlet. They are best described as "rock flour": the sand fraction does not exceed 5% and the minerals are relatively unaltered; the clay-size fraction averages 23% but there i s no discernible clay mineral content. Mineralogically the sediments can be related, to a certain degree, to drainage basin geology. Information obtained to date on the Bute Inlet sedimentary environment suggests that sediments accumulating there are not characteristic of those which might be classified as source beds for petroleum. Y i i i C O N T E N T S Page Abstract v i i i PART I INTRODUCTION Nature And Scope Of Project 1 The Relationship Of Marine Geology To Other Marine Sciences 3 The Value of Recent Sediments Data 4 The Value Of Data Concerning Some Other Types Of Unconsolidated Sediments 5 In O i l Exploration 6 In Engineering Geology • • — 6 In Ceramics 7 In Pedology • 8 PART II THE GEOLOGIC ENVIRONMENT General — 9 The Formation Of Marine Sedimentary Deposits In Fiords 12 Geologic History: Coast Mountains, Fiord Development, Glaciation — — 14 The Terrigenous Origin Of Recent Marine Sediments'- 20 Other Origins Of Recent Marine Sediments 22 Land And Sea Transportation Of Sediments 24 Rate of Sedimentation 28 Types Of Recent Marine Deposits 31 PART III SOME GENERAL PHYSICAL AND CHEMICAL CHARACTERISTICS Comment — — — — — — — — 33 Color 35 Texture 37 Structure 39 Specific Gravity ; 41 i i Page Porosity • 42 Permeability 46 Moisture Content • 48 P l a s t i c i t y 51 Bonding Strength 53 Shrinkage and Swelling 54 Base Exchange ; 55 pH And Eh : 59 Organic Matter 6 l Calcium Carbonate ; — 65 Chemical Analyses 66 Compressibility •— 69 Some Conclusions Regarding Physical And Chemical Properties 69 PART IV MECHANICAL ANALYSIS Purpose And Uses 72 Preparation Of Sediments For Mechanical Analysis — - - - — 75 Mechanical Analysis Of The Sand Fraction 80 Hydrometer, Pipette, Decantation, Centrifuge And Microscope Methods — 86 Hydrometer Method 86 Pipette Method — — - 89 Decantation Method ; 89 Centrifuge Method 90 Microscope Size Analysis • 93 Some Limitations Of Mechanical Analysis 94 PART V MINERALOGICAL ANALYSIS General 96 i i i Page Binocular Examination : 98 Separation Procedures 100 Heavy Liquid Method 100 Isodynamic Separator 103 Infrasizer 105 Superpanner 106 Microsplitter 107 Preparation And Mounting 108 Mineral Determinations 115 Mineral Frequencies 121 Mineralogy And Microfossils Of Bute Inlet Sediments 123 Tabulation.Of Mineral Data, Bute Inlet Sediments 131 Shape And Roundness : — — — 137 Other Applications Of Mineralogical Methods —; 141 PART VI SOME SPECIALIZED ANALYTICAL METHODS Spectrographs Analysis 14-8 Electron Microscopy — — — — — 151 X-Ray Diffraction • 155 Differential Thermal Analysis 157 PART VII EVALUATION OF LABORATORY DATA Uses Of Statistical Measures 162 The Histogram, Simple Frequency And Cumulative Frequency Curves 165 Median Diameter, Sorting And Skewness Coefficients 168 A Statistical Comparison Of Mackenzie River And Bute Inlet Sediments - 173 A Trend In Statistical Analysis '• 174 iv Page PART VIII SUMMARY. A Suggested Laboratory Schedule 176 Some Characteristics Of Bute Inlet Sediments 179 ACKNOWLEDGMENTS : - 181 BIBLIOGRAPHY - 182 LIST OF TABLES Table No. Page I. Color description of Bute Inlet Sediments 36 II. Specific gravity and porosity determinations, Bute Inlet sediments 45 III. Moisture and shrinkage data - Bute Inlet sediments — 51 IV. pH values - Bute Inlet sediments 61 V. Size analysis - Mackenzie River sediments -- 82 VI. Data for siltometer operation 85 VII. Hydrometer analysis computations 91 VIII. Centrifuge size analysis computations 92 IX. Comparison of centrifuge and hydrometer size analyses • 93 X. Mineralogy - sand fraction - Bute Inlet sediments — 131 XI. Compilation of index o i l data 119 XII. Roundness indices - Bute Inlet sediments 139 XIII. Relation between particle size and sphericity :— 140 XIV. Weighted average sphericitives - Bute Inlet sediments 140 XV. Statistical data from cumulative curves - Bute Inlet sediments 171 XVI. Manganese and strontium content - Bute Inlet sediments • 151 v Table Ho. Page XVII. Tables for determination of d e t r i t a l minerals In Pocket LIST OF FIGURES Figure No. Following Page 1. Map of Bute Inlet In Pocket IA. Graphs showing relation between mineral frequencies and particle sizes, Bute Inlet sediments " IB. Sieve analysis data, sand fraction, Bute Inlet sediments " IC. Histograms based on sieve and hydrometer analyses, Bute Inlet sediments " 2. Map of drainage area, Bute Inlet 16 3. Mackenzie River sediments - sieve analysis 83 4. Siltometer and sieve analyses of a beach sand sample 85 5. Corrections for hydrometer readings 87 6. Cumulative curves - hydrometer and sieve analyses, Bute Inlet sediments 88 7. Weight accumulative curves - centrifuge analysis, Bute Inlet sediments 92 8. Calibration curves for index o i l s 116 9. Correction curve - Abbe Refractometer 118 10. Outline drawings for shape and roundness analyses, Bute Inlet sediments 139 11. Organic matter content, Bute Inlet sediments 171 12. Relation between median diameter and sorting factor, Bute Inlet sediments 171 13. Phi quartile skewness vs. median diameter, Bute Inlet sediments — 171 14. Trilinear diagram - size data, Bute Inlet sediments — - — 172 15. Schedule of laboratory operations 177 v i PLATES Following Page Some laboratory equipment for examination of recent sediments — 99 Photomicrographs - Bute Inlet sediments and a soil sample • 129 Photomicrographs - Bute Inlet sediments and a soil sample 132 Photomicrograph - Microfossils, Bute Inlet sediments 133 v i i / M SOME GEOLOGIC FACTORS RELATING TO THE LABORATORY EXAMINATION OF RECENT SEDIMENTS PART I I N T R O D U C T I O N Nature and Scope of the Project A classification of the sedimentary characteristics of any region or locality can only be worked out by the procedure of detailed field studies supplemented by appropriate laboratory investigations. The purpose of this report is to present an analysis of same basic geologic factors which are fundamental to the selection of suitable laboratory methods for the exami-nation of unconsolidated sediments, to outline some of these methods, and to illustrate the relation between principle and method by reference to the results ^ obtained from an examination of some recent marine sediments. The material made available for this study was in the form of bottom samples and 20-inch cores from Bute Inlet. Within the scope of the project certain conclusions are suggested which may supplement In a minor way the investi-gations of a geologic and oceanographlc nature which have been carried out in the general vicinity of Bute Inlet. In discussing geologic characteristics of unconsolidated sediments and ways of investigating these properties reference is also made to the value of the data so gained to the workers in Engineering Geology or Soil Mechanics, Oil Exploration, Pedology, and Ceramics. Although each of these workers examines sediments from a different angle, a l l are concerned with sedimentary materials and therefore can use geologic data as a starting point. The geologic study of recent sediments is pursued from the purely scientific point of view by collecting, examining, describing and corre-lating in order to determine origins and distributions; but i t also, by the - 2 -same process, makes available a body of knowledge for practical use in the field of applied sedimentation. Hence, i t was thought that some con-sideration should be given, in a study of geologic methods, to applied uses as well as to primary purposes of laboratory research data. In general, laboratory examinations of unconsolidated sediments which contribute to geologic knowledge center about five types of properties: physical, chemical, mineralogical, paleontological and bacteriological. Color, texture, structure, porosity, permeability, plasticity, shrinkage, moisture content, and specific gravity are some of the chief physical characteristics of a sediment. Complete chemical examination should include quantitative determination of calcium and magnesium carbonates, the iron oxides, organic matter, silica and alumina. Quantitative determinations of certain other chemical constituents may also be of value. In addition, measurements of pH and Eh and base exchange capacity, i f made under con-trolled conditions, are indispensable to the chemical approach. Mineralo-gical analysis has as its objective identification of a l l mineralogical components, Including the clay minerals, and description of mineral species as to particle size, shape, and surface texture. Paleontological exami-nation may require work on both a megascopic and microscopic scale. These four types of investigations - physical, chemical, mineralogical and paleon-tological - can be carried out In a fully equipped geology laboratory. The bacteriologist can contribute to a total appraisal of marine sediments by reporting on the micro-organisms present, as there is a direct relationship between bacteriological and organic matter content of sediments, and the state of this balance has an effect on such properties as pH and Eh. Diagenetic minerals may foim through the activities of bacteriaj conse-quently mineralogical history may also be influenced by bacteriological content. - 3 -In a complete research project on recent marine sediments, pro-vision must be made for gathering information on a l l five types of pro-perties. For other kinds of unconsolidated sediments, mineralogical data alone may be adequate. In this project, attention was given to mineralogy, and to some physical and chemical and paleontologies! c r i t e r i a . The Relationship of Marine Geology to Other Marine Sciences Si r John Murray l a i d the foundation for submarine geology through his studies of the bottom samples obtained by the Challenger Expedition, 1873-1876. American and German workers are today providing the lead i n sub-marine research. Current submarine geologic investigations are concerned with mapping topographic features of the sea bottom, studying the agencies which have formed these features, determining the types of sediments and gaining a knowledge of the processes of sedimentation. Much knowledge of the ocean areas, which cover 71% of the earth's surface, has been gained since the date of the voyage of H.M.S. Challenger. Oceanography embraces a l l phases of the study of oceans: con-figuration of ocean basins, movements of the water, physical and chemical properties of the water, their distribution, the processes that maintain this distribution, the organisms l i v i n g i n the ocean, the interrelation of the organisms and their environment and the interactions of the water with i t s bounding media, namely the atmosphere and the ocean floor. The study of the ocean, embracing as I t does s c i e n t i f i c investigations into many fie l d s , can be conveniently separated into three chief divisions: biological, pbysicochemical and geological. Although independent research proceeds i n each of these divisions, interrelationship can be illustrated by the fact that geologic studies of sediments accumulating i n a particular basin may assist i n an understanding of such chemical features of sea water as salini t y - 4 -and carbonate content and such biological characteristics as fluctuations in plankton content, whereas data on distribution of ocean currents may account for certain patterns of distribution of bottom sediments as well as variations in marine populations. The science of oceanography is broad in scope; i t depends for its advancement on the progress being made in each of its several divisions and in the synthesis of a l l products of research. Oceanography is important to Canada as this country has more coastline than any other country. During the past 50 years, greatest attention has been given in Canada to biological and physical-chemical aspects (Huntsman, 1949). Very l i t t l e has been published on the sediments or submarine geology of any of the Canadian coasts. The Value of Recent Marine Sedimentary Data It is only from a study of recent sediments that undistorted variation patterns can be obtained and be closely related to variation in the environmental factors. The pattern of modern environments and their sediments furnish the basis for evaluating ancient patterns and for eliminating or correcting for some of the post-depositional changes (Krumbein, 1945, p 1259). In addition to this projection of knowledge of present conditions Into the past, a fuller understanding of the laws of sedimentation is required,' and this can only come with more complete know-ledge of the transportation of debris in the sea and of the causes of various types of distribution patterns of sediments on the sea floor and in subsurface layers. Studies of recent marine sediments therefore aid in the formulation of scientific principles that describe the phenomena of sedimentation and these principles may ultimately lead to the development of diagnostic criteria - expressed in terms of mechanical, physical, chemical and mineralogical properties - for recognizing the origin of many - 5 -sedimentary rocks. Such sedimentary research has a value to the petroleum industry, which w i l l rely more and more on pure research work after the most obvious finds have been made. Revision of theories regarding the origin of continental shelves has come about through marine sediment investigations and submarine geologic work in general. Instead of being composed largely of sedimentary embank-ments built out over the deep ocean bottom, continental shelves are now known to have extensive outcrops of rock at a l l distances from the coast , and these rocks may date from Cretaceous times. The discovery of extensive areas of non-deposition of shelves and slopes also shows that unconformities do not necessarily imply withdrawal of the sea. Changes in currents could cause renewed sedimentation without having a transgressing sea. Continental shelf investigations, such as that of Shepard (1947), in throwing new light on the origin and nature of continental shelves have drawn attention to the greater possibilities of finding o i l along the continental margin than would have been deemed possible working on the hypothesis that the shelves were largely wave-built terraces. It i s now believed that nearly one half of the o i l remaining in'.the earth occurs in the sedimentary rocks beneath the ocean (Oceanography, 1951)• The plotting of sediment'distribution along a coast provides a basis, together with wave and current data, for planning engineering structures along beach fronts. Sedimentation studies of beach and harbour areas are important projects in the field of recent marine sedimentation. The Value of Data Concerning Some Other Types of Unconsolidated Sediments The term unconsolidated sediments i s meant to include not only Recent and Pleistocene sediments of a l l environments but any and a l l granular earth materials which cannot be called hard rock. Brief mention i s made here - 6 -of some of the classes of unconsolidated sedimentary materials and of the types of data which laboratory investigation, similar to that outlined in this report for recent marine sediments, can yield on these classes of sediments. In Oil Exploration.? Sedimentary petrology is an important branch of geological research undertaken in the development of oil,fields. Detailed examination of oil-well cuttings assists in the matter of corre-lation. Correlation data in turn helps to determine trend, size and closure of o i l traps. Furthermore, changes of facies in a member of a formation can generally be recognized by subsurface correlation methods. Maximum use of recovered oil-well cuttings can therefore be assured i f lithological examination i s detailed and complete. Correlations worked out by methods of sedimentary petrology involve use of the following features: horizon markers, for example an abrupt change in lithology; insoluble residues, especially where thick unfossilifereous limestone or dolomite occurs; mineral assemblages, as determined by characteristic minerals or mineral associations and as based on an examination of both mineralogy and physical properties of minerals such as size and roundness of individual grains; beds of volcanic ash, as unaltered material or altered to bentonite; fossils, both as assemblages and as index forms. These criteria indicate the importance of laboratory work in geological studies of o i l fields. In Engineering Geology.- Although there are transitional phases between laboratory work conducted to investigate geologic properties of sediments and that which i s carried out to determine engineering properties, each type of research has i t s own particular purpose. However, engineering usage of sediments is controlled by the geologic properties and by the processes which affect them. The construction engineer i s concerned with strength of sediments and the changes in strength under increased or de-creased stress whether i t be for highways, foundations, dams, tunnels, shore-line control projects, the prevention of landslides or the selection of proper material for use as a concrete aggregate. Geologic properties which determine the strength of unconsolidated sediments include such features as mineral composition - of which clay-mineral type i s possibly the most important mineralogical factor - grain size, porosity and per-meability, and water content. If an engineer has a geologic interpretation of these factors in terms of their implication to his particular.type of project, his own strength and load tests w i l l have more significance. In Part III the discussion of properties of sediments, which require laboratory investigation, includes some mention of the relation of geologic properties to engineering usage. In Ceramics.- Selection of sedimentary materials suitable for a ceramic use is most efficiently carried out by f i r s t considering these materials from the geologic point of view before embarking on long and ex-pensive ceramic tests. Once the field relations of a deposit have been, worked out and mineralogical composition of clay minerals determined by the geologist, the ceramist w i l l then be in a much better position to make appropriate selection of materials to meet his specifications. The geolo-gist's role in the evaluation of deposits of potential use to the ceramist therefore involves a study of the size, occurrence, origin and composition of the deposit, and in this work the laboratory provides valuable assistance in the determination of clay-mineral types as well as amounts, sizes and distribution of clastic particles and the general textural characteristics of the deposit. - 8 -The ceramist rates his materials ia terms of plastic limit, liquid limit, plastic index, suspension characteristics, bonding strength, drying, shrinkage and firing qualities. A l l of these properties are a function of such geologic factors as mineral composition and texture; hence geologic description of a deposit is fundamental to an appraisal of its poten-tialities as a source of ceramic materials. In Pedology.- Geological laboratory procedures can play a prominent part in pedological investigations. Mineralogical detail as obtained from microscopic and X-ray examinations combined with results of chemical and physical analysis may be used with effect In classifying and comparing soil profiles, in studying weathering processes, and in the correlation of soil types and parent material. The main contribution of geology to pedology is made through field investigations of Pleistocene and Recent deposits. Petrographic procedures afford a means of working towards a solution of some of the more complex soil classification problems. Incidental to the investigation of laboratory techniques for examining very fine-grained materials, some work involving mineral frequency determinations and the comparison of degree of alteration was carried out, during the course of this project, on mineral fractions of several soil i i samples and a record made of some suitable procedures. PART II THE G E O L O G I C E N V I R O N M E N T General Results of laboratory investigations nave l i t t l e meaning unless co-ordinated with data obtained from field studies of the geologic environ-ment which produced the sediments examined; conversely many conclusions re-garding environmental conditions must be supported by laboratory findings. In addition, selections of laboratory procedures are possibly most wisely made after some knowledge of source conditions has been gained. The two studies - field and laboratory - are therefore closely related and i t was considered that inddealing with a laboratory project reference must of necessity be made to the origin and occurrence of materials studied, and for the sake of completeness, results of the laboratory work should be placed in their environmental setting. As the sediments used to explore laboratory techniques were obtained from the British Columbia coastal area, description of the geological environment centers on the geological history and the physical features of a British Columbia fiord and adjacent lands, and the data gathered i s interpreted in terms of this environment. There are many environments of deposition. The chief locus of deposition of sediments i s the ocean; i t contains several distinct environ-ments related to supply of mechanical and chemical constituents, distance from land, character of water and configuration of the basin of deposition. Ocean environments include the floors of the deep sea, basins and geosyn-clines as well as continental slopes, continental shelves, beaches and bays In addition to ocean environments, many types of depositional environments are found on land. However, terrestrial deposits are less plentiful than marine deposits. Terrestrial sediments include river and delta deposits, accumulations in deserts, swamps and lakes, and sedimentary accumulations resulting from the agency of glaciation. Each environment, laud or sea, produces a sedimentary type which i s distinctive in many ways from sediments produced under other conditions. The history of a sedimentary deposit i s concerned not only with the environment of deposition: i t also includes the problems of source, nature of weathering of parent material, relationship of mechanical and chemical processes in erosion, and agents of transportation. A solution of these problems w i l l help to explain how environmental factors have conditioned grain-size distribution, certain chemical features and the mass physical pro-perties of a sediment, and also the nature of recognizable skeletal organic remains of plants and animals which lived in more or less specific adaptation to certain conditions of temperature, salinity and nutrient supply. A history of any deposit may be built up from i t s facies, the sum of litho-logical, structural and paleontological characters and their variabilities. Consequently a l l field and laboratory data is a contribution toward the final deduction of environment from facies which i s of greatest importance in geological investigation. There i s a close interrelation among the fundamental factors of environment: the shape of the land influences precipitation and flow of water with resultant affect upon erosion, transportation and deposition of sediments j water distribution influences ground shape by i t s erosion activity and by deposition, and is a factor in determining the type of weather j temperature has a marked influence on a l l other factors. The interplay of these fundamental factors might be described as the dynamics of sedimen-tation. However, i t i s not until the quantitative approach i s applied to - 11 -environment that a complete tmderstanding of the dynamics of sedimentary variation can be achieved. In addition to the progressive changes which occur, due to abrasion and selective sorting during erosion and transpor-tation, i n particle properties, variations occur in the deposited sediment in such mass properties as porosity, permeability, amount of faunal content, organic carbon content and many other features. By relating these changes to the physical and chemical conditions of the environment, as well as to energy transformations in the environment, a more dynamic picture of sediment behavior can be obtained. One approach to dynamic environmental studies can be made by adopting the "closed system" point of view, a system in which the bounding conditions and the total energy of the system are known and in which the transformation of matter may be observed and measured. Bays, beaches, lakes and sheltered ocean basin such as fiords make suitable areas for such studies. In each system bounding conditions may be defined by the limiting land forms, although any environment may be defined by arbitrary bounds, providing that the flow of energy and material across the boundary i s in-cluded in the study. The application of the closed system to environmental studies can be thought of in terms of a fiord, where the sources of the sediment, the means of carrying i t from i t s sources to points of deposition, and the means by which the carrying agent i s energized are, to a degree, a l l known. Thus the study of any environment includes a study of boundary con-ditions of the system, materials and energy of the system. In order to illustrate the importance of the consideration of en-vironmental factors to a laboratory study of sediments, this report in-cludes a description of the formation of sediments in a British Columbia fiord. To apply the concept of a closed system to the fiord described, complete data on wave and current directions and magnitudes and on stream - 12 -loads of the drainage system would be required; however sufficient infor-mation was gathered, as presented in Fart IV, V and VII to suggest that the coarsest and best-sorted sediments are associated with areas of high energy application. Reference i s made to the relation between sedimentary patterns and energy or dynamic processes because such a relation affords an insight into the combination of factors which produce sediments of given characteristics. If i t is eventually shown, through many studies of recent sediments, that patterns which reflect the dynamic conditions agree with patterns of sedi-mentary properties, then from ancient sediment patterns i t should be possible to reconstruct energy flow and energy losses within ancient environments. This would lead to a basis for more universal principles of sedimentation and increased u t i l i t y of sedimentary principles i n the various fields of applied sedimentation such as petroleum geology and soil mechanics. The Formation of Marine Sedimentary Deposits in Fiords Marine environments of sedimentation are classed on a depth basis as neritic, batbyal and abyssal. Nertic sea floors are not greater than 100 fathoms deep; batbyal parts of the ocean are intermediate in depth, 100 to 1000 fathoms; and the deep sea i s termed abyssal on the basis of a depth greater than 1000 fathoms. The fiord studied in this investigation i s Bute Inlet and i t s water could, on the basis of this classification, be described as neritic and bathyal as depths at the lower end of the fiord reach about 335 fathoms (See Figure I). The whole of the neritic environment of any water body is within the range of wave and current action; therefore the sediments may be only tem-porarily deposited and local unconformities or diastems are common. Streams bring major portions of their waters to the neritic environment and - 13 -suspended sediments come to rest there, temporarily or permanently de-pending on the position of the bottom with respect to a base level of de-position. The neritic environment i s also distinct from other marine environments in having the greatest mingling of waters of different types, the greatest decay of organic matter, the greatest circulation from bottom to top, the greatest variation in temperature and thus of carbon dioxide, the highest content of marine invertebrates and of plant l i f e . The neritic environment on the continental shelf and stretching out from a fairly uniform shore line therefore has definite features which set i t apart from the bathyal environment; however in a restricted area, such as a fiord, there are not the distinct differences between these two environments as are found along the open sea front. In the bathyal environment, waves and strong currents are of limited occurrence, and the sediments therefore remain in place. Here deposition takes place through settling from suspension, through a slow drift over the bottom from the neritic district, and from slumping. Chemical activity i s less intense than in the neritic environment. Poor circulation may permit development, over the deep bottom, of black muds rich in hydrogen sulphide. There is generally not as much l i f e , even in well aereated localities as there is within the neritic environment. This description, like that of the neritic environment, applies in part to Bute Inlet, and although i t can be said that the extremes of the depth ranges in the fiord do correspond with the appropriate classification, for the fiord as a whole characteristics are a composite of shallow and medium depth characteristics with possibly the bathyal feature predominating. The sediments transported to these environments have been formed a. through the direct or indirect agencies of physiography, distrophism and - H -climate. In a study of Bute Inlet sediments, physiography and climate are key factors, and 6ome knowledge of their nature i s of importance in deciding which laboratory procedures should be emphasized, especially in the matter of mineral identification work. Thinking generally of the processes of sediment accumulation, i t is important to note that sedimentation i s not going on everywhere in the sea, because of the existence of strong tidal and eddy currents which may be vigorous enough to prohibit a l l deposition. Diastema (interruptions in sedimentation) might be caused by elevation of the sea floor or sinking of sea level, increase in transportation capacity of waves and currents due to variations in climate, or lessening in supply due to alteration of river courses. Thus, in viewing the processes which take place during the accumu-lation of marine sedimentary deposits, attention must be given to the many variables in the factors of source, supply, transportation and deposition. The laboratory study of long marine sediment cores provides a means of assessing the extent of some of these variables, and, in combination with field data, of ascertaining their causes and of eventually building up a history of the deposit. Geologic History: Goast Mountains, Fiord Development, Glaciation To place a recent marine deposit in i t s proper geologic setting, i t s history must be carried back further than the immediate origin of the materials being deposited. To illustrate by reference to Bute Inlet sedi-ments, some consideration should be given to the main events in the formation of the Coast Mountains, to the development of the fiord and to the part that glaciation has played in the overall history of this area. As these sedi-ments also come under the general description of continental shelf sediments, mention should also be made of the origin of continental shelves. - 15 -Current theories of continental shelf origin have presented some entirely new concepts (Shepherd, 1948j Krumbein and Sloth, 1951). The island arc theory pictures islands along the coasts being separated by deep basins from the mainland j these islands were levelled by waves to a datum much below present sea level by low stands of the ocean during the ice stages. Sediments f i l l e d the troughs inside the former islands to give rise to broad shelves with rock and coarse sediment along the outer edges and finer sediments on the inside. In other areas, present submerged conditions may be due to drowning out, by the melting of glaciers, of downwarped glacial stage deltas. Other shelves may represent long-continued wave erosion of lands which produced wide platforms, with depth of the platforms related to glacial stage lowering of sea level. Glaciated coasts present the most clear-cut history of shelf development, as shelf deepening by movement of glaciers i s evident. The fiords of the British Columbia coast show evidence of the part that glaciation has played in shelf development in that region. Certain general events mark the development stages of British Columbia fiords. According to Peacock (1935), from early Paleozoic to mid-Triassic, volcanism was intermittent in the western Cordilleran Region. During Jurassic and Cretaceous times; the Region was subjected to horizontal compression forces from the northeast and southwest, and was invaded by granodioritic magmas which caused the formation of a high mountain belt. A system of vertical radial tension fractures and circumferential shear fractures developed as the region was bent into an outward curving arc. The present seaway owes i t s existence to a major longitudinal downfold which separates the Mainland Range from the Island Range. Towards the end of the Mesozoic, erosion modified the land expression slightly and then further com-pression from the northeast raised the formations to form the present Western - 16 -Belt of the Cordilleran Region. During this latter compression, a system of vertical shear fractures in northsouth and eastwest directions i s believed to have developed. This coast region, therefore, consists in the main of great thicknesses of massive andesitic lava flows and of volcanic breccias emplaced principally during Triassic times and metamorphosed to a degree in the Mesozoicj granitic rocks of the Coast Intrusives, possibly consisting in the main of granodiorite but having a wide range in com-position from acidic to basic; and sediments derived from these materials, Including the Pleistocene and Recent accumulations. Field studies have shown that the fiords of the British Columbia coast represent pre-glacial valleys which have been very much modified by the long continuing process of glacial erosion of the Pleistocene (Bancroft, 1913j Peacock, 1935; Davis and Mathews, 1944) • Fiord development possibly commenced during an erosion cycle following regional uplift of several thousand feet in the Pliocene. The valley development ceased during regional subsidence in the Pleistocene and during a regional uplift of some 600 feet in Recent times. Dr. W. H. Mathews believes that subsidence was essentially isostatic, coinciding approximately with maximum glaciation, but rebounding after deglaciation was under way. ^ The fiord system, which constitutes the lower part of the valley system, was considerably modified by intense valley glaciation in the Glacial epoch. The high fractured continental margin formed during late Cretaceous times gave rise to the reticulate pattern of the fiord system; pre-glacial erosion was responsible for the canyon-like form of the fiords and at least part of the disconcordances between the floors and main and tributary troughs. Erosional activity of Pleistocene ice i s considered to account for the depths of the fiord basins 1 Oral communication Scale 9 Miles To 1 Inch D a t a t a k e n frOfl Ce-»rfcell-Htw -R i v e r s Inlet Sheet, ::a;ior.-.l Topographic ~eri<?3. - 17 -below their rock threshholds, as well as some of the discordances between connecting basins. Present surface expression, to a large degree i s a result of this ice erosion. In picturing the development of British Columbia's fiords, therefore, i t is necessary to include three principle types of events: major earth movements, stream erosion and glacial erosion. The examination of bottom samples and cores of recent sediments from the fiords focuses attention on the question of the total depth of sediments in these fiords and the relative depths of Recent and Pleistocene deposits. Possibly cores of maximum recoverable lenths, in the neighborhood of 65 to 75 feet would provide direct evidence on this question from certain parts of the fiords, at least. Such evidence would have an interesting application in the computing of rates of sedimentation. Field studies, by Bancroft, Peacock and others, have indicated that the greater part of the glacial detritus was carried towards the edge of the continental shelf and beyond, and that today only a small part of i t underlies recent sediments. Extensive deposits of glacial drift constitute the islands found near the mouths of the fiords. Such islands as Savary and Hernando are thought to be terminal moraines. Terraces have not been noted in Bute Inlet, indicating that glaciers per-sisted within i t during the time that terraces were being formed along exposed shores. The same also holds for a l l of the larger mainland fiords. Field evidence thus suggests that the fiord bottom coverings are largely of recent marine materials with only a relatively small percentage of the total sediment accumulation being of Pleistocene origin. A typical British Columbia fiord i s a narrow arm of the sea bounded by precipitous mountain walls, extending far inland, and often having a series of tributary fiords, abrupt transverse elevations of the floor, a threshhold which i s rocky or moraine! in character, many small to medium-sized streams entering at the head and the sides of the fiord, and - 18 -considerable depths of recent sedimentary accumulations in the bottoms of the fiord basins. The fiords constitute a large portion of the British Columbia coast: approximately a 4.00$ increase in the length of the coast line has resulted from the formation of these features. For Bute Inlet in particular, the post-Mesozoic geologic history can be summarized thus: during the Pleistocene epoch, a glacier descended from the snow fields on to the western slopes of the Coast Mountains f i l l i n g a preglacial valley to a depth of between 4000 and 5000 feet; a certain amount of ice may also have come through the gap in the Range which i s now occupied by the Homathko River from the Cordilleran ice sheet; the major part of the glacier which emerged from Bute Inlet passed to the Gulf of Georgia, a part may also have gone towards Queen Charlotte Sound; the existing valley was widened and deepened (to as much as 2000 feet) during this glacial movement; the sea subsequently f i l l e d this enlarged valley and some post glacial uplift took place as well. Figure I shows the main geographic and geological features of Bute Inlet. The Homathko River flows into the head of the Inlet and i t in turn has i t s head waters in the Interior Plateau. The Southgate River flows from the southeast. The Homathko i s one of the largest rivers flowing into British Columbia fiords. With headwaters at an elevation of more than 2400 feet, i t flows in a southerly direction throughout i t s 84 mile course and i s about 300 feet wide where i t enters Bute Inlet. Its valley through the Coast Mountains varies from one quarter to three miles in width. It has many tributaries, the chief of which joins at a point 39 miles from i t s mouth. These tributaries are rapid flowing glacial streams and, as shown in Figure 2 , some of the glaciers descend almost to the Homathko valley. The Orford River i s similar to the Homathko, although i t s mountain drainage area is not as far removed from the sea and i t s valley i s V-shaped in places. - 19 -The drainage systems of the three main streams are i n general well-developed, the streams having reached a stage of maturity. A much younger series of smaller streams, occupying V-shaped valleys, i s also part of the Bute Inlet drainage pattern. These streams flow down steep slopes i n a succession of foaming rapids. A third class of streams Includes those of intermittent flow whose valleys are less distinct and smaller than the somewhat older V-shaped valleys. Geological detail on this area i s not available, but the main l i t h o -l o g i c a l features are plutonic rocks, predominantly quartz diorite but with abundant granite and granodiorite and some small masses of gabbro and hornblendite, highly altered sediments, and i n some l o c a l i t i e s such as at Bear Bay, a light mantle of glacial d r i f t . One or two bit s of detailed i n -formation can be added: Granite Mountain, 27 miles within Bute Inlet i s composed chiefly of medium-grained biotite granite of gneissoid texture (an important fact i n view of the large amounts of biotite found i n some of the bottom samples); at Clipper Point there are swarms of dark dykes which formed during the close of the Mesozoic invasion; at Alpha Bluff, wedges of schist of very small widths alternate with dykes of the same size giving rise to patches of schistose a r g i l l i t e ; and the general observation that a conspicuous roof pendant occurs on one side of the fiord and not on the opposite shore, which suggests the p o s s i b i l i t y of post-batholithie faulting or of a cutting off of the pendant during the period of magmatic intrusion. It Is thus seen, that although detailed information has not been gathered as yet on the Bute Inlet area, there i s sufficient general geographic and geological data available to establish the major characteristics of the area and to relate them to main developments i n the geologic history of the region. Oceanographic studies i n the f i o r d are thereby aided considerably. - 20 - . The Terrigenous Origin of Recent Marine Sediments In describing the bottom sediments of a fiord, i t Is of value to have in mind the mode of derivation of the sediments from the source rocks. The type of source rocks, climate, and topography are basic factors for?a consideration of the matter of terrigenous origin of recent marine sediments. The factor of glacial erosion i s a specific consideration in studies of British Columbia coastal sediments. The f i r s t matter to be examined i s the nature of the source rocks. Stability of the source rock material i s a key point. Information has been compiled (Pettijohn, 1950, p 380) to show the average order of loss of oxides and the stability of rock forming minerals, and this information has been,expressed in terms of a mineral stability series and a weathering index. Stability must be related to the manner in which rock destruction took place. Goldich (1938) stressed the nature of rock decomposition and i t s effect in terms of the source rock and studied these factors in relation to the mineral-stability series in weathering. In a study of recent marine sediments, particular attention can be given to the degree of alteration of felds pars. This alteration i s an expression of the process of hydrolysis which is considered to be the most important of the processes of rock de-composition. Rock disintegration i s a more important process of sediment formation than rock decomposition in the climatic and topographic environ-ment of the Coast Mountains. Consequently recent marine sediments found along the Coast would be expected to reveal evidences of the fact that mechanical disintegration outweighs chemical decomposition in the process of sediment production. As described in Part V, the minerals of Bute Inlet bottom samples do show evidence of only small amounts of chemical decom-position. These sediments can be described as the products of glacial - 21 -erosion and of mechanical breakdown of the rocks. Of particular interest in the subject of the mineralogy of marine sediments are the amounts and nature of the clay minerals. It is well to have in mind the processes by which clay minerals are produced. The common rock minerals consist of chains and networks of tetrahedra and octahedra whose corners are occupied by 0 and OH ions. The small interstices in the centers of the tetrahedra are occupied by silicon or aluminum ions. Aluminum, magnesium and iron ions are located inside the octahedra. The negatively charged 0 and OH polyhedra share corners and edges, and they are balanced and held together by positive cations, especially potassium sodium, calcium and magnesium. The interior of any crystal is in electrical equilibrium but the surfaces of many crystals are composed of ions whose valences are not completely satisfied. Upon the addition of water, hy-dration may occur during which water molecules are attracted to the unsatisfied valences of exposed silicon and aluminum. The exposed polarizing silicon and aluminum ions may then become surrounded with OH ions. At the same time hydrolyses, an exchange between exposed potassium ions of the lattice and H ions of the water may be going on. As a result of hydration and hydrolyses, the exposed oxygen tetrahedra become partial hydroxyl tetrahedra. Muminum tends to attract further OH ions and to assume i t s preferred octahedral configuration of hydroxyl ions. Coupled with the absence of stabilizing intertetrahedra K-ions, the surface layer becomes unstable and polyhedra peel off. Tetra and octahedral, liberated from feldspars and other rock minerals, aggregate among themselves to form clusters of colloidal size and upon aging the polyhedra orient themselves to definite crystal lattices, such as clay minerals of the montmorillonite i l l i t e and kaolinite groups. In viewing this process in terms of the field - 22 -conditions of climate topography and drainage in the Bute Inlet areas, i t would seem likely that the clay content of recent marine sediments of the fiord must of necessity be of very minor amount. Part VI summarizes the work done in this project to determine clay content. To conclude a discussion of the matter of the terrigenous origin of recent marine sediments, i t i s often the practice in detailed studies of these sediments to relate more or less precisely the sample studied to the approximate source area. The Bute Inlet sediments were found to have certain distinct characteristics and from the work done a pattern of distr i -bution based on these characteristics has- been partially worked out. However in order to utilize with effect mineral pattern distribution data to trace the processes of sedimentation, from i n i t i a l production of sedimentary particles at the source to final deposition, more detailed information of geology of the area and of the transportation agencies would be required. The present study has only indicated main source areas for the terrigenous sediments and the fact that these sediments constitute almost a l l of the recent marine sedimentary deposits. The importance of disintegration and of ice erosion (see Holmes, 1949) in the production of these sediments i s also apparent from mineralogical examination. Other Origins of Recent Marine Sediments In addition to sediments described as terrigenous in the sense that they result from erosion of continental rocks, there are four other major classes of sediments: organic, volcanic, cosmic or meteoric and magmatic. The latter three are of no importance in the case of Bute Inlet sediments. Volcanic materials have an important place in the study of some recent marine sediments, particularly in the examination of long cores where the detection of volcanic ash of known origin could be used in a method for - 23 -computing rate of sedimentation. Such a computation i s based on a com-parison of depths of volcanic ash layers to lengths of time since eruptions of the supplying volcano. Several instances are recorded in the literature demonstrating the use of this method. No volcanic ash layers were noted in Bute Inlet cores. The amount of decomposable organic materia! contained in marine sediments is of particular significance as practically a l l petroleum i s obtained from marine sediments and i t has formed from organic remains de-posited with the inorganic constituents. Organic matter is that portion of a sediment which has arisen through organic activity, and which contains carbon in any form other than as carbonates. Organic matter content tends to increase with decrease in grain size of sediments and with nearness to land, where the waters are usually more fertile in marine l i f e . The con-ditions favoring formation of sediments rich in organic matter are abundant supply of organic substance, relatively rapid rate of accumulation of inorganic materials of fine grained texture and limited supply or absence of oxygen. The most extreme development of such conditions may be found in basins and landlocked regions where stagnation exists. Based on information available on the physical features of the fiord basin and the waters and on the data gathered during this project, i t would seem unlikely, except possibly for one or two very small localities, that favorable conditions exist in Bute Inlet today for the formation of petroliferous sediments. Although the rate of sedimentation i s quite possibly a favorable factor, the factors of oxygen supply and organic matter supply, as known to date, do not appear characteristic of those said to prevail during the formation of source sediments. A definite opinion however could only be made after de-tailed studies of water samples, from various depths, particularly as to the dissolved oxygen content, phosphates, silicates, temperature, pH and - 24 -plankton content so that a correlation of the physico-chemical conditions with amount of plankton could be made. One study of this nature has been made (Garter, 1933) and the conclusions reached were that conditions for abundant plankton growth are much more favorable at the mouths of several British Columbia fiords and in the Strait of Georgia than towards the head of the fiords. As pointed out in Part III of the present report, a maximum value for the organic matter content was obtained for a sample from a point near the mouth of Bute Inlet and organic matter percentage was found to decrease with distance up the fiord. Many more organic matter analysis would, however, be required in connection with physico-chemical and plankton content studies in order to complete a study of petroliferous possibilities for these fiord sediments. Land and Sea Transportation of Sediments Interpretation of the characteristics of sediments must also be considered in terms of the environment of transportation in order to esti-mate the nature of changes that took place following removal from the source and prior to deposition. Certain general principles form a basis for a study of transportation effects. Changes in particles w i l l depend on original size, shape and round-ness characteristics, on physical characteristics such as hardness and cleavage, on chemical composition, and on distance and manner of transpor-tation. Effects of abrasion and solution w i l l be expressed in terms of size, roundness, sphericity and surface texture changes and mineral com-position changes. Sorting action taking place in the transporting can be explained in terms of i n i t i a l particle properties. Sorting i s a function of size and shape: the larger and the more spherical grains settle out before those - 25 -which are smaller or have lower sphericity. Sorting also takes place i n terms of mineral composition, specific gravity being the chief control. Progressive sorting may produce a progressive decrease in mean grain size as well as a progressive change in average shapes of particles. Size and shape studies are dealt with in Part V and V H . The general principles on which interpretation of transportation effects are based can be summarized thus: sorting according to size, shape and specific gravity tends to pro-duce variations in the mineral composition of sediments; progressive sorting, as to shape, leads to a concentration of heavy minerals. The most striking effect of sorting noted in the Bute In] et samples i s that due to shape which resulted in large concentrations of biotite. Abrasion versus solution in transportation is a part of sediment transportation studies. Abrasion not only affects size but also roundness of particles. Progressive decrease in mean grain size may in part be due to abrasion, solution, or both. Abrasion also tends to give an ultimate concentration of the more resistant minerals with increasing distance of transport. Glacial abrasion often produces typical "flat iron" shapes. Turbulence is a characteristic of water bodies which exerts a con-siderable effect on carrying capacities of water. In order that a particle shall be carried in suspension by a current, force of gravity must be balanced by a force directed upward such as i s provided by turbulent motion. However the latter w i l l be reduced by stratification in the water body. Such stratification w i l l be produced where there i s a large inflow of fresh water into a basin as in many British Columbia fiords, with con-sequent reduction in carrying capacity due to lack of turbulence. Evidence is presented by Ericson, Ewing & Heezen, (1952) to show that transportation of sediment by turbidity currents is a process of f i r s t importance in - 26 -deep-sea sedimentation and of sufficient effectiveness to explain the origin of the Hudson Submarine Canyon. The distance which particles w i l l be transported in the sea can be measured in terms of their settling velocities, current velocities, tur-bulence and strength of horizontal eddies. KLne particles may be carried considerable distances from coasts by horizontal diffusion alone. Revelle and Shepard (1939 pp. 245-281) used a settling velocity of 15 meters per day as a figure for thoroughly coagulated suspensions and showed how fine particles may be carried away from shore by large scale horizontal eddies. Transportation along the ocean bottom can be described as mass move-ments, mud flows and slides on submarine slopes, and also as sliding or saltation caused by the tractive force of bottom currents together with the effect of turbulence (which raises fine material into suspension making i t available for lateral distribution by diffusion or currents). Such marine sediments as those of Bute Inlet have gone through two main phases of transportation. They have been brought to the sea, by streams and rivers and by shoreline erosion, and they have been transported within the sea. Most material of sand size i s deposited very close to the shore and numerous studies have been made of sediment distribution on beaches and shorelines, many of which are published in the Journal of Sedi-mentary Petrology. Although very few drainage basins studies have been made in Canada, there are several sources of information on quantities of sedi-ments carried in a l l the streams of a drainage area. Brown (1945) gives a compilation and evaluation of a l l known data that might be usable in estimating quantities of sediments carried by streams in the Great Basin interior drainage system, Colorado, Rio Grande and Pecos water sheds. Such data as is contained in this American study would be required for a complete i - 27 -sedimentary study, including determination of rates of sedimentation, in the Bute Inlet area. The second phase of sediment transportation - in the sea - receives considerable attention in studies of the origin of submarine canyons, in which attempts are made to evaluate the relative importance of submarine erosion and river erosion in the formation of submarine canyons (see Shepherd, 1951). In summary, an evaluation of transportation effects in recent marine sediment studies centers about changes in shape, size and composition of individual particles and physical influence of the transporting agencies , upon the distribution of sediments. What i s the relative importance of mechanical breakdown to chemical decomposition during transport? What is, the relative importance of fracturing which gives rise to angular fragments, to abrasion which generally tends to increase roundness? Answers to these questions are important as the size and shape of individual particles not. only indicate the character of transporting agencies and sources of materials but also determine many of the properties of sediments such as water content and cohesion, porosity and permeability. Compositional changes w i l l be most apparent in the softer and more soluble minerals. In the sea, mechanical breakdown i s most likely to occur in materia! moved over the sea bottom by rolling or saltation, whereas chemical action w i l l , be a function of time of exposure rather than character of transporting media. Menard (1950) describes the quantitative relation between grain size, bottom conditions and mean current velocity in shallow water and ex-presses competent velocity in terms of mean current velocity as modified by turbulence, thickness of the boundary layer, depth, slope, and the density, shape and sorting of the bed materia!. An estimation of the importance of progressive change in the character of the material trans-ported necessitates studies of the source rocks, the changes in competency - 28 -of the transporting agency, changes in the sedimentary particles themselves, and the topography and lithology of the river beds and sea bottoms. Rate of Sedimentation Closely connected with transportation phases of sedimentation i s the measurement of rate of sedimentation. Values for rates of sedimentation are of importance in gaining an understanding of past geologic environments, and in carrying out scientific studies of such problems as isostatic balance and tectonic movements. Various methods have been used in arriving at figures for rates of sedimentation. Some of these involve quantitative estimations of cosmic nickel - iron, silicate spherules and coccoliths. Others c a l l for the tying in of data on the position of a volcanic ash layer to the time factor in volcanic eruptions. A method commonly used involves assembling data on erosion in a drainage area and ascertaining the area of the basin receiving the sediments. Studies of varved clays, analysis of pollen grains, quantita-tive catches of foraminifera in ocean waters and identification of species of foraminifera in long cores are the basic procedures in several other methods. It is on the basis of environment, indicated by the vertical distribution of foraminifera, that the Pleistocene age of parts of some of the submarine cores collected from stations in the Atlantic and Pacific Oceans has been indicated. Possibly the most accurate method i s the measurement of radioactivity. The half l i f e of radium Is 1700 years; therefore an analysis of a curve showing decrease in radioactivity with depth w i l l be a means of determining the time factor (Piggot and Urry, 1942). This method, however, is not satisfactory where sedimentation i s proceeding rapidly or at irregular rates because the radioactive elements are so strongly diluted by materials of normal activity that the decrease - 29 -with age becomes imperceptable. Certain corrections must be applied in rate estimations. For core samples, a l l deduced values should be increased by 25 to 65$ because the true length of the sample is shortened during coring. The Kullenberg sampler provides a means of avoiding errors due to shortening. Recent sediments may have 50-80$ water whereas in fossil rocks pore space is generally 10-20$. Therefore before sedimentation data on recent sediments can be utilized in time estimations, values gained from observation of recent sediments must be divided by a factor of 2 to 3. On a basis of present knowledge, a rate of 1 cm. in 500 years i s , considered by many to be a close estimation for deep-sea sediment accumu-lation. L i t t l e data is available on British Columbia coastal rates of sedimentation. Rates of 20 feet per year at the mouth of the Fraser River were observed by Johnson (1921). Other factors being equal mechanical sediments accumulate most rapidly adjacent to coasts where deep water i s close to the shore, because such bottoms receive, over a limited area, the sediments which on bottoms of gentler profile are spread over a wide area. It would therefore be expected that sedimentation rates in fiords would be high. , In estimating the rate of sedimentation in Bute Inlet, the following procedure might be used. Figure 2 shows a map of Bute Inlet with the surrounding water shed. From this map, i t was estimated in this investi-gation that the drainage area i s 3,380 square miles and that, of this, about 560 square miles, or one-sixth, is occupied by snowfields and glaciers. The surface area of Bute Inlet i s 108 square miles. To make an estimation of sedimentation rate, i t would be necessary to have figures on stream volumes and on sediment concentration of the main streams entering the fiord. A bed load measurement structure which operates continuously and permits the - 3 0 -entire sediment load of a stream to be measured with a suspended load sampler has been used with considerable success (Albertson, 1 9 5 1 ) . Such an apparatus would afford a means of measuring sediment concentration, and stream volumes could be computed i n the usual manner or else estimated from precipitation figures plus snowfield and glacier meltw Total volume of sediments delivered to the fiord could then be computed, either from sediment concentration and measured stream volume data, or.from sediment concentration and estimated volumes as determined by precipitation and the melting of glaciers and snow i n the area. Knowing the area of the fiord, a figure for rate of sedimentation could then be calculated. Such a figure to be of any precise value for any drainage area and basin would have to be based on observations made at a l l seasons over a number of years. As no data of this nature are available for the Bute Inlet area, Table I of "Applied Sedi-mentation" ( 1 9 5 0 , p 382), which gives average annual sediment production for various drainage areas i n the United States, was consulted and a value of 2 2 0 tons per square mile - as indicated for the Mokelumne and Herced Rivers - was selected. These rivers have geologic and geographic settings somewhat similar to that of the Homathko River. This value of average armnwl sediment production was used along with the data on areas as scaled from Figure 2 and a value of 0 . 0 3 9 inches per year was obtained. This would give a total of 39 inches of sediment per 1 0 0 0 years as opposed to the accepted figure of somewhat less than one inch for deep-sea sediments for the same period. This figure i s presented as a conservative suggestion for the average rate of sedimentation for the Inlet as a whole, i It would seem that unless an area i s accessible so that sedimen-1 tation, precipitation and stream flow data can be recorded over a period of years, sedimentation rates can best be estimated by radioactive studies of - 31 -sediments. University of Washington Publication .'in Oceanography No. L43 gives results on several hundred radioactive examinations of bottom samples in the Pacific Coast area from Puget Sound to the Bering Sea. The data gathered show a definite pattern of radium concentration, with high radium content being recorded in the vicinity of al l glacier fed inlets. It can be concluded that sedimentation rates for the Pacific Coast Region are best studied by a radioactive method, supplemented where feasible by detailed measurements of sediment production and deposition in favorable localities. For the latter method, stream, flow measurements for many British Columbia; streams are available in Water Resources Papers of the Department of Resources and Development j but the only data on sediment loads of B.C. streams is to be found in 1951 and 1952 publications of the Water Rights Branch, B.C. Department of Lands and Forests, which deal with the Fraser River Basin only, and in the 194S report of the Department of Resources and Development on the Kootenay River. Types of Recent Marine Deposits The environments of source, transportation and deposition give rise to various types of sediments, which can be described in terms of color, texture and composition. Kuenen (1950, p. 336) classifies recent marine sediments as shelf and deep-sea, subdividing the latter under the headings of hemipelagic-terrigenous and pelagic. There is also provision in the classification for mixed marine and for terrestrial sediments such as littoral, deltaic, estuarine and lagoon. Sediments of Bute Inlet embrace several of these categories: littoral deltaic, estuarine and shelf. Their general classification, however, is marine, and as marine deposits they take on characteristics which distinguish them from aeolian, fluviatile or lacustrine types. Herein lies the value of many regional studies of recent - 32 -and near recent sediments of a l l types: a means of expressing as precisely as possible by appropriate laboratory methods the criteria of color, grain shape and composition, organic content, and enclosed plant and animal remains, and thereby defining the principle characteristics of each of the several land and sea sedimentary types. Such studies provide a means of relating geologic environmental factors to physical, chemical, mineralo-gical and biological properties of sediments. This i s a key to an under-standing of the origin and nature of ancient sediments and therefore of service to the petroleum industry; i t is also a basis for making appraisals of sediments for engineering uses and of providing fundamental data to the ceramist and pedologist. - 33 -PART III SOME GENERAL PHYSICAL AND CHEMICAL CHARACTERISTICS Comment Laboratory examination of unconsolidated sediments w i l l include some investigation of mass properties. Mention i s made here of the nature and significance of a few of these properties which are measured during the course of laboratory investigations. By relating the laboratory examination of unconsolidated sediments not only to their environments but also to various ultimate uses to which the information obtained i s applied, better opportunity i s afforded of selecting methods and techniques which provide the maximum amount of data. This applies i n particular to mass properties. Regardless of the type of laboratory procedure, however, the data gathered w i l l be of l i t t l e value i f the samples examined are: not represen-tative of the whole. A plan of sampling i s essential. For recent marine sediments, this might take the form of sampling i n relation to certain shore line and drainage features and also to bottom topography. Once a pattern of sampling has been set, i t should be s t r i c t l y adhered to, regardless of the d i f f i c u l t i e s of actual sampling; for i f samples are only collected where , sample recovery happens to be easy, laboratory data w i l l have l i t t l e significance. Some genera! properties of sediments might be i l l u s t r a t e d by re-ferring to laboratory work of particular value to s o i l mechanics projects. Here, specific gravity, grain size distribution, p l a s t i c i t y , permeability and compaction are important properties and as they are products of source, transportation and deposition conditions, they can be considered as primary properties. The worker in s o i l mechanics w i l l also measure such properties as the natural water content to void ratio, unconfined compressive strengths -34-and consolidation characteristics. These are intermediate properties as they are dependent on both the basic sedimentary material and the loading history. Some secondary properties would also be measured such as precon-solidation stress and relative water content (liquidity index). These are secondary properties as they are a result of post-depositional stress history. Certain procedures in soil mechanics studies are conventionally used in measuring these properties (Taylor, 1948). Although these various tests are designed for the purpose of determining mechanical properties of unconsolidated earth materials, the science of soil mechanics bridges the gap between quantitative studies in engineering and qualitative studies in geology, and therefore any engineering geologic work w i l l extend over into the field of soil mechanics i n , for example, matters of determining con-ditions of instability in landslides and of accounting for active pressures which produce shearing and failure in soil masses. Soil mechanics data can also be used to advantage in fundamental geologic studies, as illustrated by i t s application in correlation and interpretation of Lake Agassiz sediments (Rominger and Rutledge, 1952). A soil mechanics project i s concerned with the soil properties which affect mechanical behavior, the measuring of these properties, stress dis-tribution within a soil mass and the action of soils under stress., As defined by Terzaghi (1943, p. l)> soil mechanics i s the application of the law of mechanics and hydraulics to engineering problems dealing with sedi-ment and other unconsolidated accumulations of solid particles produced by the mechanical and chemical disintegration of rocks, regardless whether or not they contain an admixture of organic constituents. Geologic studies can furnish the worker in soil mechanics with ex-planations of the type and variability in soils. Details on fissuring, - 35 -stratification and textural changes are important in the investigation of soil strengths and stability. The geologist can also reconstruct the history of a clay deposit and by laboratory examination describe the mineralogical components. Such data provides a means of estimating the type, duration and amount of preconsolidation load, which in turn i s of value in interpreting consolidation, settlement and shearing strength data, and of predicting mechanical behavior of clays on the basis of the clay-mineral type. With such applications of geologic data in mind, attention can be given during the laboratory phase of geologic investigation to as many funda-mental and near-fundamental properties as the scope of the project w i l l permit. Color, texture and structure, porosity and permeability, plasticity, shrinkage, compaction, pH & Eh, specific gravity, moisture content, calcium carbonate and organic content,and chemical analyses for such elements as iron and si l i c a are a l l of value regardless of the nature of the sediment being investigated and of the immediate use planned for the information obtained. Color Color of sediments depends on the colors of the large grains, sizes of constituent particles, state of the oxidation or reduction of the iron present and the amount of decomposable organic matter. Color must be des-cribed in the wet and dry state and, for marine sediments, should be ob-served shortly after the sample i s collected as the oxidation-reduction potential may be modified by bacterial activity. When the potential i s oxidizing for iron, reddish or brown oxides are formed thus signifying an environment of free oxygen. An abundant supply of organic material may be the cause of a deficiency in oxygen with resultant reducing conditions. - 36 -Black iron sulphides may form i f hydrogen sulphide is;' produced and greenish or bluish coloring may represent intermediate stages in the oxidation or reduction of iron. Production of hydrogen sulphide is accounted for by the fact that when anaerolic conditions develop, bacteria utilize sulphates as a source of oxygen setting free water and forming the black sulphide of iron. White and light-colored sediments are relatively coarse-grained and are composed largely of quartz or limestone; additions of ferromagnesians imparts a grey color; and the introduction of organic matter in stagnant conditions w i l l give rise to dark colors. Yellow, red and blue colors may also develop with changes in the environment of deposition. In general, color may be explained in terms of the following conditions: black and dark grey are due to anaerobic decay of plant and animal material in marshes, wet plains, stagnant lakes and seas; light grey implies a much wider range of conditions, such as cool rather moist climates on land or a small percentage of residual organic matter in muds of river deltas and oceanic slopes; green i s chiefly the color of pyroclastic deposits and of glauconite muds and sands laid down in slightly reducing marine conditions; red generally implies alternation of rainy and hot dry seasons in the terrestrial source areas with deposition on river plains, in lakes or sea margins, although this color may also develop during the slow oxidation of residual material in the abyssal regions of the ocean. The blacks ,and dark greys are due to organic matter or a preponderance of ferromagnesians; iron compounds are responsible for the reds, browns and yellows; s i l i c a and lime account for the whites and light greys; gypsum, aluminum hydroxides, kaolinite and mica a l l accentuate color variations. During the course of this project the Munsell color chart was used where color definition was required. The Munsell notation i s a' specification - 37 -of color in terms of its three variables, designated as hue, value (brilliance) and chroma (saturation or purity). In the Munsell system, the entire range of hue is divided into 10 equal parts designated by the letters R(red), YR(yellow-red),, Y(yellow), GY(green-yellow), G(green), BG(blue-green), B(blue), PB(purple-blue), P(purple), and RP(red-purple). Each of these is further subdivided by prefixing numbers 1 to 10 with number increasing from red towards yellow-red towards yellow, etc. Thus 5YR is the middle of the yellow-red hue, half way between median red (5R) and median yellow (51) and midway between 10R (which is the same as zero YR) and 10YR (which is the same as zero Y), and also between 2.5YR and 7.5YR. Value Is designated by numbers from 0 for absolute black to 10 for absolute white. Chroma is designated by numbers beginning with 0 for absolute grey and increasing at equal intervals to a maximum of about 20 (Munsell, 1936). Table I l i s t s color descriptions for a few core samples of Bute Inlet samples in the dry state. In general, the Bute sediments in the wet state were found to vary from dark grey to olive-greenish grey for materials of low organic content. Of the cores and bottom samples , examined, Sample number 9 was of particular interest as i t had a thin surface coating of jet black color covering parts of the core. This sample was found to be relatively high in organic matter. Samples in the dry state show l i t t l e distinctiveness of color. Texture In unconsolidated sediments, textures:may be described in terms of grain size and shape, and grain relationship, and there is therefore a close connection between texture, porosity, permeability and degree of compaction. Textural determinations may be only partially representative - 38 -TABLE I COLOR DESCRIPTIONS OF DRIED BUTE INLET SEDIMENTS - MUNSELL NOTATION . Sample No. Munsell Notation Color-Dry 2 51 7/3 pale yellow 1 51 7/2 l i g h t grey-11C 51 7/1 l i g h t grey 8 51 7/1 lig h t grey 9 51 8/2 white 20 51 8/2 white 17 51 8/2 white 23 51 7/1 l i g h t grey 22 51 1/1 l i g h t grey of the deposit sampled due to a certain amount of compaction during coring. An approximate appraisal of texture may he made by visual inspection. Other methods involve mounting and examining i n thin section, and carrying out mechanical analyses, as described i n Part IV. Texture i s mentioned at this point, as i t i s an important mass property and i s closely related to other mass properties of sediments. The grain size classification used i n this study i s that of the Wentworth System, except that the s i l t - c l a y boundary i s taken at 2 microns instead of 5, viz . very coarse sand, 2 to 1 mm; coarse sand, 1 to .5 mm;, medium sand, .5 to .25 mm; fine sand, .25 to .125 mm; very fine sand, .125 to .062 mm; s i l t , .062 to .002 mm; and clay less than .002 mm. Texture of Bute Inlet sediments i s illu s t r a t e d i n Plate IIB which i s a bakelite thin section made by a method described i n Part V. This method affords a means of studying textural characteristics of unconsolidated - 39 -sediments and of thus getting a visual representation of grain sizes and shapes and of relative percentages of sand and silt-clay. Structure Attention is directed in particular to bedding as revealed by textural or color differences. Attitude and direction of bedding surfaces, evidences of cross laminations and of rhythmic or irregular sequences are important data to be gathered. According to Kuenen (1950), practically no information has been collected concerning stratification of shelf deposits due to lack of attention on the part of oceanographic expeditions to this matter and also to difficulties in coring in the coarser materials. Li t t l e is recorded of yearly rhythmic layers equivalent to varves in glacial fresh water deposits. Fraser (1929, pp. 4-9-60) attributes scarcity of varves to the floculation of clay in sea water, which causes i t to sink as rapidly as fine sand. Inclinations of shallow water strata are generally not .large. However along continental margins and about islands, strata may not be continuous nor show small angles of inclination. Where the surface of de-position i s sufficiently steep, slumping may take place and cross lamination may be common. Consequently inclination of bedding planes gives some idea of bottom topography and of extent of slumping. Bedding changes as revealed by textural differences may indicate changes in conditions of deposition, particularly those related to current strengths and directions. In Bute Inlet cores, an interesting structural feature is the occurrence of laminae, at irregular intervals, in some of the cores of relatively coarse sediments. These laminae, up to one cm. in thickness, consist of medium to fine sand, and are manifested by sharp lines of parting between sand and s i l t s , above and below the coarse layers. They - AO -were found to be particularly noticeable in core samples 22 and 23, possibly indicating the presence of rapidly changing currents and conditions of deposition in these areas. The planes of the bedding are very nearly hori-zontal in a l l instances. The bakelite thin section method i s suggested as a means of studying mineralogical and textural changes related to laminae. Structure in unconsolidated sediments can also be considered as the pattern formed by the aggregation of particles or mineralogical complexes into secondary or structural units. Movement of water through unconsolidated sediments is controlled to a degree by structural characteristics; therefore structure should be described whenever unconsolidated materials are being studied as engineering materials or as agricultural lands. In structureless sediments with pores of capillary size, the movement of water is controlled primarily by laws governing capillary movement. In materials with .well-defined structure, percolation of moisture is the paramount feature. In classifying structure as i t relates to aggregates of particles or structural •units, the two determinants are the size of the aggregate and i t s shape. Size ranges from very fine or thin (1 mm.) to very coarse or thick (about 10 mm.). Shape may be described as platy, with one dimension, the vertical, considerably less than the other two and the faces nearly horizontalj prismatic or columnar, with the two horizontal dimensions considerably less than the vertical and with vertical faces well defined; blocky, a 6-faced structure; and a final form, spheroidal or granular. These terms are geometric descriptions of the aggregates making up a given structure. Aggregation may be a result of flocculation and cementation. Cementation about may be brought/through the presence of colloidal clay, organic matter or iron and aluminum colloids. Climatic conditions are important, as drying concentrates electrolytes and this may favor flocculation and cementing of - 4 1 -colloids; wetting may break up large aggregates. Thus there are many ways of describing structure and the methods used w i l l depend on the type and the environment of sediments being studied. Specific Gravity Specific gravity can be described in two ways:; by measuring real specific gravity, that of the individual grains; or apparent specific gravity, that of an aggregated mass of sediment. For real specific gravity determinations, several methods are in use. The Jolly balance method (Dana, 1932, p 219) or for more exact work the Roller-Smith Precision Balance, with a capacity of 25 milligrams, are very rapid ways of making density measurements of small particles. A flotation method (Landes, 1930, p 159) could be used for sand-size material. The Chatelier flask method, in which a flask or specific gravity bottle with a graduated neck is f i l l e d with distilled water to a given volume mark, the flask weighed, the sample placed in the water, the new volume and weight noted and the specific gravity calculated from weight and volume differences, i s a convenient method of determining real specific gravity. Finally, the pyconometer method, which i s similar in principle to the Chatelier flask method, can be used where a high degree of accuracy is required. In this procedure, accuracy in measurement i s assured by placing the pyconometer, containing water and sample, in a vacuum desiccator and evacuating t i l l a l l inter-s t i t i a l air i s removed. To determine apparent specific gravity of a mass of sediments, a sample i s placed in a bottle and after voids have been eliminated the level of the surface i s accurately marked, the bottle and sample weighed, the weight of the bottle empty and f i l l e d with water to the sample mark noted and specific gravity computed from the sample and water weights. At best - 42 -this gives very approximate results, but i f a fixed procedure i s used each time, may be adapted for comparative work. A volumetric method may also be used:; the sample i s coated with parafin or colloidion, i t s volume as-certained by immersion in a graduated tube, and the volume i s then divided into the weight of the sample before coating. The apparent specific gravity w i l l be governed by the structure of the sample and by the percentage of low density materials, such as clays and organic matter. Clays and s i l t s have a general range of 0.9 to 1.60 in apparent specific gravity, but in the more sandy materials this measure-ment w i l l be in the range of 1.2 to 1.8. Very compact sediments, regardless of texture, may go as high as 2.0. Thus apparent specific gravity must be considered in terms of texture, structure, moisture, organic matter content and degree of compaction. Heal specific gravity i s a measure of the density of individual mineral particle and is therefore unaffected by structure and compaction. As quartz and feldspars are usually dominant, sediments of relatively pure mineral content w i l l have a real specific gravity of 2.6 to 2.7. However large amounts of organic matter or a large percentage of heavy minerals w i l l alter these figures considerably. Porosity and permeability are closely connected with apparent and real specific gravity. Porosity Porosity is expressed in terms of the percentage of the total volume of a sample which i s occupied by pore space. It is usually a maximum in free unconsolidated sands although i t may be higher in some clays j i t i s a minimum in quartzite. In addition to the amount of cement material, the characteristics of primary particles which affect or control porosity are grain size, shape, roundness or angularity, surface texture, - 43 -orientation of particles and mineralogical composition. The mass property of porosity, l i k e a l l other mass properties, i s controlled by individual particle characteristics as well as by other phenomena such as sorting, packing, weight of overburden with attendant strain, and contact with fluids. The examination of unconsolidated sediments affords a means of comparing such mass properties as sorting with properties of component particles and the relationship so established can then be compared with similar studies of consolidated sediments. The smaller the grain size, the greater i s the porosity but highest porosity i s commonly found where grains are of uniform size. Usually angularity of grains has a tendency to increase porosity. In ;general, nature and variety of materials deposited, their size sorting and packing are the main c r i t e r i a to be examined in porosity studies. Glacial .deposits are characterized by low porosity, river and stream deposits somewhat higher and subaerial deposits by even higher porosity. Beach sands commonly range from 38 to 45$ i n porosity; and surface clays 45 to 50$, although freshly deposited clays and s i l t s may exceed 85$ whereas i n the dried and compacted state they may only have a porosity of 40 to 50$. Clays, though possessing a low permeability, have a large number of small pores which con-tribute to a high water-holding capacity and porosity. Sands have a small number of larger pores, which are responsible for rapid drainage resultant upon high permeability and therefore have low moisture holding capacity. Measurement of porosity involves determination of pore volume and bulk volume. Numerous methods are used for porosity ratings of consolidated sediments (Leroy, 1951, p 692; Pyles, 1950; Pettijohn, 1938, p 506; Twenhofel and Tyler 1941, p 145). In the examination of cores of consoli-dated materials, the most convenient and most widely used tool for measuring porosity i s the Kobe porosimeter. Several methods may be tried - U -i n working with unconsolidated sediments. One procedure consists of selecting a block of aggregated material, saturating i t i n water, coating i t with either paraffin or collodion, taking weight and volume, melting away the coating, expelling the water by heating i n an oven and weighing again thus getting the water loss which i s a measure of the pore space. For a rough f i e l d determination, the dried sample i s placed i n a graduated beaker, the volume read and then a known volume of water added sufficient to f i l l the total pore space, the amount of water added being a measure of porosity. A somewhat similar method i s described by Fraser (1935, .p 936). Another procedure, found quite suitable with most samples, i s to use mercury as an immersing f l u i d into which the sample, without any coating, i s placed and the overflow i s caught and measured. The method used i n measuring porosities of Bute Inlet cores, was as follows. A sample of core about three inches long was selected, oven dried and weighed. It was then coated with paraffin and immersed i n a large graduate to determine volume by displacement. Weight and volume figures then were used to compute apparent specific gravity. Real specific gravity was determined by the Chatelier flask method. Porosity was calculated by dividing apparent specific gravity by real specific gravity and multiplying by 100 to give the percentage of total volume occupied by mineral grains,, and then deducting this amount from 100 for the porosity figure. Table II shows the results of several porosity determinations together with.illus-tration of the method used i n computing real specific gravity. Median diameter figures, as determined by mechanical analyses, have been included i n the table as indicators of the textures of the various samples, and as such they bear an inverse relationship to porosity. A serious objection to this procedure of porosity determination - 45 -TABLE II SPECIFIC GRAVITY AND POROSITY BUTE INLET SEDIMENTS Specific Gravity - Le Chatelier Flask Method Weight of flask 25.34 gms. Volume of flask 50.00cc. Weight of flask plus sample 35.46 gms. Weight of flask plus sample and water 81.67 gms. Weight of water 46.21 gms. Water displaced (50-46.21) 3.79 c c . Specific gravity, sample #17 — 10.12 2.67 3.79 Porosity Sample No. Apparent S.G. Real S.G. Porosity Median Dia. 23 1.80 2.68 36.9 .022 mm. 17 1.68 2.67 37.1 .014 mm. 9 1.63 2.65 38.5 .011 mm. 20 1.62 2.65 38.8 .010 mm. 11B 1.17 2.63 55.6 .006 mm. 28 1.14 2.62 56.5 .002 mm. l i e s i n the fact that after oven-drying, data obtained may not be truly representative of the natural pore size and distribution i n the sediments from which the sample came. This w i l l be particularly true i f there i s a f a i r l y large clay-mineral content. In such an event an estimation of total porosity may be made by use of the Tension Table. This apparatus i s employed i n soils work for working out pore size distributions up to the pore size from which the air-water interface i s withdrawn at a tension of 100 cm. of water. A s o i l core i n a tube i s saturated with water and placed - 46 -on the table. Readings are taken at tensions up to 1G0 cm. and water-weight losses recorded at each 10 cm. of rise i n tension. From the data so obtained, total porosity and non-capillary porosity can be calculated. This apparatus was experimented with and i t i s suggested that use be made of i t i n porosity examinations of any types of unconsolidated sediments. It has the limitation, common to a l l porosity methods for unconsolidated sedi-ments, that the sampling process may cause compaction and thereby distort the pore space arrangement to a certain degree. It has the distinct advantage of permitting testing without f i r s t drying the sample. Permeability Iiike porosity, permeability i s also controlled by texture and packing. .Permeability depends upon the dimension of pores and also upon the extent to which they are connected. Permeability i s a character of the rock, not a character of the f l u i d used i n determining permeability; there-fore for any one rock - and direction within the rock - the permeability i s the same irrespective of the f l u i d used. Mathematically, the factors des-cribed as affecting rate of movement of a f l u i d through a permeable solid are hydraulic gradient, viscosity (as affected by temperature) of permeability. This coefficient i s an expression of uniformity and range of grain size, shape of grains, nature and amount of packing, surface conditions of the grains, s t r a t i f i c a t i o n and cementation. Variations i n grain size and stratification have the most important affects on permeability. Grain shape i s said to be less important. I f pores are small enough so that attraction of water particles i s sufficiently.great to hold fluids as films around mineral particles, then permeability approaches zero. Permeability may therefore be described i n terms of the f a c i l i t y with - 47 -which fluids may pass through rock materials, unconsolidated or consoli-dated. Permeability i s not necessarily a function of porosity as clays may be very porous but have low permeability. Changes i n permeability through-out a deposit are a reflection of v a r i a b i l i t y during a l l stages of the history of the deposit from erosion at the source to post depositional changes. Like porosity, too, permeability i s a property requiring considerable attention i n o i l and gas f i e l d studies and i n water supply problems, as the accumulation and recovery of o i l , gas and water are dependent upon their a b i l i t y to move through strata and to collect i n suitable reservoir rocks. Prom the standpoint of ground water supply, a coarse s i l t (about .02 mm. i n particle size) i s practically impermeable, and any large proportion of this material i n sand w i l l lovrer the permeability accordingly. Many techniques are used i n measuring permeability of consolidated materials (Leroy, 1951, p 699) but a l l have one objective: to measure the, quantity of f l u i d that passes through a selected specimen of measured cross-sectional area, and thickness i n a given time. D'arcy's law, based on experimentation, states that the velocity of a homogeneous f l u i d through a porous medium i s directly proportional to the hydraulic gradient and inversely proportional to the viscosity of the f l u i d . The permeability i s measured i n terms of the unit w d a r c y % which i s the rate of flow, i n mm. per second, of a f l u i d of one centipoise viscosity through a cross section of one square cm., under a pressure gradient of one atmosphere. In the formula, the coefficient of permeability i s equated to the product ,of water quantity, length of sample and correction for temperature, divided by the .product of time, cross sectional area of sample and hydrostatic head. A more d i f f i c u l t problem i s presented i n assessing the permeability - 4-8 -characteristics of unconsolidated materials, as sampling is bound to dis-rupt, to a degree, the packing and therefore the pore sizes and distri-bution. Tolman (1937, p. 208) describes an apparatus capable of measuring permeability within the degree of sampling accuracy. This method was used in running several tests on Bute Inlet cores. The-, apparatus is simply a glass tube, two inches in diameter and six inches long, with a screen or heavy f i l t e r paper clamped on one end. After the sample is placed in the tube, a one-hole rubber stopper with a glass vent and rubber hose connection, is placed in the other end. The amount of water, as supplied from a gradu-ated burrette to which the rubber hose is connected, passing through the sample is measured, and the average head can be determined from the burrette readings. The D'Arey formula can then be used to determine permeability. Results of tests run on samples number 22 and 1 gave values of 12 and 9 millidarcys respectively. A somewhat more elaborate apparatus is described by Fraser (1935, p. 948) and by Stearns (1927, p. 144)• For running a large number of samples, such an apparatus would be more suitable as conditions of control during the tests could be better standardized. However, the central problem remains: that of removing a sample from its natural environment without changing permeability characteristics. In petroleum work, a l l matters relating to permeability measurements are standardized and laid down in American Petroleum Institute Code 27 (A.P.I., 1942). Moisture Content The amount of water held by any sedimentary mass can be described in several ways. Hygroscopic water is water held as a film of molecular dimensions, and the amount in sediments is therefore dependent on the total - 49 -surface area of grains, which in turn is a function of grain size and of chemical nature of the sediment. The hygroscopic coefficient is the per-centage of such water held in equilibrium in a saturated atmosphere. The amount of hygroscopic water held by clays varies with the clay-mineral type. Clay minerals may have a large amount of water partly bound up as water of crystallization and partly held by surface and interlattice absorption. In the case of clays with expanding crystal lattices, absorption may take place between the sheets as well as on the exterior of the particles. Thus mont-morillonite will hold more water than beidellitej and halloysite and kaolinite, because of fixed lattices, will hold the least of the clay minerals. Chemical composition of clay minerals also influences water con-tent: within the same mineral class, i t increases with the amount of silica. Water content also varies with the amount and nature of the absorbed cation of clay minerals. The larger the total exchange capacity the greater is the hydration of the clay, with the exception of K. ions which cause the lowest absorption and swelling, possibly because of their weak ability to orient water molecules. Hygroscopicity of clays may be measured by placing dried samples of known weight in a desiccator containing a wet sponge. After the samples have remained in this wet atmosphere for a few hours and have been; checked at constant weight, the hygroscopic coefficient may be determined as a percentage of water absorbed. (Wallace and Maynard, 1924). Moisture equivalent is another manner of describing water content. This parameter is an approximate dividing point between capillary and non-capillary moisture and is a function of particle size. Each sediment textural type - sand, s i l t and clay - has its own characteristic moisture equivalent. Moisture equivalent also increases with organic matter con-tent. Moisture equivalent determinations are made under certain arbitrary experimental conditions, but generally the figure obtained is the percent by weight of moisture that is retained in a saturated specimen after i t has been centrifuged at 2440 R.P.M. for 40 minutes. The moisture released is determined by difference, after oven drying (Briggs and McLane, 1910; Steams, 1927, p. 137). A ready method of determining water content is simply by drying a sample overnight in an oven at 105°C, and computing the water loss as a percent of dry weight. Although the method may be reasonably effective for making comparisons within a given sediment, i t has li t t l e value as a general comparative procedure as large errors may be introduced due to varying amounts of water loss during sampling. This method, however, was used on Bute Inlet samples, but i t is suggested that future work should also include some such standard and comparative method as the determination of moisture equivalent. Table III gives results of water determinations for some Bute Inlet samples along with some shrinkage data. As the samples listed are repre-sentative of all those examined, a figure of 40 to 50% total moisture con-tent appears to be characteristic of Bute Inlet recent marine sediments. Glosely related to water content of sediments, particularly where clay minerals are important constituents, are the properties of bonding strength and plasticity. Every clay mineral is characterized by a certain ability to stabilize water, and the rigidity with which the clay mineral particle hold water on its surface is a determining factor in these two property effects. (Grim and Guthbert, 194-5). These clay-water properties are also of value in explaining the difference in texture between sediments dominantly i l l i t e , which generally have a laminated texture, and sediments composed of kaolinite. Furthermore these clay-water properties help to explain large scale structures in unconsolidated sediments . Many physical - 51 -TABLE 111 MOISTURE AND SHRINKAGE DATA - BUTE INLET SEDIMENTS. Sample No. 23 20 17 9 7 Wet weight in grams 37.0 40.7 45.2 39.4 34.4 Dry weight in grams 26.4 27.0 31.4 26.5 22.5 % Moisture 39.9 50.5 43.8 48.8 52.8 Shrinkage in c.c. 1.7 5.8 3.6 4.8 7.6 Shrinkage % 6.8 23,2 14.4 19.2 30.4 Shrinkage Limit 33.6 29.1 32.3 30.7 18.9 % Cl ayrsize fr action 8.0 26.0 18.0 22.0 31.0 characteristics of soil mechanics properties are explained in terms of clay-water phenomenae. In ceramics, the working range of plastic clay bodies is a function of clay-water criteria. Plasticity Plasticity may be defined in the terms of mathematics and physics; i t may be given a practical definition, such as "the property which solid bodies show of absorbing and holding a liquid in their pores and forming a mass that can be pressed in any desired shape, which i t retains when pressure ceases, or on withdrawal of water by evaporation changes into a hard massn; or this property may be explained in terms of mineralogy. The mineralogic approach explains why a sediment has a certain degree of plasticity; other descriptions are more concerned with the effects of this property, as described by arbitrary concepts. - 52 -Water added to dry sediment i s absorbed on the basal plane surfaces of clay minerals and possibly some other minerals. The water molecules have a definite orientation on the surface layers and for several molecules of thickness above the basal plane i n line with the oxygen layers i n the sur-face of the clay mineral units. Thus the i n i t i a l l y absorbed water i s not fl u i d . However as oriented water molecules only grow to a certain thickness, any excess water w i l l not have i t s molecules oriented and w i l l therefore be fl u i d . The r i g i d or oriented water would act as a bond to hold clay units in place; excess water would act as a lubricant between flakes. The plastic condition develops where there i s enough water' to supply a l l the ri g i d water that clay flakes can hold plus additional water which has l i t t l e i f any orientation and therefore acts as a lubricant (Grim, 1950, p. 6). Montmorillonite has a much greater plastic l i m i t (about three times) than kaolinite or i l l i t e because water can penetrate between individual unit layers of i t s l a t t i c e structure, and also because of i t s f a c i l i t y to break down into very small flake-shaped units with consequent tremedous surface areas with particular a b i l i t y to absorb water. The importance of knowing what clay minerals occur at proposed foundation sites i s therefore evident, and there are many other applications to which fundamental clay data can be put. , Plast i c i t y may be measured roughly by ro l l i n g s o i l material between thumb and finger and observing whether or not a wire can be formed, and i f so, the range of moisture content within which pl a s t i c i t y continues. I f no wire i s developed, the material i s non-plastic; i f the wire i s easily deformed, slightly plastic; i f moderate pressure i s required for deformation; of the wire, i t i s plastic; i f much pressure i s required for deformation, i t i s very plastic. - 53 -Plasticity may also be described in terms of the Atterberg limit, plasticity limits: liquid/ plastic limit and plastic index. These terms are explained by Rominger and Rutledge (1952, pp. 160-180) who point to the value of these criteria in geologic correlation work. As measured in the laboratory, they are a means of aiding field recognition of stratigraphic units which are difficult to separate by field methods alone. Specific gravity, grain size and shape, permeability, compaction and strength test data can be combined with plasticity data to increase further the effective-ness of laboratory procedure in the solution of field problems. Casagrande and Fadum (1940) explain how the several plasticity tests, along with other physical tests, can be carried out under standardized conditions. Field applications of such data are also described by White (1949 pp. 507-512) who found that Atterberg limits increase with decreasing particle size. Kay (1950, p. 109) states that geologic observations may be of far reaching consequence in furthering knowledge of mechanical properties of clays and that plasticity is a property as important to study of cohesive soils as are grain size, rounding, and mineral content in the study of sands. Bonding Strength The measurement of bonding strength has wide application in industrial use, and although this property is of itself not a geologic criterion for describing unconsolidated materials, i t is of interest to note what mineralogical properties control this mass property. Of the clay minerals, montmorillonite provides the highest bonding strength, and its presence in a clay raises the strength out of a l l proportion to its presence. Strengths of kaolinite clays are much lower and of i l l i t e clays, lower s t i l l . This difference is ascribed to the fact that montmorillonite either occurs in minute particles,or in large particles that break down - 5A -more easily than other clay minerals. Non-clay mineral content, such as quartz and feldspar, has l i t t l e effect on bonding strength, unless i t is present in excess of 30%. The relation of clay mineralogy to the bonding action of clays has received extensive investigation (Grim and Rowland, 1940, pp. 24-36; Grim and Cuthbert, 1946). Bonding strength can be taken as a measure of cohesion and impact resistance. Puri (1949, p. 327) considers these latter two properties to be fundamental physical characteristics and has set up certain arbitrary standards for measuring them. Strength tests based on bonding action are carried out in industry in accordance with the procedures of the American Pbundrymen's Association (1944-). It i s of interest to relate geologic properties to standards as used by industry. Shrinkage and Swelling Volumetric changes in sediments depend largely on the amount of clay material present and specifically on the clay mineral predominating. Ah explanation of this fact i s obtained by examining the mineralogieal data which recent research has made available on mineral lattice structures. There are two structural units making up the lattice:: aluminum hydroxide or alumina, which consists of two sheets of closely packed 0 and OH atoms, between which Al. atoms are embedded equidistant from 6 O's or OH's;; and a sheet of Si 04 groups, linked to form hexagonal networks of Si4 010. This is the gibbsite structure. The montmorillonite lattice is one gibbsite structure between two Si4 010 sheets, stacked in the direction of the C axis and held together by water between the units. Thus the C axis varies in length with the water content and there is great facility for absorbing a large amount of water. - 55 -In the i l l i t e structure, Si i s replaced ty Al in the Si,4 O^Q sheets. This extra charge prevents absorption of water by hindering expansion of the lattice. The kaolinite lattice consists of one gibbsite sheet and one S i ^ O^o sheet and is therefore non-expanding and not capable of taking up much water. . These mineralogical criteria thus explain changes in the mass properties of shrinkage and swelling and consequently are essential to stress and load appraisals of unconsolidated materials. Table III shows values for shrinkage as measured for several Bute, Inlet cores. This table l i s t s observed values for wet and dry weight, from which the moisture content was calculated, shrinkage amounts as obtained by the difference between wet and dry volumes, values of the shrinkage limit as computed from the percentage of moisture less the percentage of shrinkage to i dry weight, and the amount of the sample which i s less than two microns in size (the clay-size mineral fraction) as obtained from hydrometer curves in Figure 6. This table shows that the moisture content.varies directly with the amount of the clay-size fraction, and that the shrinkage limit values vary inversely with the amount of this fraction. The shrinkage data of this table would seem to indicate an absence of montmori llonite in the clay-size fraction. I Base Exchange, Base exchange i s also an indicator of the nature of clay minerals in sediments. In the process of base exchange, cations in a solution may enter the crystal structure and replace a stoichiometrical equivalent of another ion, which then passes into solution. Thus i t is possible to have H, Ha, K and Ca clays, where these elements are the replaceable cations. Many of the physical properties of clays can be explained in terms of the replaceable cation: sodium clays are sticky, impermeable and readily dispersed; calcium - 56 -clays are relatively granular and porous and are d i f f i c u l t to disperse; and each of the other clays also has certain distinguishing features. Plasticity-i s also a function of the nature of basic ion content. Exchangeable ions also exert an influence on the a b i l i t y of a clay mineral to stabilize water. In general, the influence of exchangeable bases on physical properties i s considered to be due to the fact that as ions have different dissociation a b i l i t i e s , the hydration spheres enclosing the clay particles vary with the identity of the exchangeable base, with consequent affect on physical properties. The most obvious effect produced on clays and clay sediment by base exchange i s reflected i n their permeability. As calcium saturated clays tend to be granular and comparatively porous, and sodium clays relatively impervious due to high dispersion, there w i l l be a distinct difference, between these two clays, i n permeability. Base exchange investigations of marine sediments provide data on environment. One question to be answered i s whether or not any exchange takes place when terrigenous clays are deposited i n a marine environment. If magnesium was found to form the principal replaceable base, followed by sodium, calcium and potassium, i t might be assumed that the clay minerals of marine sediments had attained an equilibrium with sea water, as i t con-tains, i n order of abundance, sodium, magnesium, calcium and potassium. Magnesium has a higher replacing power than sodium and would therefore be a more abundant replaceable base. Furthermore, during rock decay, the nature of the elements released has a specific bearing on the sediment properties. S i l i c a and aluminum furnish the skeleton for the production of clay colloids; iron and magnesium are important for oxidation - reduction pro-cesses and i n color determinations; potassium and sodium are dispersing - 57 -agents for clay, whereas calcium and magnesium have high flocculating powers and insure s o i l stability. Breakdown of acid igneous rocks high i n quartz provides a surplus of monovalent cations, whereas basic igneous rocks are sources of sediments high i n calcium and magnesium. Thus, the nature of the source rock, as well as the environment of deposition, i s an important factor i n sediment properties as related to cation content. An application of base exchange capacity data to f i e l d work i s given by Grim and Allen (1938, p. 1494) who obtained exchange capacity values for a series of samples taken i n vertical sequence i n an underclay. The consistency of values obtained, along with other pertinent data, i n d i -cated that the clay mineral content of the underclay being studied was uniform. Base exchange data i s therefore an aid i n describing clay mineral distribution i n a sediment. Base exchange capacity of montmorillonite i s much higher than that of kaolinite. By virtue of i t s crystal l a t t i c e structure i n which OH ions are a l l attached to aluminum and the sum of the positive charges of si l i c o n and aluminum equals the sum of negative charges of 0 and OH ions, pure kaolinite contains practically none of the common bases, because the com-plete l a t t i c e possesses no unsatisfied e l e c t r i c a l forces by which other ions can be held to the l a t t i c e . In montmorillonite, the l a t t i c e cations carry only one half as many OH ions per aluminum ion as they do i n kaolinite and the distance between adjacent layers of the l a t t i c e i n montmorillonite i s not constant as i n kaolinite but varies with the water content. Montmori-ll o n i t e also does not become unstable by;, substitution of magnesium for aluminum because i n each l a t t i c e layer the magnesium ions would occur be-tween s i l i c o n ions. Consequently, the difference i n crystal-lattice structure between the two minerals accounts i n part for different base b - 5B -exchange power, although no theory f u l l y explaining base exchange has been firmly established (Kelly, i n Recent Marine Sediments, 1939, pp. 462-63). The measurement of exchange capacity and exchangeable bases i s commonly done by the Ammonium Acetate Method. This involves the preparation of a normal ammonium acetate extract and leaching of the sample for at least, four hours. After the acetate leaching, the determination of exchange capacity and of exchangeable hydrogen, calcium, magnesium, potassium and . sodium i s carried out by a t i t r a t i o n procedure using standard al k a l i s . This i s a lengthy procedure, requiring approximately two days to run four samples i n t r i p l i c a t e . Puri (194-9) discusses the theory and procedures of base exchange methods and points out that these methods do not give the same results and consequently care must be taken to specify the exact techniques used i f the results are to have any comparative value. An explanation of procedure i s also given by Marshal (1935, p. 21). It i s important to note regarding base exchange determination of marine sediments that leaching with pure water or treatment with any salt solution, such as those used as dispersing agents, w i l l tend to bring about certain changes i n the exchangeable cations i n clay minerals. Therefore studies of base exchange properties must be made on sediments which have not been washed or treated i n any manner, and should be carried out on samples which have been carefully preserved i n air-tight cylinders during the interval between sampling and testing. The test work should be carried out as soon as possible after sampling i n order to minimize effects of chemical and bacteriological changes which might be taking place i n the sediments. I f a ship employed on oceanographic work were f i t t e d up with a small laboratory, some of these properties of sediments such as color, pH and Eh, water and organic matter content, base exchange characteristics and - 59 -bacteriological counts could be made during the f i e l d season, and the infor-mation so obtained would then be much more representative than i f the examination were made at a later date. pH and Eh pH, hydrogen ion concentration, i s a measure of intensity of acidity, which i n turn i s a manifestation of excess hydrogen ion concentration over hydroxyl concentration. A low pH indicates high acidity and i s caused by the presence of soluble and insoluble acids i n excess of the bases present. Acids, such as hydrochloric, sulphuric and the various insoluble acids of clay particles such as A C 2 S i 2 Oo, are freed during rock weathering. In addition, the decomposition of organic matter also contributes acids. Soils tend to become acid especially i n humid regions as bases are more easily removed by leaching; moreover these areas are usually rich i n vegetation which produces organic acids. In arid regions, the reverse i s true, and soils tend to be neutral to alkaline. In recent marine sediments, pH i s a measure of net acidity, due to the entrapped sea water, the organic acids generated by action of bacteria on organic matter, and the presence of any mineral acids formed from clays or other minerals. An important constituent of this t o t a l acidity i s that generated by microorganisms; therefore i f the pH i s to be representative, i t should be measured shortly after the sample i s taken. pH should be measured at a l l depths i n cores to see i f there i s any change with depth. Generally, i n t e r s t i t i a l waters become more alkaline with depth. There i s also a direct relation- between pH and grain size. Eh values may be determined as well. Heintze (1935, pp. 351-355) claims there i s a close connection between pH and Eh. It i s generally - 60 -believed that Eh (oxidation-reduction potential) values cannot be used for anything other than for diagnosing acutely reducing conditions, and some investigators believe that pH and Eh are so closely related that pH suffices to indicate Eh. The results of Eh determinations are strongly influenced by the methods used and as yet no single method has established i t s e l f . L i t t l e i s known of the development of reducing conditions i n marine sediments and of the oxidation-reduction potentials of these deposits, but the problem i s of importance i n gaining an understanding of the genesis of petroleum. pH and Eh are included i n this description of physical and chemical properties because they are of particular value i n describing marine sediments i n terms of their characteristics as possible source sedi-ments for petroleum. pH can be measured by adding a few drops of triplex indicator to a small sample of sediment i n a spot plate and comparing the colors developed with those of a standard color chart graded in terms of pH values.. This w i l l give the value to within 0.5. A more accurate method i s to use the Beckman pH meter - Industrial Model M - which measures values to the nearest 1/100. To prepare samples for this method, a 1 to 5 s o i l xrater ratio i s used, the s o i l being mixed i n d i s t i l l e d water i n an el e c t r i c drink mixer for five minutes. Results, for Bute Inlet sediments, of pH tests using the pH meter are shown i n Table IV. Eh can also be measured by using a standard pH meter. It i s ex-pressed as an intensity factor and can be measured potentiometrically by using platinum electrodes and a Beckman pH meter unit with a voltage extender. pH and Eh are dynamic elements of the environment. They are a of measure,physical-chemical processes that are generated or modified within a given environment, and as dynamic factors, these electrometric - 61 -TABLE IV pH Values - Bute Inlet Sediments Sample No. 23 22 27 25 18 pH 7.11 7 .00 7.22 7.10 7.26 Sample No. 13A-1 13A-2 12 11A 11B PH 7.18 7 .00 7 .55 7.71 7 .55 Sample No. 10 4 3 2 1 pH 7 .40 7 .36 7.32 7.34 7.92 characteristics are susceptible to constant change. Therefore they should be measured as soon as a sample i s taken, and furthermore samples should be taken several times a year for complete information. pH values recorded i n this report are of l i t t l e significance because tests were made about eight months after sampling, and i n some instances sample tubes had been broken in transit. However, of a l l observations to be made on recent marine sedi-ments, those for pH and Eh are the most easily made, and they could be recorded at the time of sampling with l i t t l e d i f f i c u l t y . Organic Matter The organic content of marine sediments has an importance to the investigator of source beds of petroleum (see Trask, 1934-). Sediments formed i n a marine shallow water environment have a greater abundance of l i f e than those of other parts of the ocean bottom of equal area. It i s here that most mollusks, brachiopods, reef-building corals, foraminifera, bryozoans, echinoderms, arthropods and diatoms, and many vertebrates l i v e . In the course of mechanical analyses of sediments, organic constituents recovered i n each size fraction can be examined and identified, and the f i n a l picture should show the part that each organism takes i n the overall - 62 -sedimentary composition. Individual examination of species w i l l reveal physical conditions with respect to wear, breakage and habits of l i f e , a l l of which contributes to an understanding of the environment. Deep-sea sediments, known as oozes, are largely composed of organic remains and are called diatomaceous ooze or radiolaria^ooze. On continental shelves, generally speaking, the organic content i s only a very small per-centage of the total sediment volume. Sedimentary products composed dominantly of s i l i c a are the radio-larian and diatom oozes and siliceous sponges. The dominant organisms of Bute Inlet samples are foraminifera, sponge spicules and diatoms (See Part V). The spicules are composed of hydrous s i l i c a and organic matter. Diatoms are also abundant, and i t i s to be noted that Bute Inlet waters are of low salinity, the most favorable environment for diatom growth. Much of the soluble organic matter which dissolves i n sea water when plants and animals die or are k i l l e d i s u t i l i z e d by bacteria. Bacteria convert organic detritus into marine humus which i s similar to humus formed on land. Thus there i s an important relation between organic matter and bacteria, as the former i s the source of energy for bacteria i n their role as biochemical agents. The balance struck between organic matter and bacteria i s an important factor i n the development of petroleum source beds. The organic matter from which petroleum forms contains carbon, hydrogen, oxygen, nitrogen, sulphur, phosphorus, etc. That organic matter which i s not used up by bacteria and bottom l i v i n g forms constitutes an amount varying from zero to 18$, and averaging 2.5% i n near-shore sediments. Much organic matter i s of immediate marine origin, but some i s of t e r r e s t r i a l origin, derived from s o i l humus and carried to the sea by rivers. Many factors, therefore, contribute to the form and amount in which i t f i n a l l y - 63 -occurs in sedimentary beds. Organic matter of sediments can be measured as a total content and i t may be further described in terms of such components as carbon, nitrogen, proteins, fatty materials, cellulose and lignin. In this project, a procedure was used to determine the total organic matter content only. Figure 11 shows the results of these tests. This method, which has to a large extent replaced the ignition method, consists essentially of adding potassium dichromate to a one gram sediment sample, then adding concentrated sulphuric acid, allowing solution to stand for 30 minutes, adding water, phosphoric acid and barium dipherylaminesulfonate indicator, and titrating to the end point with ferrous sulphate. The com-putation i s made by multiplying the number of millimeters of potassium dichromate reduced, by a factor 0.69, and dividing this product by the weight of the sample. The Bute Inlet samples were run in triplicate to insure maximum accuracy. Once the samples have been prepared and weighed and the solutions prepared, the actual determination can be done at the rate of about 10 samples per day, in triplicate. Other methods are given by Trask (1934) and by Twenhofel and Tyler (1941, p. 125-127). In the matter of distribution of organic matter in marine sediments, i t has been found by some investigators that the percentage of organic matter increases with decrease in grain size. This is possibly due to the fact that large grains allow water to circulate and introduce a fresh supply of oxygen into the deposit, thus reducing the organic content in the coarser sediments. Organic matter percentage also decreases with rising percentage of lime and with decrease in depth. Another control in the relative amount •of organic matter present is the rate of sedimentation. Two basins having similar supplies of organic constituents w i l l not have equal percentages i f - 64 -one basin is receiving inorganic debris at a higher rate. Green and black muds, rich in organic matter, are products of the euxinic environment, where oxygen deficiency is the chief characteristic. Some Norwegian fiords have 10 to 20% organic matter. In Bute Inlet, the general circulation of waters is much better than in the Norwegian fiords, and there are not the large stagnant basins characteristic of the Norway coast. This is evidenced by the abundance of diatoms, which are generally characteristic of areas where upwelling or mixing is operative. Furthermore, of the organic matter analysis made, none exceeded 4*5$, the average being closer to 1%. Sample number 9 may have come from a stagnant area, however, as the core was covered with a thin dark black coating and had a hydrogen sulphide smell. The majority of cores and bottom samples appeared to have come from areas of good circulation. Conclusion regarding organic matter content in relation to particle size and carbonate percentage must be based on many analysis. The few analyses made show a relation of highest organic content to samples of smallest median diameter. No comparison can be made between carbonate and organic matter percentages, however, due to the fact that, except for one or two samples, a l l carbonate percentages are very low, well under 0.5%. Of chief interest in the investigation of organic matter component is the pertinence of the data to researches in the origin of petroleum. A summary of progress made over the years and of the present state of knowledge has been given recently by the Institute of Petroleum Review (1952) and by Ion (1952, pp. 613-615). These surveys illustrate well the importance of recent marine sedimentary studies to a furtherance of present knowledge of the origin and mode of accumulation of petroleum. - 65 -Calcium Carbonate The calcium carbonate content of sediments is influenced by many factors, such as temperature, depth of water, salinity, hydrogen ion con-centration, degree of saturation of calcium carbonate in the water, activity of living organisms and the proportion of terrigenous debris in the sedi-ments (Trask, 1936, p. 1). Most of the dissolved carbonate of sea water occurs in the upper layers, and i f an increase in salinity from 34 to 35 parts per million occurs i t raises the degree of saturation of the water with respect of calcium carbonate 8.4$. An increase in temperature from 20 to 21°C raises the degree of saturation 4.6$. Sediments in regions where the salinity of surface waters is less than 34 parts per 1000 in general contain less than 5$ calcium carbonate. In the ocean depths, calcium car-bonate may be redissolved. The majority of the Bute Inlet samples examined were found to contain less than j$ calcium carbonate (see Part V). In general, conditions for precipitation of calcium carbonate are most likely to occur in waters having high temperature and high salinity and where activity of plants has reduced the carbon dioxide content of the sea water. It would therefore be expected that the waters of British Columbia fiords would precipitate very l i t t l e calcium earbonate. The other form of carbonate occurs as skeletal shells or structures of plants and animals. In Bute Inlet sediments these are predominantly silicous, the exception being small amounts of calcareous algae, which ex-plains further the low carbonate content of these sediments. The method used to determine the amount of carbonate present was that of digesting a five gram sample in dilute hydrochloric acid at moderate temperature for two hours, then filtering, washing, drying and weighing and computing the amount of carbonate by weight loss. For sand fractions, an - 66 -estimate was also made by placing small amounts of sediment in acid and counting the effervescing grains under the binoculars. This latter method appears to work satisfactorily where the calcium carbonate content is small. In large scale projects where adequate equipment is available, some such method as the titration procedure of Vesterberg (Twenhofel and Tyler, 1941, » p. 124) would best be employed. However, Trask (1932, p. 96) used the hydrochloric acid effervescence count method for the majority of tests, em-ploying a titration procedure and the weight-loss method only for a small percentage of the total analyses made. In studying long cores, sampling for calcium carbonate determinations should be carried out at intervals over the length of the core. Variations might reflect changes of salinity which in turn might be indicative of climatic changes: the more calcareous layers would represent more acid periods when evaporation was high and influx of terrigenous debris at a minimum, and layers of less calcareous content might represent the de-position of more humid periods when evaporation was low and influx of sedi-ments from the land was large. A complete study should include measurement of carbonate in solution as well as in bottom sediments (Twenhofel, 1933, pp. 68-76). Chemical Analyses Under this heading are included a l l types of chemical analyses, not already mentioned, which might be required to complete data on the mass properties of sediments and their environment. Products of chemical transformations taking place in the sea can be examined chemically as well as mineralogically. Revelle (1950) gives an account of chemical and bacteriological studies of sediments carried out to determine chemical and biological conditions under which diagenetic processes are occurring in bottom sediments. As part of his work, he determined the amounts of - 67 -hydrogen sulphide present at various depth and related this to qualitative and quantitative determinations of bacteria and to ion compounds. He also measured the amount of oxygen consumed in stored water samples containing some mud i n suspension, thus finding the amount of organic matter available for oxidation by micro-organisms, and concluded that an appreciable fraction of the total organic matter in the sediments was readily decomposable. It might also be desirable to have quantitative determinations made of ferric and ferrous oxides, silica and alumina. A complete chemical analysis is often reported for deep-sea sediments; but i t is suggested, that for sediments such as those occurring in Bute Inlet, t;h.ere the clay fraction does not predominate and the observable individual mineral constituents, even though very small in amount are diagnostic, mineralogical data is of far more value than chemical analyses. In other types of sediments, however, chemical analyses would be essential. Chemical procedure can be used to advantage where chemical changes sueh as the formation of zeolitic, phosphatic and manganiferous nodules are evident and also on glauconitic sediments. In waters of high alkalinity, induced by the decomposition of large amounts of organic matter and subsequent reduction of sulphates to sulphides and carbonates, these ohanges may be occurring on a large scale, and i t would be necessary to have an estimate of the nature and amounts of such compounds as those of iron and manganese. Insoluble residue analysis is an important part of examinations of oalcareous sediments (Leroy, 1951, p. 142). Hydrocarbons which are in a fluid state in sediments may be dissolved in a cold solvent and their quantity estimated by any one of several methods (Hawley, 1929, pp. 303-328). In unconsolidated materials of terrestrial deposits, where soil forming processes are under way, complete chemical data can be expressed in terms - 68 -of such ratios as si l i c a to alumina, s i l i c a to iron oxide, potash plus soda to alumina. Such data gives an idea of the extent of the soil profile de-velopment, which in turn is a product of climate and other soil-forming factors. A geological application might be made of this chemical ratio data to the study of Recent and Pleistocene deposits in order to gain data on the history of these deposits subsequent to deposition. The nature and extent of chemical analyses w i l l therefore depend upon the type of sediment being examined. Of considerable interest is a periodic appearance in Bute Inlet of a waxy substance which is carried on the surface of the water. It is suggested by some investigators that this may originate inland, where there are dense growths of Pinus banksiana, and be carried seaward by the Homahko River. The organic matter reported on in this investigation is a total content, waxy and non-waxy; better understanding of the origin of the waxy material might be gained by doing many analyses-for total-organic matter and for ether soluble material as well. The latter would consist principally of fatty substances and a correlation of these two criteria might reveal significant facts on the distribution of the ether solubles throughout the length of the inlet. Wilson (1946, pp. 110-120) deals with the suitability of fossil spores and pollen in correlation work and the methods of studying them. The phenomenon occurring periodically in Bute Inlet may be an instance of the introduction of these materials into recent marine sediments. It is suggested, therefore, that a detailed examination of a large number of Bute Inlet samples for, not only total organic matter content, but also for a breakdown of this component of the sediments into its various constituents would be worthwhile as i t would provide a complete record of the nature of organic substances in sedi-ments of a British Columbia fiord, and also might lead to some conclusions on the value of plant-derived materials in geologic correlations. Compressibility The process of consolidation is pertinent to an understanding of geo-logic structures and i t is also a factor to be considered during the design of engineering-structure foundations. Consequently, laboratory work on un-consolidated sediments of an argillaceous nature should include an examination of compressibility, and quantitative results should be related to the type of clay minerals, moisture conditions and mechanical analysis data. Such tests carried out in a geologic laboratory can assist in field structural studies. Compressibility tests are presently most widely used i a soil mechanics investigations of foundation materials. The value of relating compressibility characteristics to mineralogical data is evident, regardless of whether the immediate purpose lies in scientific structural studies or in engineering appraisals of foundation materials. Some Conclusions Regarding Physical and Chemical Properties Some of the properties discussed above are of fundamental geologic significancej others are more closely related to technological considerations yet a l l are closely inter-related. A complete appraisal of a body of sedi-ments might necessitate analyses of a l l of these properties. The nature and scope of the project w i l l determine the program carried out. In general i t would seem that whereas examination of recent marine sediments should emphasize the purely geologic criteria, a geologist's appraisal of an en-gineering problem should include the testing of some of the more techno-logical features, as many of the latter properties are only clearly under-stood in the light of fundamental geologic concepts. The inter-relationship; of a l l of these properties is significant. - 70 -Bonding strength is a function of cohesiveness, which in turn is closely related to impact resistance. Texture helps to explain a l l three properties, as the smaller the particles, the more numerous are the points of contact. Therefore the bonding effect, due to the glue-like action of whatever clay mineral is present, becomes greater. Then again, the strength character-istics are governed by the percentage of clay and its relation to overall textural features. The cementing action of a given percentage of clay is greater in s i l t than in sand, but beyond a certain point further additions of clay do not increase cohesion. Cohesion diminishes with increase in moisture content. Moisture in turn may be related to base exchange capacity. Cation content has a controlling effect on cohesiveness: the higher dispersion in sodium and lithium sediments results in a large number of points of contact and therefore in greater cohesion. There is a direct relationship between exchange complex and pH. Oxidation - reduction potentials, which bear a olose relationship to pH, are also a measure of conditions which determine when organic matter w i l l accumulate with sedi-ments. Reducing conditions are responsible for some of the colors of sediments. Water and clay mineral content are two variables which control such properties as shrinkage, plasticity and structure. Texture is an indicator of amount of clay content in relation to other minerals and therefore of the properties which are largely functions of clay minerals. The character of the cation influences the thickness of clay-mineral flakes with consequent result on other properties: the sodium bentonites w i l l swell markedly whereas the hydrogen bentonites swell very l i t t l e . Plasticity, bonding strength and shrinkage are functions of clay mineral composition, the nature of exchangeable bases and of the amounts of clay minerals present. Shrinkage is also a function of clay-mineral type and water con-tent. Strength varies with the character of exchangeable bases: green - 71 -strength is higher for hydrogen clays than for clays carrying sodium. Strengths are also closely related to particle sizes and therefore to tex-ture. Thus i t can be seen that any one of the mass properties of sediments bears a direct relation to one or more other properties. While some may be considered to be more fundamental geologic properties than others, i t would appear that geologic laboratory work of any scope should include tests of the mass properties here outlined so that results can be linked to data obtained from mineralogical examinations and mechanical analyses. - 72 -PART IV M E C H A N I C A L A N A L Y S I S Purposes and Uses. Sizing by mechanical analysis procedures involves the separation of sediments into a number of fractions. The average size of the particles i n each fraction bears some definite ratio to that of other fractions. The purpose and significance of such an analysis provides a means of describing clastic sediments i n a more or less precise manner, and of studying the influence of grain-size distribution on porosity and permeability, of ob-serving the relation between the dynamics of stream flow and the transpor-tation of particular minerals, of making quantitative studies of facies changes and correlation problems and of identifying the agent or environ-ment responsible for the origin of the sediment (Pettijohn, 1949, p. 30). A great deal of experimentation i n mechanical analysis procedures and i n the interpretation and presentation of the data so gained has been carried on by geologists, pedologists, c i v i l engineers and others, but there appears to be l i t t l e unity of thought on methods or on interpretations. At the same time, the entire procedure has become more complicated as refine-ments i n methodology have developed. A mechanical analysis permits the expression of sizing and of sorting i n graphical or mechanical terms. If technological purpose i s to be served, possibly the matter of classification of a sediment according to major size-types i s a l l that i s required from these results. S o i l mechanics work w i l l require, i n addition, the relating of these results to porosity and permeability and possibly to such other characteristics as p l a s t i c i t y , compaction strength and shearing. Fundamental geologic studies w i l l require the projection of sizing and sorting results into a l l phases of sedimen-- 73 -tation, ranging from classification to environment. Examples of this type of study are those compiled in the symposium on Recent Marine Sediments (Trask, 1939, 736 pp.) and numerous articles in the Journal of Sedimentary Petrology, such as the report of an investigation of bottom deposits of the Red Sea (Shukri and Higazy, 1944) and a study of the sediments of Lake Elsinore (Mann, 1951). Because there is such a variety of procedures which might be used, each of which could give significant differences in results from those of another method, i t would appear necessary to select a procedure based on fundamental concepts and one which is also most suited to the problem in hand. Then the procedure should be carefully standardized and the results expressed in terms of the method used. Preparation provides for maximum separation and dispersion of the Individual grains, and fractionation sorts these particles into various size classes. Pettijohn (1949, p. 85) gives a chart showing the constituents of unconsolidated sediments in terms of size grades. The commonly accepted boundary between s i l t and clay occurs at two microns, and between s i l t and sand at 62 microns. Separation of sand particles from fine particles can be done by sieving. Sizing of fine particles i s , in the main, based on Stokes Law, which expresses velocity of settling in a fluid in terms of the attraction of gravity, the square of the diameter of particles, the difference between the density of the particle and that of the flui d , and the viscosity of the fluid. The suitability of Stokes Law as a basis for determining settling rates is discussed by Krumbein and Pettijohn (1938, pp. 95-117) and Taggart (1951, pp. 69-85). Rubey (1933) advocates a com-bination of Stokes* Law and the impact formula which when combined in a general equation can be used to compute settling velocities of large and small grains. - 74 -A breakdown of sizes into the various grade scales was worked out by Ddden (1914, pp. 656-680), who laid the foundation for most grade scales as used today, by enunciating his laws of sedimentation: the laws of the chief ingredient, of decreasing admixture of the sorting index, and of the secondary maximum. Of the various methods, a l l of which are based on settling laws, which have been developed for mechanical analysis, those which have had widest use are decantation, rising current elutriation, air analysis, sedi-mentation procedures using automatic weighing machines, sedimentation methods using manometric tubes, pipette and hydrometer methods, centrifugal sedi-mentation, and various settling tube arrangements such as the Puri Silto-meter. Sand fractions are generally sized by sieving. Doeglas (1946, pp. 19-40) advocates extensive use of mechanical analysis as an aid to the determination of facies. He makes extensive claims for the method in environmental studies but admits that mechanical analysis of a large number of samples from various environments in different parts of the world must be made in order to arrive finally at universal sedimentary types as based on size and frequency distribution. A simul-taneous study of size frequency distribution and structure on a regional scale in many environments will give useful data for the interpretation of fossil deposits. Mechanical analysis procedures are time consuming; consequently i f they are to be carried out on a large scale, some system must be devised to facilitate the gathering and compiling of information. In carrying on a study of the transmission of sound in the ocean for the Division of War Research, Emery and Gould (1948, pp. 14-23) analyzed 10$ of their samples by sieve and pipette methods, and then set up standards in labelled glass vials - 75 -which were arranged in a gradational series. They then analyzed the re-maining 90% of the samples by comparison with these samples, comparison of known and unknown being made under the binoculars on the basis of median diameter and sorting. They also used a method of coding to express the approximate weight - frequency distribution of the various size grades in the samples. The method was found to be satisfactory in well-sorted marine samples, and the results of their mechanical analysis data, when combined with depth and bottom topographic data, contributed considerably to an understanding of underwater sound transmission. Preparation of Sediments for Mechanical Analysis The term preparation is meant to include sampling, disaggregation and dispersion. Sampling takes place in two stages: representative material is obtained from the source beds, this in turn is further portioned in the laboratory in order to obtain suitable amounts for the several in-vestigations being conducted. The success of measuring the texture of sediments by settling procedures is dependent upon the completeness of dispersion. The most stable suspensions are formed by clays saturated with highly hydrated ions such as lithium or sodium. The object of preliminary treatment is to free individual particles of minute size from their coating of colloidal material. This is done by saturating them with highly hydrated ions. Peptizers, such as sodium hydroxide, are added to sediments in solution in order to neutralize the exchangeable hydrogen ions. Clay particles in suspension carry an electric charge, usually negative. Each particle is surrounded by a double layer of ions - an inner layer of negative ions firmly attached to the surface and a corresponding layer of electrostatically attracted, but to a certain extent movable, ions. The inner layer is formed of 0 and OH ions; the ions of the outer layer - 76 -constitute the exchangeable bases. If the outer layer consists of hydrogen ions, the particle is a clay acid. The state of coagulation of a sediment or sediment suspension depends on the nature of the absorbed ion and on the interaction of these ions with those of the dispersing agent. These con-cepts aid in the selection of suitable dispersing techniques. Clay cannot be completely dispersed into single particles, regardless of the dispersion technique, as the smallest grains will always be aggregates, the sizes of which vary with the nature of the ions present. As a l l dis-persion processes involve base exchange phenomena, sediments of varying origins and composition and cation saturation, will respond differently to the several types of peptizers commonly used. This makes the comparison of the results of mechanical analyses difficult, unless the results are stated in terms of the method used. Marine sediments should be washed with distilled water to remove the soluble salts. At the same time, easily removable bases will be, to a certain extent, replaced by H ions and maximum dispersion cannot be attained as long as the sample Is partly saturated with H ions or possibly divalent ions. A good peptizer fixes the calcium ions and neutralizes the H ions. Such a peptizer is sodium carbonate. The main problem, however, when the base exchange capacity is unknown, is to find out how much peptizer to add. Too much electrolyte may be as detrimental to good dispersion as too l i t t l e . One way of being sure of the amount to be added i s , therefore, to make an actual determination of base exchange capacity. Calcium and hydrogen are the most active coagulatersj consequently a determination of the amount of these ions would be necessary. Such a procedure, however, would be im-practical where a large scale project is contemplated. Several dispersion routines are in common use. One involves simply adding some arbitrary amount of peptizing electrolyte, such as ammonium - 77 -hydroxide or sodium oxalate, to a water solution of the sample and then carrying out physical dispersion either by shaking in a reciprocating shaker or stirring in a electric drink mixer. Where the material has only a small percentage of clay fraction, the type and amount of electrolyte is not of much consequence; but, as pointed out above, a large clay, or even s i l t fraotion suspension may be easily coagulated i f the dispersing tech-nique is inappropriate and the electrolyte fails to perform its function of increasing charges on individual particles to aid dispersion. To add a prescribed amount of electrolyte to one sample because i t was found to be suitable for another is not an insurance that dispersion w i l l be attained or maintained. In spite of this defect, the widely used Bouyoucos method consists of adding 5 c c . of a solution of sodium silioate or water glass, having a soil hydrometer reading of 36, and 5 c.c. of saturated and filtered sodium oxalate to 500 c.c. of distilled water into which a 50 gram sample is placed, allowed to soak for 15 minutes and then dispersed in an electric drink mixer for about 20 minutes i f fine material is being tested or 5 minutes If sand. (Bouyoucos, 1935) A second main approach to the problem of dispersion i s to determine experimentally the most suitable dispersion media. This involves placing, say % gram of a representative sample into each of a set of test tubes and f i l l i n g them with such peptizers as N/25, N/50 and N/lOO sodium carbonate; dilute ammonia (400 ml. distilled water added to 40 ml. of freshly pre-pared 33$ ammonium solution); N/100 ammonium hydroxide; N/100 sodium oxalate; sodium silicate (0.5 ml. of N/5 sodium silicate in 500 ml. distilled water); N. sodium hydroxide; N. ammonium carbonate; N. potassium or sodium chlorides; ammonium sulphate; lithium hydroxide; sodium hexametaphosphate (made by - 78 -dissolving 2 grams of sodium hexametaphosphate and 0.5 grams sodium car-bonate in one l i t r e of distilled water). Any number of these peptizers may be tried in experimentation. The suspensions are well stirred and left overnight. A few drops of each suspension are examined under the microscope and decision can then be made as to which is the most suitable peptizer. Coagulation w i l l be apparent by the formation of clusters of grains; dis-persion is complete i f individual grains are discernible, with smallest grains showing Brownian movement. Shukri and Higazy (1944, Vol. 14, No. 2, pp. 55-69) give results of following such a procedure, and conclude that ammonium solution was the most suitable peptizer for the particular sedi-ments that they were examining. The Bute Inlet sediments were studied in this manner and i t was found that N/100 sodium oxalate and sodium hexametaphosphate were suitable pep-tizers. The third general approach to dispersion is centered around actual experimentation with base exchange phenomena. Some techniques involve the use of an acid to remove exchangeable bases before a dispersion agent is added. These techniques, however, are not suitable for marine sediments as the acid removes acid-soluble material and thereby distorts the final mineralogical results. However such a method as that advocated by Purl (1949, pp. 274-282) does not have this objection. The basic contention of Puri is that the only way of attaining maximum dispersion is through the conversion of the soil or sediment into a sodium saloid of pH 10.8. Some materials show maximum dispersion at lower pH values, but a l l show i t at 10.8. Furl's conclusions are based on well-established chemical principles and on many tests, and his treatise is possibly the most authoritative on the whole subject of dispersion. - 79 -The procedure used in the preparation of Bute Inlet sediments con-sisted f i r s t of weighing a sample - about 50 grams - in its natural state, at the same time setting aside a representative sample for a moisture de-termination. The moisture determination can be made by weighing, drying overnight in an oven at 105°C., cooling in a dessicator containing phos-phorous pentoxide as a drying agent, and then weighing again after the sample has cooled. The test sample is washed with distilled water to remove water soluble salts, soaked in the sodium hexametaphosphate and sodium carbonate solution, referred to above, for a period of about 12 hours, placed in a large dish and completely disaggregated by using a s t i f f brush, stirred in a electric drink mixer for 10 minutes, passed through a 250 mesh Tyler screen, and then is analyzed by the hydrometer method. The degree of dispersion is checked before commencing the hydrometer analysis by examining several drops of the suspension under a microscope. If coagulation has occurred, this may be remedied by diluting the suspension and heating nearly to boiling. Although this method appeared adequate for the recent marine sediments being examined, other types of sediments and soils might require a more rigorous treatment such as that suggested by Truog et. a l . (1936). It i s , of course, an open question as to whether the method of selecting a dispersing technique by experimenting with a number of peptizers, as done in this project, is adequate, or whether the strict routine prescribed by Puri should be followed. It would seem that in the case of relatively easily dispersed marine sediments, experimental selection of a peptizer,is justi-fied, but that in dealing with certain terrestrial sediments and soils, consistent results could only be assured by adhering closely to chemical and electro-chemical principles. It can be concluded that the use of some arbitrary method for any one of a number of sedimentary types is not con-ducive to good results. - 80 -Mechanical Analysis of the Sand Fraction Mechanical analysis can be divided into two distinct operations. The most complete and most common procedure involves separating the sand portion into fractions or grades by means of sieving, and measuring grain size distribution in s i l t and clay fractions by some method based on settling rates in a fluid. Alternatively, in sediments where the clay fraction i s negligible, sand and at least part of the s i l t can be classified as to size by a settling procedure. It is proposed to consider here methods by which the sands and coarser s i l t s can be sized. The Wentworth grade scale (Wentworth, 1922, p. 382) places the boundary between sand and s i l t at 1/16 mm grain size. The Tyler standard screen scale sieve series uses the 200 mesh screen, with an opening of 0.07A mm, as a base and increases and decreases along the scale with a ratio. Consequently, the 250 mesh Tyler screen provides a means of making a separation of sand and s i l t in accordance with the Wentworth classifi-cation at 0.062 mm. The material passing through this sieve can be analyzed by sedimentation methods; that retained can be dried and separated into various grades by Tyler screens. Sieving classifies by size only; i t disregards specific gravity, particle shape and volumetric size. Consequently sieving of sediments having a high percentage of tabular minerals, such as mica flakes, i s not accurate, although accuracy of sieving does, in general, increase with approach to sphericity. In spite of its limitations, sieving is used be-cause of the speed and convenience of the method and its ability to give at least a rough estimate of size distribution. The method of making a sieve analysis can be outlined as follows. The sediments retained on the 250 mesh screen, following wet sieving, are dried in an oven for about A hours. The sample is weighed or measured - 81 -volumetrically in a graduate, and then is placed in the uppermost sieve of a suitable bank of sieves. (See Plate I, A). The bank is placed in the Rotap Machine and shaken for 10 minutes. Then the contents of each sieve are poured onto a large sheet of paper from which they can be poured into a weighing pan or a measuring graduate. The weights or volumes are recorded and, as a check, the total weight or volume of a l l fraction is again taken. For weight, no more than j$ loss should be found. For volumetric measure-ments, there should be an increase in volume by about 1 to 2%. If sieving is to be done on a large scale, the volumetric method is quicker than weighing, but care is required in measuring and a standard procedure, such as tapping the graduate lightly on a soft block a specified number of times to get standard compaction, should be adhered to. In addition, specific gravity and specific weight tests should be made on the complete sample and on individual fractions from time to time. A sieve analysis was done on four sand samples from the McKenzie River Delta. Table V demonstrates the method used in preparing sieving data for graphical analysis and Figure 3 shows the cumulative-frequency curves drawn from this data. Sorting characteristics are dealt with in Part VII. The sand fraction of some of the Bute Inlet samples was of such small quantity that estimation of size distribution was made more con-veniently under the microscope. The other samples were sized by screening. These data were combined with hydrometer runs and are shown in Figures 1G and 6. Settling methods take into account more of the hydraulically signi-ficant features of sand than does sieving and consequently they are of more value as a research procedure. Emery (1938, pp. 105-111) deviBed a method for classifying sands in a settling tube. The Emery tube is 21 mm. inside diameter and 164 cm. long. At the bottom, the tube narrows to 7 mm. inside - 82 -TABLE V Size Analysis - Mackenzie River Sediments Sample at Station 35 Sample at Station 17 Mesh Mm. Wt.-gms 3. % % Smaller Wt.-gms. % % Smaller 20 .833 100.00 100.0 28 .589 .21 1.91 98.09 .22 2.17 97.83 35 .417 .48 4.32 93.77 .46 4.53 93.30 48 .295 .75 6.84 86.93 4.40 43.11 50.19 60 .246 1.05 9.52 77.41 2.02 19.89 30.30 100 .147, , 4.45 40.55 36.86 2.75 27.05 3.25 150 .104 2.15 19.56 17.30 .15 1.48 1.77 200 .024 1.25 11.42 5.88 .12 1.18 0.59 250 .061 ,65 5.88 0.00 ,06 .59 0.00 10.99 10.18 Sample at Station 11 Sample at Station 30 28 100.00 100.00 35 .417 .08 .84 99.16 .12 1.06 98.94 48 .295 .80 8.25 90.91 .21 1.85 97.09 60 .246 1.65 17.19 73.72 .29 2.53 94.56 100 .147 6.75 70.69 3.03 2.10 18.50 76.06 150 .104 .20 2.09 0.94 2.68 23.60 52.46 200 .074 .09 .94 0.00 4.20 37.04 15.42 250 .061 lt75 15.42 0.00 9.57 11.35 diameter and is closed with a stopcock. The narrow portion of the tube above the stopcock is engraved with mm. divisions from which the cumulative heights of sediment are read. In assessing the value of the Emery tube, Poole, Butcher and Fisher (1951) found that time was saved by making mechani-cal analyses by means of this settling tube in place of sieving, that median diameters are reproducible to within less than 1% for medium to very fine-grained sands in which mica makes up only a small fraction of the sample, that the sorting determination was less reproducible, that for coarse sands the sieve method is much more accurate than the settling tube, and that the settling tube analyses yield equivalent diameter rather than the geometric diameters obtained by sieving. As these two measures differ most when platy Figure 3. SIEVE ANALYSIS - MACKENZIE RIVER SEDIMENTS 5? <D Go I - 83 -material or minerals other than quartz or feldspar make up an appreciable portion of the sample, a method which records i n terms of equivalent diameters i s of more value i n measuring the effects of erosion, transpor-tation and deposition of sediments than one recording i n terms of geometric diameters. Doeglass (1946, pp. 19-44) describes and gives a sketch of a similar apparatus; but instead of making volumetric measurements, he designed an instrument, consisting essentially of a 200 cm. tube, whioh has at the bottom a disc suspended by a steel wire from the arm of a balance placed above the cylinder. The arm i s graduated to give a weight reading and con-sequently the percent by weight of the material that has settled on the disk can be read at any time interval. He found that between 500 and 5 microns the error i n analyzing duplicate samples was less than 2%, The instrument is not suitable for handling particles of sizes outside this range. Four gram samples are used. A third design of apparatus using the settling principle i s the Purl Siltometer (See Plate I, E). This i s also a 200 cm. tube, but differs from the Emery and Doeglass tubes i n having an arrangement for collecting the sized particles i n groups as defined by their time to settle the 200 cm. A circular tray with 20 separate sections can be rotated at intervals to catch the different fractions as they are deposited from the bottom of the tube. By comparison of the time for particles to settle with the time for quartz spheres to settle the same distance, the particles can be classified i n terms of the diameter of hypothetical quartz spheres. Thus i n this method, as i n those of Emery and Doeglass, a l l factors affecting settlement are taken into account, suoh as size, density, and particle shape. However, the Purl apparatus i s superior to the other two i n that there is provision for collecting the various size fraction; each size fraction can then be studied - 84 -mineralogicaHy and correlations between mineralogical and size data worked out. Measurement of the size fractions can be made volumetrically or by weight. Puri (1949, pp. 259-263) describes the apparatus in detail and the technique of use, and also gives a table relating settling times and temperatures to particle diameters. This apparatus was investigated and several runs made. Figure 4 shows analysis data and curves for a beach sand sample as obtained by the s i l t o -meter method and by sieving. Table VI shows particle size in terms of settling times for several temperatures as abstracted from Puri (1949, p. 263) and from a U.S. District Engineering Office pamphlet (1948, p. 41). Although the Puri Siltometer is not effective for large scale pro-jects, i t would appear to be an excellent piece of apparatus for doing research work where data from mechanical analyses and mineralogical studies are to be related. Ten gram samples are used, and excluding time for drying the sample, one hour should suffice for the running and weighing of two samples. The mechanical limitations of the apparatus center about the tripping device at the top of the tube, which is designed to drop the sample uniformly into the column of water, and the rotation of the catching tray. With proper adjustments and a l i t t l e practice, errors incident to these two devices are not thought to be serious. Figure 4 shows that a l -though the median diameters for sieve and siltometer curves are very close for this particular sample, the curves diverge on either side of the median, whioh would be reflected in statistical analyses carried out in terms of five parameters by the method of Inman (1951)• Although called a siltometer, the apparatus is not suitable for handling sediments of less than 60 microns in grain size. An apparatus for classifying 100 to 125 samples of sand per day is described by Uppal and Singh (1951, Vol. 32, Ho. 6). The design is based - 85 -TABLE VI Data for Siltometer Operation Diameter in Mm. of Particles Settling Through a Vertical Column 200 cm. Long Time T e m p e r a t u r e Seconds 15.GC 20°C. 25°C 30°C. 6 2.40 2.30 10 1.29 1.23 14 .91 .86 18 .72 .67 22 .55 .51 26 .588 .562 .540 .518 30 .515 .492 .472 .454 34 .459 .438 .421 .404 38 .416 .397 .380 .365 42 .381 .363 .348 .334 46 .352 .336 .321 .308 50 .328 .312 .299 .287 58 .290 .276 .264 .253 66 .262 .249 .237 .227 76 .235 .223 .213 .203 86 .214 .203 .194 .185 96 .198 .187 .178 .170 106 .184 .174 .166 .158 136 .155 .147 .139 .133 166 .137 .129 .122 .116 196 .123 .116 .110 .105 376 .085 .080 .076 .072 556 .069 .065 .061 .058 upon the fact that sand particles, when dropped across a horizontal stream of air flowing at constant speed, separate and distribute themselves according to their sizes. This apparatus is suited to handling material in the size range of 80 to 640 microns. In addition to the part played by mechanical analysis procedures in fundamental sedimentation studies, size and sorting data is important in geologic investigations required for the design of beach engineering pro-jects. The geologic viewpoint emphasizes dimensions and character of the beach, source of beach materials, slope processes, shore cycle erosion arri physiographic classification (Krumbein, in Application of Geology to Engineering Practice, 1950). The matter of beach slope and sand size is of Per Cent Smaller - 86 -considerable importance both in the design of beach protected structures and in the development of a r t i f i c i a l beaches with imported sand (Bascon, 1951, pp. 866-874.) • In estimating the cost of the excavation of unconsoli-dated sediments in road construction work, geologic field work supported by-laboratory examinations is often of value. Mechanical analyses may be re-quired in such an estimate (Bean, in Application of Geology to Engineering Practice, 1950, pp. 181-193). Hydrometer, Pipette, Decantation, Centrifuge and Microscope Methods. There are five principal methods in common use, for making size analyses of fine-grained sediments: hydrometer, pipette, decantation, cen-trifuge and microscope methods. Other methods, such as air and rising current elutriation, Oden's sedimentation balance method, and procedures using manometer tubes are of historic interest but are l i t t l e used today. Krumbeln and Pettijohn (1938, pp. 147-176) give a comprehensive survey of these older methods. Of the several procedures in current use, the pipette method is generally accepted as the one which gives the most accurate results, although the hydrometer is used more widely. A l l of these present day methods, except mechanical analysis by microscope, are based on settling rates. Hydrometer Method.- The hydrometer has•come -in to wide use for making size analyses of sediments because of the adaptibility, simplicity and accuracy of the technique*. Bouyoucus (1927, pp. 343-363) f i r s t proposed the use of the hydrometer and later improved the technique (1935, pp. 481-485). It has subsequently been checked by many investigators. The equipment consists of a one-litre cylinder and a hydrometer calibrated to read grams of sedi-ment per l i t r e in the suspension at various intervals of time. - 87 -The hydrometer method was used for a l l mechanical analyses made of Bute Inlet samples. Several samples were also sized by centrifuge. The following hydrometer procedure was used: after preparation of the sample, addition of peptizers, stirring in electrio mixer, and wet sieving to remove the sand fraction, the silt-clay suspension was poured into a l i t r e cylinder and the volume made up to 1000 cc by using the prepared hexametaphosphate solution (2 grams of sodium hexametaphosphate and 0.5 grams of sodium car-bonate per l i t r e ) ; the palm of the hand was placed over the mouth of the cylinder and the cylinder shaken vigorously, turning the cylinder completely upside down and back several times; the cylinder was placed quickly on the table, the time noted, the hydrometer placed in the suspension and the f i r s t reading taken at the end of one minute. If there is inclined to be any frothing, a drop of amyl alcohol can be added as soon as the cylinder i s placed on the table and the froth w i l l olear in time for the f i r s t reading. It ,was found advisable to take readings at the end of each minute for the f i r s t five minutes without removing the hydrometer. It is impossible to insert and remove an object which has one-half the diameter of the cylinder without disturbing the suspension; the error introduced by allowing particles to collect on the hydrometer during the f i r s t five minutes is much less than that due to mixing in the upper layers of the suspension. After the f i f t h reading, the hydrometer was removed, washed free of s i l t and set aside t i l l the 15 minute reading. Readings on Bute Inlet sediments were taken at one minute intervals during the f i r s t five minutes, at 15 and 60 minutes, at 12, 24, 48 and 96 hours. Plate I, C shows the hydrometer tubes and the constant temperature bath into which the tubes can be placed after the f i r s t five readings are completed. Temperature of the suspension was kept at a l l times as close to 67°F as possible, but temperatures were taken after each reading and corrections made, because the hydrometer is calibrated at 67°P. H Y D R O M E T E R C O R R E C T I O N S F O R B O U Y O U C O S S O I L H Y D R O M E T E R S m C o r r e c t i o n F a c t o r K F, ore. ©1 ts-j£tos3fctyrj5 C o r r e c t i o n F a c t o r K N - 8 8 -The chart, Figure 5 simplifies the temperature correction. This chart also provides for a correction for changes in viscosity, Kh, of the suspension with temperature, and a correction, Kg, for specific gravity variations from 2 .65 . A fourth factor, KL, gives a correction for the elevation of the hydrometer and is based on hydrometer readings. Table VII shows the data recorded and the method of computing as carried out for sample number 20. Figure 6 gives the hydrometer curves for 20 Bute Inlet samples. A defect of the hydrometer method as compared to the pipette is that the former does not measure the concentration at one point, but gives an average density of a large section of the sedimentary column. This section moves with changing concentration of the suspension, which affects the resting point of the hydrometer. Nothing can be done to correct the f i r s t of these defects, but the application of the factor of correction, E L , as shown on the graph of hydrometer corrections, is a means of correcting the second affect. The basis of the hydrometer method rests on the single assumption that the average density of any section of a sedimentary column is equal to the density at its middle point. Although this is an unsound theoretical background, work by Purl and others, in comparing the hydro-meter and pipette methods, has shown general agreement between the two. Thus while there is no theoretical reason why the density gradient of a section of sedimentary column should show symmetry, repeated experiments by many investigators have shown that i t does and the results of hydro-meter analysis are now accepted by many as being truly representative of size distribution of sediment particles. It is recommended that a hydrometer calibrated to 10 grams be used for analysing small samples, particularly when making textural studies over the length of a core at regular intervals. F i g u r e 6 C U M U L A T I V E - F R E Q U E N C Y C U R V E S BUTE INLET S E D I M E N T 5 C L A Y S » U T S A M P GRANULE j 1 Li. ( \ | i 1 1 / i i i ! I V jo/ • •** j 9c Of * 6o J . <c no " Co So V z ol Ui o o o b I • e <?0 tt j . . h S o 7 S88 o a 04 '.n o o o 6 2 ? o o « • O ° 0 6 d 6 °©bb °*o - £ H S ^ in o o o o CD J) R-I 1 \+, i ./I / 1 1 OL ZO lo o o S g o § o - - * £ 17 ** 1/ H P * / f ^- Tift-J o o 9o -I a: £ To Co III UJ S C R E E N S - P U S H io a 9o a So h 10 Ui 0- xo (O j T Y I . E R ifOiOO'SO loofeff 48 3S l g l o lo S J V A / 1 > 1 -a — » 0 o i g o o §§§ —1—TT 0 o Ci O o o b ' 0 0 o o o o o" o ci o o o o o 0 — i _ . n 1 1 1 r I O a Q -r G OO O' OOOO.'" o o o ^ CD -r > i i - 1 — "2 S I P H I ^ 3 e U N I TS' -i -3 - 89 -Pipette Method.- The pipette method, in spite of the popularity of the hydrometer method, is considered to be the standard to which a l l other methods are compared. The essential pieces of equipment are a 25 ml. pipette, a l i t r e graduate, several 50 c.c. beakers, a hot plate, an analytical balance and the equipment and chemicals described in the section on pre-paration. The procedure of preparation and of placing the suspension in a l i t r e cylinder is the same as that carried out for the hydrometer method. In the pipette procedure, a 25 ml. sample is drawn off from a predetermined depth and at a given time and i t is then evaporated to dryness. The weight of the residue, multiplied by the ratio of the pipette volume to the total suspension volume, wi l l represent the total volume of material having settling velocities less than h/t, where h is the sample depth and t the time of sampling. Krumbein and Pettijohn (1938, p. 166) give a table for times of sampling in terms of particle diameter and describe a pipette pro-cedure. Many workers have described pipette procedures, but possibly the most complete schedule of any is that of Rittenhouse (1939, pp. 89-102). He gives details and a complete l i s t of equipment on a procedure that w i l l permit the running of 48 samples by one man and two part-time assistants in a 40 hour week. Samples used are 15 to 25 grams. The pipette method requires good laboratory facili t i e s and very care-ful work i f the accuracy which i t can give i s not to be offset by errors liable to enter into a rather complicated procedure. Decantation Method.- Like most other methods of mechanical analysis of fine-grained sediments, the decantation method involves the preparation of a suspension of sediment in a dispersed state so that each particle wi l l act as an independent unit in settling. The suspension is placed in a beaker or decantation tube and time is allowed for the settling out of particles of a given size. Then the suspension is decanted into another - 90 -beaker or tube and further time allowed for the next size grade to settle out. Wentworth (1926, pp. 39-46) describes the method in detail and pro-vides a table of settling times. Decantation was not used for size analysis as i t requires considerable repetition of each decantation and is therefore slow, cumbersome and inaccurate. However, in preparing samples of a maximum of two micron diameter particles for electron microscope examination, an application of the method was used in that particles greater than two microns were allowed to settle out and then a suitable sample was obtained by de-canting and allowing time for the settling out of suspended particles. Data shown in Krumbein and Pettijohn (1938, p. 166, table 16) were used in cal-culating settling times. Centrifuge Method.- The centrifuge method is actually a decantation pro-cedure which makes use of a centrifuge to speed up the settling process. This is a very convenient way of doing size analyses, and i t has the advantage of permitting recovery of the several size fractions for ultra-microscope or chemical analyses. The procedure used was that described by Trask (1930, pp. 581-599). Particles settle out under the influence of centrifugal acceleration and Trask gives the time of running and the speeds for making separations at 20, 10, 2, 2, 1 and 0.4 microns. Samples number 7, 9» 22 and 28 were sized by this centrifugal method. Table VIII shows the method of compiling data obtained from a centrifuge run, as illustrated by data for sample 7. Figure 7 is a graphical analysis of data obtained for the four samples. Trask1s procedures were used in the computation and plotting, the only departure being the naming of the 25% and 75% quartiles as Ql and Q3 respectively instead of Q3 and Ql, in keeping with prevailing practice of calling the 75 percentile Q3. Table IX summarizes statistical data taken from the curves and offers a comparison with similar data from the hydrometer curves of Figure 6. Within the limits HYDROMETER ANALYSIS / SJMPLE No. 2 0 , BUTE INLET SEDIMENTS TABLE 73! Time Hydrometer Temp. Corrected d Kg El Kn a Readings op Hydro Rdgs. a=.989 JL 1 min. 48.0 70.5 48.5 93.6 .074 .99 .440 .975 .032 2 " 43-5 44.0 85.O .055 it .450 M .025 3 40.5 « 41,0 79.1 .045 t i .460 II .020 4 " 38.5 tt 39.0 75.5 .039 n .465 tt .018 5 ? 36.5 « 37.0 71.5 .035 tt .470 tt .016 15 « 25.5 t» 26.0 50.8 .020 « .495 tt .010 60 » 21.0 it 21,5 37.5 .010 M .505 tl ,005 4 hrs. 15.0 it 15.5 29.5 .005 0 •575 41 .003 24 " 10.0 67.5 10.0 19.5 .002 41 .525 1.0 .001 48 V 9.0 t t 9.0 17.4 .0015 tt •530 1.0 .0008 12 » 7.5 n 7.5 14.7 .0012 tt .535 1.02 .0006 96 « 6.0 n 6.0 11.6 .0010 tt .540 1.0 .0005 Weight of Sample No. 20 =51.20 gms. (corrected for moisture) Erplahaatory Notes Stokes Law: V= 2/9 (D-D-Jgr2 t. d2 = 1800Vh g P ^ ) n Y in cm./sec. _________ D== density of particles (2 .65) or d = / 3 0 L n T D!= density of water (.998 at 20° C.) /(D-D1)t.980• n = viscosity - .01 poises. Kg _ 3 e Q g = 980 cm. per sec.2 JQ _ F I G 8 r = radius of particles Kh - 5 , d = diameter of particles a = S. G. correction (actual S. G. = 2.62) t = time of settling (in minutes) - 92 -TABLE VIII Centrifuge Size Analysis - Sample No. 7 Bute Inlet Sediments Approx. Dia. Volume Weight Weight *1 R2 R3 in Microns of Aliquot of Aliquot % 20 .40 .47 31.55 7.5 1.3 10 .5$ .65 43.55 30 5 5 .82 .97 65.05 120 20 .7 2 1.25 79.82 125 5 1 1.40 1.33 89.25 20 .4 1.55 1.47 98.66 125 Sands • — .02 1.34 . Total - 1.49 100.00 Silt-clay volume— 435 c.c. Total sample wt. 6.55 gms. Unaccounted r — r — r — - - - - - - - - o.06 gms. of sampling accuracy, the results of.these two methods appear to be reasonably consistent, especially for sample 7, which is the finest-grained of the four samples. Where large numbers of very fine-grained sediments are to be analyzed, the centrifuge'method would seem to be much the preferable of the two, but where only a few samples are to be sized, the hydrometer method appears to be the more adaptable, especially i f the size range of the material lies largely in the coarse s i l t category. The centrifuge method would find much use in a large-scale oceanographic project. The essential equipment' required for the centrifuge method includes a centrifuge, such as an International Centrifuge, Size #1, l/3 E.P., with a #242 Head and #395 Holders with rubber lining (see Plate I, D). The glass tubes for such equipment are described as A.S.T.M., pyrex, 100 ml. - 93 -TABLE IX Comparison of Centrifuge and Hydrometer Data, Bute Inlet Samples Centrifuge Curves Hydrometer Curves Sample No. 01 02 03 So. S i l t % Ql 02. 03. So. S i l t % 7 1.6 6.0 18.5 3.35 67.0 1.2 6.0 13.0 3.29 64.5 9 1.8 4.6 20.0 3.33 72.0 3.0 31.0 18.0 2.45 76.5 22 10.0 15.0 33.0 1.84 82.0 5.0 18.0 31.0 2.48 79.0 28 0.85 3.2 9.7 3.47 53.5 0.6 2.0 9.6 4.09 54.0 graduated at 1, 1.5, 2, 3, 4, 5, 6, 8, 10, 15, 20, 25, 50 and 100 c. c. This is the complete centrifuge equipment. Other equipment, such as an electric drink mixer and Tyler Sieves, are the same as required for hydro-meter and pipette methods. A l l of these procedures al3o require the customary laboratory supplies and equipment, such as glassware, a good balance and a drying oven. Dana (1943, pp. 21-27} proposes a method of size analysis in which the portion containing particles above l/l6 mm. in size is screened; the portion between l/l6 and 1/250 mm. is analyzed by the pipette method; and the sizing of the minus 1/250 mm. is done by the centrifuge method. The studies of Grim and Allen (1938, table 3) illustrate the use of the centrifuge as a means of fractionation in preparation for clay mineral analysis and as a means of relating size and mineralogical data. Microscope Size Analysis.- With a micrometer ocular, the microscope can be used to carry out size analyses of a sediment. Individual grains are measured and statistical analyses are made of representative samples. Similar data may be obtained from camera lucida drawings and from micro-photographs. Grassy (1943, pp. 47-57) describes a method of doing mechanical analyses of samples, too small to sieve, by measuring the intermediate diameter of grain - 94 -images projected on a ground glass screen. Charles (1951, pp. 452-459) present details of a photometric apparatus which will measure average par-ticle size and relative surface area of finely divided materials by deter-mining the weight of material necessary to produce a special degree of turbidity. This method provides a means of eliminating the great amount of labour involved in partiole size counting by microscope. Some Limitations of Mechanical Analysis The object of mechanical analysis is to determine the size-grade distribution of natural sediments as a basis for an understanding of their origin or properties, and also to permit a more adequate study of the mineral constituents (Grim, in Recent Marine Sediments, 1939, pp. 493). The mechanical analysis of sediments high in clay content represents the degree of diaggregation and may or may not be representative of the nature of the sediment. Consequently i f results of mechanical analysis are to be comparable, a standard procedure of dispersion must be used. If kaolinite is the chief clay mineral, mechanical analyses may be quite representative of the natural occurring material; for sediments high in montmorillonite, results w i l l vary considerably with the electrolyte used. Little is known concerning the state of aggregation of clay and colloidal particles that are suspended in sea water, but some investigators believe that fine-grained sediments when mixed with sea water tend to flocculate into units which settle with a velocity equivalent to that of quartz spheres between 5 and 15 microns in diameter (Sverdrop et a l , 1942, p. 955). This flocculation is related to the composition of clay minerals, particularly with respect to exchangeable bases and also to salt circulation of the water. However, although coagulated particles tend to settle faster, they may carry some water with them which reduces their effective density - 95 -and thus slows them down. The limitations of mechanical analysis procedures used today for oceanographic studies are therefore apparent, and i t would seem that more emphasis should be given in laboratory work to study of deposition under conditions more closely resembling actual marine environments. The measuring of settling rates and size distribution in tanks of salt water would give more representative results than the standard procedures now used which have the most complete dispersion possible as their objective. Furthermore, in reports of work that has been done on the sizing of recent marine sediments, l i t t l e is said regarding the actual methods of dispersion used in pipette, hydrometer and centrifuge proceduresj consequently the value of results of analyses of fine-grained sediments is open to question. However, in spite of objections to the ways of sizing sediments by mechani-cal means, there is l i t t l e doubt as to the importance of size distribution data in the study of recently accumulated sediments. These data afford a means of comparing conditions in different environments of deposition and of contributing to an understanding of post depositional mineralogic changes, thereby increasing the general knowledge of the histories of ancient sediments. - 96 -PART V M I N E R A. L O G I C A L A N A L Y S I S General Data obtained from field studies of sediments, from laboratory appraisals of physical and chemical mass properties, and from detailed in-vestigations of size distribution by mechanical analyses will indicate what types of mineralogical analyses should be emphasized; the data gained from mineralogical studies will account for many of the mass properties and the size distribution criteria; the summing and coordinating of a l l data ob-tained during the course of laboratory work will reinforce the conclusions indicated from field observations. This section on mineralogical analysis is concerned with procedures centering about the employment of binoculars and the petrographic microscope in the examination of the mineral and fossil content of unconsolidated sediments. Minerals of sedimentary masses may be classified in three ways: stable minerals such as quartz and to a certain extent the feldspars and micas; which survive the weathering process and which are released upon the breakdown of the parent rock; stable seoondary minerals formed by chemical alteration of the unstable primary minerals, such as the clay minerals and the hydroxides limonite and bauxite; and chemical precipitates from solution, such as chalcedony, carbonates, oxides, chlorides, sulphates, phosphates and certain silicates, the chief of which is glauconite. Pettijohn (1949, p. 85) gives a chart to show the constituents of the uncon-solidated sediments. The mineral assemblage of a sediment is the product of the source rock, conditions of weathering and of transportation, and post-depositional processes. Although over 160 minerals have been identified in sediments, the most common minerals are considered to be andalusite, apatite, augite, biotite, calcite, chlorite, diopside, dolomite, epidote, - 97 -garnet, hornblende, hypersthene-enstatite, ilmenite, kyanite, leucoxene, magnetite, muscovite, rutile, sphene, staurolite, tourmaline, zircon, felds-pars and quartz. These minerals form over 99% of the bulk of sediments, the latter two accounting for a very large proportion of sedimentary materials. Calcite, dolomite, muscovite, feldspars and quartz are classified as "light t t minerals and the remainder as "heavy", on the basis of specific gravities. The approach to mineralogical studies of sediments differs from that of igneous rooks. Sediments may contain more than a dozen different mineral species, whereas an igneous rock w i l l consist principally of a very few minerals. The composition of the feldspars in igneous rocks is a key factor in desoriptionj in sediments the exact composition of this mineral group is not of the same significance. More emphasis is given to the description of minor or accessory mineral species in sedimentary petrology than in studies of the plutonics. Generally speaking, the precise deter-mination of mineralogical composition in clastic sediments is of less importance than in igneous and metamorphic rock studies because several representatives of the main families, such as the pyroxenes, amphiboles and feldspars, may be present and their exact identification would be an endless task and of l i t t l e value. Of more importance are certain physical characteristics of a mineral or mineral group. Characteristic colors or shapes, or the presence of inclusions may be of considerable value where a large number of mineral grains is to be examined. The mineralogical examination of sediments w i l l therefore include identification of a l l mineral species, carried to the degree of precision considered adequate for the materials being examined, with particular attention being paid to any outstanding properties which characterize a given speoies. - 9a -The techniques of mineralogical analysis of unconsolidated sediments differ from those used for examinations of consolidated rocks in that a large percentage of microscope work is done on individual grains as opposed to thin section studies where observations are made on a fixed plane of the rock. The drawings and notes of Krumbein and PettiJohn (1938, pp. 414-452) and Milner (1940, pp. 116-263) are of considerable assistance in describing the physical, optical and detrital characteristics of mineral grains of sediments. Mineral analysis of unconsolidated sediments calls for preparation of representative samples, mineralogical descriptions of the constituent particles and the determination of mineral frequencies. Preparation in-volves disaggregation and clarification of grains, separation of grains of a sample into several groups by such methods as heavy liquid procedure, and sampling the several fractions further in order to get quantities suitably small for mounting. Mineral descriptions include identifications plus details on size, shape, roundness, surface texture and color. Quantitative studies of mineral species and their characteristics require statistical approaches in order that the large amount of data gathered may be systema-tized. Krumbein states (1945, p. 1234) that quantitative sedimentation may play its greatest role in respect to the more interpretive, as opposed to the descriptive, aspects of sedimentation in dealing with such questions as parent materials and source areas of sediments, agents of transportation and environmental conditions at the site of deposition; and in respect to these questions, the properties of particles enter directly into the problem of reading sedimentary"history. The Binocular Examination The binocular microscope has two main uses in the study of unconsoli-dated sediments. It may be used to make a preliminary examination of - 99 -samples as obtained from the f i e l d i n order to provide answers, i n part at least to the following questions. What i s the approximate ratio of sand to s i l t and clay? What i s the extent of the visible f o s s i l content? Are there any constituents present, such as carbonates, which w i l l present d i f f i c u l t i e s during dispersion preparatory to mechanical analysis? What size sample should be used for mechanical analyses of the sand and the s i l t - c l a y fractions? What number of sieves should be used for sizing the sand fraction? Would i t be practical to size the sample i n a settling tube, such as the Puri Siltometer? How much work and what equipment w i l l be required for mineralogical studies? What time and equipment should be made available for investigations of genera! physical and chemical properties? What i s the best method of sampling the materia! brought to the laboratory? Result of a preliminary binocular examination, together with information on the source of the sediments, the number and size of the samples, and the pur-poses for which laboratory information i s required, w i l l form a basis for setting up laboratory schedules, Plate I, B shows a suitable type of binocular microscope. This i s a Bausch and Lomb instrument giving magnifi-cations of 7, 20 and 40. The binocular microscope also has an important use i n the gathering of mineralogical data. Samples of sized fractions, as obtained from sieving or siltometer runs, can be examined to decide i f the mineral grains require cleaning prior to identification; secondly i f i t would be feasible to do heavy li q u i d , magnetic or superpanner separations; thirdly, as to what proportion of mineralogical work can be done under the binoculars, and of the petrographic microscope work to be done, should examination be made i n thin section, i n index o i l mounts or by staining techniques. When samples have been put through preparation, separation and mounting pro-cedures, the binocular examination can be carried out i n detail to the PLATE I Some Laboratory Equipment For Examination of Recent Sediments A. Tyler Sieves and Rotap. B. Bausch and Lomb Binocular Microscope. G. Hydrometer Tubes, Mixer and Constant Temperature » Immersion Container. D. International Centrifuge, size #1. E. Puri Siltometer. F. Isodynamic Separator. G. Heavy Liquid Separation Apparatus. H. Petrographic Microscope with Attachment for making camera lucida drawings. I. Abbe Refractometer set-up for calibration of index o i l s . - 100 -limits of this instrument. The procedure used i n mineralogical examinations of Bute Inlet samples included work under the binoculars on a l l sand fractions prior to microscope examination. The binoculars were used for grain counts of a l l minerals., except quartz and feldspars, and for selection of representative grains for microscope identification and description. The grains selected were placed i n small cardboard holders made specially for the purpose and set aside for later microscope work. The binoculars afford a means of working out the more obvious minera-logical features and of doing accurate sampling i n preparation for detailed microscope investigation. To assist i n the binocular appraisal, use was also made of ultra v i o l e t examination, each sample being examined for such fluorescent minerals as calcite, f l u o r i t e , hydrozincite, powellite, scheelete, willemite and zircon. The data obtained from the binocular examination of Bute Inlet samples was incorporated with that obtained from petrographic microscope examination and i s shown i n Table X. Separation Procedures During the course of mechanical analyses, the sand fraction can be sized by sieving or by a settling tube technique. Binocular examination of these sized fractions w i l l assist i n deciding what further separation procedures to use. Heavy Liquid Method.- Unless the sample appears to consist almost entirely of quartz or of any other individual mineral, some sort of separation pro-cedure i s of assistance i n describing the mineralogy of unconsolidated sediments. Heavy liquids provide a means of making a separation on the basis of specific gravity. Anyone of a number of heavy liquids may be used, but the most suitable are bromoform, acetylene tetrabromide and methylene - 101 -iodide. Bromoform haa an S.G. of 2.87 and is less viscous than acetylene tetrabromide; acetylene tetrabromide has an S.G. of 2.96 and is less volatile than bromoformj methylene iodide has an S.G. of 3.32 and is parti-cularly suitable for making a separation between micas and other heavy minerals. Bromoform is the cheapest and most widely used liquid for heavy mineral separation. It does not actively corrode the bases in a mineral. If acetone or alcohol is introduced into bromoform, either as a means of lowering specifio gravity for the separation of certain lighter minerals or as a result of the process of washing mineral grains, the pure undiluted bromoform can be recovered by shaking with water and washing out the acetone or alcohol (Ross, 1928, p. 33-4). Numerous heavy mineral techniques are described in the literature and several of these were taken into use during the examination of Bute Inlet sediments. A Fraser tube, as illustrated and described by Krumbein and Pettijohn (1938, p. 339), was made and used for sediments of plus 60 mesh particle size where a qualitative determination was required. The tube was found to be useful for checking the non-magnetic fraction in isodynamic separates for such heavy minerals as zircon. The pear-shaped separatory funnel shown In Plate I, G was found to be satisfactory for fairly large samples of material of at least 150 mesh particle size. However, i t is a very slow means of making a separation, and for material of minus 150 mesh size i t is of l i t t l e practical use. The procedure involves weighing the sample, pouring i t into the heavy liquid in the funnel, and weighing the two fractions following separation, after f i r s t cleaning the mineral grains with acetone and drying them. The separation thus assists in mineral identification as approximate specific gravities are known, and there is a better opportunity of spotting the relatively few heavy minerals after they have been concentrated in this way. - 102 -The most complete descriptions' found of heavy liquid procedures are those of Krumbein and Pettijohn (1938, pp. 319-344) and Twenhofel and Tyler (1941, pp. 67-82). There are many other descriptive articles, a few of which are listed in the bibliography. A very effective method of heavy liquid separation for sediments greater in particle size than 150 mesh is that described and illustrated by Leroy (1951, p. 174). Separation is oarried out in an evaporating dish, using bromoform, and the "lights" are decanted into f i l t e r paper in a glass funnel. This proved to be a much more practical method than the separatory funnel procedure, but again i t was not found suitable for fine-grained sediments.. As much of the Bute Inlet sand fraction is very fine-grained, i t was found necessary to investigate various centrifuge techniques. A procedure described by Natelske (1951) proved to be very satisfactory. It employs 'the common centrifuge technique, but in addition, the bromoform is frozen following centrifugation, thereby preventing mixing of the "heavies" and "lights" during the process of removing the separates from the centrifuge tubes. The method was designed for doing separation work on fine-grained materials and is therefore suitable for marine sediments. The centrifuge used was a 115 volt, 1.5 amp, 0-60 cycles, 132 watts, Clay-Adams "Safeguard Centrifuge" with an 8-inch head and four centrifuge tubes. The procedure, as detailed by Natelske, involves the removal of air bubbles and the mixing of particles prior to centrifuging by the process of vacuum treatment, and for this a -fc H.P. Evacuation Pump, as made by Nelson Vacuum Pump Co., and a& ordinary laboratory desiccator were used. A deep-freeze is also re-quired for freezing the bromoform, following centrifugation. For large scale investigations of fine-grained sediments, i t is suggested that this method be taken into use i f heavy liquid techniques are to be employed. - 103 -Only a few samples of Bute Inlet sediments were separated by thisvmethod, but enough was done to show the superiority of centrifugation over ordinary gravity separation where fine-grained sediments are involved. For many samples, i t would be preferable to use a centrifuge with a head capable of carrying at least eight tubes. It i s also recommended that i n the f i l t e r i n g of heavy liquids, a porous f i l t e r paper, at least Whatman No. 4, be used. Isodynamic Separator.- As an alternative to heavy liquid separation, a method making use of magnetio properties of minerals is worthy of con-sideration In designing a scheme for the examination of unconsolidated sediments. Separation based on magnetic attractability of minerals u t i l i z e s the fact .that minerals respond differently to externally produced el e c t r i c a l effects and the forces produced from these effects. Magnetic separation consists i n introducing a mixture of particles, which respond differently to a magnetic f i e l d , into such a f i e l d under conditions that subject a l l of the particles equally to the f i e l d force and to the force of gravity. The magnetic properties of a mineral are due to a directional alignment of certain of their atoms or atom groups under the influence of an external magnetic f i e l d . These alignment constituents add magnetio effect within the mineral particle to that of the f i e l d , and as a result of-this concen-tration of magnetic effect within the mineral, mechanical forces are set up between i t and the f i e l d . Each mineral species reacts with characteristic strength to the imposed magnetic f i e l d ; this d i f f e r e n t i a l , together with the force of gravity, is made use of i n such machines as the isodynamic separator (see Plate I, F) to achieve a separation of the mineral con-stituents of a sample. In experimenting with the machine, several tests were run. A mixture of ilmenite, garnet, quartz, feldspar, biotite and monazite was passed - 104 -through the machine with a side t i l t of 20° and a forward t i l t of 20° and a current of 0.3 amps. This removed the ilmenite, changing the"side t i l t to 10° and forward t i l t to 15° and current to 0.5 amps, removed the garnet. Alternatively, i f garnet is only present in small amounts, a current of 1.0 amp. holds i t on the magnet t i l l other minerals have flowed through and then the currant can be turned off and the garnet will run through. Quartz and feldspar were separated from the remaining material by using a side t i l t of 15°, a forward t i l t of 20° and a current of 1.2 amps. Biotite and monazite were not separable on this machine but could be separated on the superpanner. This Illustrates the adaptability of the instrument for individual mineral separation. Another separation was made by setting side and forward t i l t s at 20° and making current adjustments to take off several mineral fractions. A mixture of quartz, barite, feldspar, tourmaline, garnet and ilmenite was passed through with the current indicator set at 0.5 amps. This separated garnet and ilmenite from the remainder of the sample. Garnet and ilmenite were separated using a current of 0.25 amps. Quartz, barite and feldspar were separated .from tourmaline under a current of 1.0 amp. For the Bute Inlet samples, one setting was used to achieve a separation between the strongly magnetic and the weakly-or non-magnetic minerals. The setting used in the size range minus 35 to plus 200 mesh was side t i l t of 30 ° , forward t i l t of 25° and a current of 0.75 amps. For the finest fraction, the current was boosted to 1,0 amp. With such settings a separation was made between the principal minerals quartz and feldspar - the non-magnetic fraction, and amphiboie and micas - the magnetic fraction. The majority of the accessory minerals occurring in the Bute Inlet samples appeared in the non-magnetic fraction with quartz and feldspar. - 105 -In this investigation, a l l sand samples were put through the isodynamic separator after sizing by the sieve method. As there are very few, i f any, light magnetic minerals, i t was.only necessary to use heavy liquid procedures on the non-magnetic fraction, during which such minerals as zircon and sphene were recovered from this quartz-feldspar fraction. Thus by sieving, and then doing magnetic and gravity separations on each size fraction, the project of assembling mineralogical data on unconsoli-dated sediments by microscoping means was made easier. The isodynamic separator receives l i t t l e , i f any, mention in sedimentary petrology books and journals, but i t was found to be very suitable for the work in hand and is recommended for further investigation. It finds a wide use in the investigation of metallics. Two precautions are necessary: only carefully-sized material should be put through as a sample} and failure to remove a l l magnetite with a small magnet before putting a sample through wil l require that the machine be partially taken apart and the brushes cleaned by hand. Goldich (1938, p. 19) describes a separation method combining heavy liquid and magnetic techniques, but only, an ordinary electromagnet is used. Infrasizer.- The Haultain Infrasizer is an air elutriator and although i t was developed especially to meet the sub-sieve sizing requirements of ore dressing laboratories, i t is suggested as a suitable means of making mechanical analyses of certain sediments and of obtaining sized fractions for mineralogical study. It could be used in conjunction with sieving for mechanical analysis work and the various fractions obtained used for mineralogical study. It would have no place in the mechanical analysis of recent marine sediments as these materials should not be dried before analysis of the minus 250 mesh portion, but i t would be an excellent method of sizing terrestrial deposits such as river s i l t s or loess. It might also be employed for sizing silt-clay fractions after hydrometer or pipette - 106 > tests had been made. This would give a fraction in each of the seven tubes and as the final split i s usually made at 10 microns, the products in the tubes would represent practically a l l of the s i l t , and the material of less than 10 micron diameter going over into the collecting bag would be pre-dominantly of clay-size material. The s i l t fractions could then be studied spectrochemically to see i f such elements as manganese or strontium have a significant size distribution, and the minus 10 material would be available for clay mineral identification. The infrasizer uses samples of 50 to 800 grams. The diameter of the tubes varies as the square root of 2; therefore the average diameter of succeeding products varies also as the square r6ot of 2, as in the Tyler screen series. It is preferable to run at least a 100 gram sample, which takes about 1§- hours; consequently i t might be necessary to combine two or three hydrometer residues or make up a special sample. Haultain (1937) gives details on the technique of operating the infrasizer. ' Superpanner.- The Haultain Superpanner is a mechanical panning tabling device developed for testing by making precise gravity separations of small samples of fine material. It performs efficiently on closely sized fractions between the range of 65 mesh and 14. microns and handles a:10 to 15 gram sample. The wide range of adjustments - slope, intensity of end bump, length of stroke, number of strokes per minute, amplitude of side shake, number of oscillations per minute, amount of water and depth of pool in the down-slope end of the pan - make this a very flexible machine. It is not suggested that i t be used in conjunction with the infrasizer, as is done in ore analysis, but rather that i t be used as a means of separation for sands that consist of two principle constituents which although differing in shape and specific gravity do not respond to a magnetic method of separation. This use was demonstrated in a sample by separating biotite - 107 -from monazite after other minerals had been removed by the isodynamic separator. It was also used on some of the Bute Inlet samples as a pre-liminary examination procedure: the silt-clay was of course drawn off but l i -the table provided a quick means of spreading out ei 15 gram sample as taken direct from the container and of estimating visually the sand: silt-clay ratio, as well as the general nature of the mineral assemblage. Haultain (1937) describes the customary use of the table in making mineral separations in ores. No reference was found, in the books and publications examined during the course of this investigation, referring specifically to the use of the isodynamic separator, infrasizer or superpanner in sedimentary pet-rological researoh workj but i t would seem that these Instruments might well be employed in some phases of such work, especially where large numbers of samples are to be handled. Microsplitter.- The laboratory study of unconsolidated sediments calls for three stages of sampling: the selection of representative material in the field; the reduction of the sample taken to the laboratory to a suitable size for mechanical analyses, which in turn provides sized fractions for mineralogical study; and thirdly, the accurate sampling of these sized fractions for the purpose of obtaining amounts sufficiently small for pet-rographic examination. In this third phase of sampling, i f the silt-clay fraction is being prepared for clay-mineral study, the centrifuge affords the best means of getting suitable samples. If samples for mounts of sand-size sediments are required, the microsplitter is a reliable tool. Regard-less of the stage of sampling, final results depend in i t i a l l y for their accuracy on the success of the sampling procedure. Consequently, the matter of sampling demands careful attention in any laboratory investigation. The Otto microsplitter (Otto, 1933, pp. 30-39) is commonly used for - 108 -splitting a samd sample down to convenient size for mounting. It is made on the same plan as the Jones ore sampler, but is minature in size and care-fully machined. A splitter, similar to the Otto model, was made for this investigation, from plans given in Engineering and Mining Journal (1937, pp. 185-186), and i t was used in sampling of sieved sand fractions in order to get representative portions for mounting and also to obtain suitable amounts for grain counting in mineral frequency analysis. Some statistical aspects relating to sample splitting are discussed by Otto (1937, pp. 110-133). An alternative to the microsplitter is the customary method of coning and quartering. However, this may give rise to large errors when small samples are being split. Several varieties of rotary type and oscillatory-sample splitters are also described in the literature. The Spectrographs Laboratory, Mines Branch, Department of Mines and Technical Surveys, Ottawa makes use of a specially designed shaker to ensure uniform distri-bution of mineral grains in a sample before passing the sample through a microsplitter. Preparation and Mounting A binocular examination will determine what mineral grains should be mounted and what type of mounting should be used and also what other pre-paratory measures, such as clarification of grains and staining, should be undertaken. Mineral grains of the Bute Inlet samples did not require a cleaning process, but in order to investigate this laboratory procedure, work was done on some soil samples. The samples had f i r s t been dispersed and the sand fraction removed by wet sieving. The mineral grains so recovered were masked by a black stain, making identification impossible. Satisfactory - 109 -methods of removing iron oxides from mineral grains include the hydrogen sulphide method of Drosdoff and Truvey (1935, pp. 669-673) and the acid potassium sulphate fusion method of Mackie (1918, pp. 119-127). Gilbert (1947, pp. 83-85) discusses and compares phosphoric acid, tataric aoid and ci t r i c acid methods. The procedure used on the samples worked on in this project was that described by Marshall and Jeffries (1946) and by Leith (1950, pp. 114-116) which consisted of making up a solution of 50 c.c. of distilled water, 2 ml. 50% sodium hydroxide and 10 gms. of oxalic acid. A hollow aluminum cylinder, 2jtn x 2 H x 3/32" was added to this solution and then the sample poured into the solution and the whole boiled gently for 20 minutes. This aluminum oxalic acid method was found to be effective and is easily carried out. It removes deleterious material, yet does not adversely affect the mineral grains. Some grain clarification is essential for coated grains prior to further preparation and mineralogical examination. It is particularly necessary where a staining technique is to be used as an aid to mineral identification. Staining was found to be an effective way of quickly distinguishing between quarts and feldspar particles of the Bute Inlet sediments. The following technique was used in preparing the grains. A representative sample of about 500 grains was obtained from each screen size of the sand fraction by using the microsplitter. This sample was added to a small porcelain cup containing a few c.c. of hydrofluoric acid. At the end of a minute, the acid was decanted off and the grains washed several times with distilled ^ater. Then a few c.c. of malachite solution were poured into the porcelain cup and the grains allowed to soak in this solution for 10 minutes. The malaohite solution was then decanted off, the grains washed and spread out on a slide for examination under the microscope. As the - 110 -quartz grains remained unstained, they were readily distinguished from feld-spar grains. Other staining techniques for making distinctions among various members of the feldspar group are described by Leroy (1951, pp. 196). However, these were not found to be very satisfactory for the sediments being examined and were abandoned in favor of an index o i l method. The only other staining techniques used in this project are those described by Leroy (1951, pp. 197-199) for identifying clay-mineral groups. For this work, malachite green and methyl violet solutions were made up by . dissolving 0.1 gms. of the crystals in 25 c.c. of CP. nitrobenzene solution; a nitro-benzene solution saturated with safranine Y was prepared; and a fourth solution, benzidine in water was also prepared, but difficulty was experienced in getting the benzidine into solution. These solutions, which were prepared under the direction of Dr. R. E. Delavault, University of British Columbia Geological Laboratories, were tried on kaolinite, montmorillonite and i l l i t e standards and were found, with the exception of the benzidine, to give the color results described by Leroy. McConnell (1947, pp. 6-8) also describes the clay tests and states that a saturated water solution of benzidine produces a blue coloration in contact with clay minerals of the montmorillonite group. These solutions, although giving definite results on the pure clay standards, produced no results when the Bute Inlet samples were tested, possibly due to the very low clay-mineral content of these sediments. In using these solutions to assist in clay-mineral identification, the following technique is suggested: disperse the sample, recover the minus two micron fraction either by centrifugation or by decantation and gravity settling, apply a drop of solution and examine under the microscope using bright reflected and transmitted light. This is not a field method and even under good laboratory conditions may give doubtful results, except - I l l -for the relatively rare deposits which are very high in clay minerals. To be of any use, the method would have to be supported by X-ray and diffe-rential thermal analysis check work, but i t might be used as a rapid means of testing a great many, samples in connection with a differential thermal analysis and X-ray program and therefore would be of use in oceanographic and soil survey projects. It would seem, however, that the method by itself has very l i t t l e value. Mineral grains may be studied under the microscope by merely placing them on a glass slide or by mounting them in an index o i l , in which cases no preliminary preparation other than grain clarification is required. Thin sections offer a means of mineralogical identification in the study of unconsolidated sediments, and while i t is not feasible to make up large numbers of them because of the time factor involved, they are of con-siderable help in the study of fractions where many mineral species are present. Under the direction of Mr. J. A . Donnan, University of British Columbia Geological Laboratories, the following method was used in pre-paring thin sections of sand grains. A few drops of Canada balsam in xylol were poured on to a cover glass which had been placed on a hot plate. When the balsam mixture became thin, 200 to 300 send grains were dropped into i t , the mixture cooked for a minute and then the cover glass removed from the hot plate. The exposed side was ground flat and polished for mounting. The cover glass was placed, with the ground side down, on a petrographic mounting slide containing an even thin layer of cooked balsam. The slide was immediately removed from the hot plate and the cover glass pressed on t i l l the balsam hardened. Next, the cover glass was ground off and grinding continued t i l l the re-quired 0.03 mm. thickness was reached. A cover glass was then placed over the ground surface in the customary manner. Plate II, A is a photomioro-- 112 -graph of a thin section made from a Bute Inlet sample. Leroy (1951, p. 178) describes a similar procedure, but starts with a slide and removes i t after the f i r s t grinding step has been completed. Either method gives good results, but i t requires considerable practice to be able to complete a mounting in 25 to 30 minutes. A thin-section mount of individual grains gives no idea of the spatial relationship of the constituents of a sample. Consequently a method was needed which would provide a thin section preserving spatial d i s t r i -bution of grains in the same way that a rock thin section does, thus giving some idea of texture. A method, used in soils work by R. W. Chauncey of the University of British Columbia agronomy Department, was tried and found to be of considerable promise. The following steps were taken in preparing this type of thin section. A sliver about 1" x 1° x was carefully cut from the sample, placed in the air t i l l dry thereby attaining a certain degree of cohension so that i t could be handled and then placed in a large test tube and bakelite (#T1845 - a varnish-like liquid) added. The test tube was set in a desiccator, a suction pump attached, and air evacuated down to 30 inches. The valve was closed, and the test tube allowed to stand in the desiccator over-night. The sample was then placed in an oven; the oven was heated and held to a temperature of 80° for two hours; then the temperature was increased to 130°C slowly and held for at least five hours. The hardened pellet, which had been impregnated and baked in bakelite, was mounted lightly on a slide using Canada balsam and was polished with fine emery paper and with aloxide polishing powder. The pellet was next removed from the slide, turned over and stuck firmly with Canada balsam, and the polishing continued with aloxide down to 0.03 mm., using the petrographic microscope to check the thickness. A cover glass was placed over the pre-- 113 -pared section and the procedure was complete. The section so obtained provides a means of studying textural and structural features as well as some mineralogy. Plate II, B is a photomicrograph of a thin section pre-pared by this bakelite method. The thin section was made from core number 22 of the Bute Inlet sediments. Plate II, C is a bakelite thin section of a soil sample showing a prominent structural feature, and Plate III, D illustrates the possibilities of mineral grain study in such mounts. The preservation of wet fragile specimens has an important appli-cation in the study of recent marine sediments, and the most suitable method found is that described by Arthur (1949, pp. 131-134). The, procedure calls for dipping specimens in. a syrup made of a plexiglass compression molding powder with ethyl methacrylate and methyl methacrylate monomers. Another way of treating freshly collected wet sediments is Bucher's method (1938, pp. 726-755). The fresh sample is placed in a copper box and suspended by means of a sieve in a diethylenedioxide solution about three cm. above a layer of calcium chloride, which removes any water from the solution. The dioxane impregnated sample is then placed in melted paraffin and the temperature slowly raised- to 105°C until the paraffin has completely replaced the dioxane which evaporates. The treatment requires three to five days, but is suggested as an excellent way of preserving unconsolidated sediments without loss of moisture. Unconsolidated sediments may also be kept in their natural state merely by sealing in paraffin as soon as the sample is taken in the field. Any such precautions as these w i l l help to keep the clay mineral content in the same form in whioh i t occurs in the source bed. In examining index o i l mounts, i t was found that considerable time could be saved and more representative results obtained i f some means could be devised for holding grains to the slide while an index o i l was - 114 -being washed off i n preparation for addition of another o i l to the same grains. Canada balsam was tried but i t i s not very satisfactory for mounts of grains finer than plus 100 mesh because i t i s d i f f i c u l t to avoid covering up the grains during the mounting procedure. What apperas to be an ex-cellent technique is that described by Fairbairn (1943, pp. 396-397) who recommends use of gelant5.n-coated slides. These slides, available from the Will Corporation, Rochester, N. Y., are 25 x 44 mm. A drop of water i s applied to the area where grains are to be placed and then i t i s shaken off after a few seconds and the grains immediately scattered over the softened gelatin. The embedded grains are capped with a cover glass and the usual procedure for repractive index o i l immersion carried out. After examination with one o i l , the grains may be studied i n other oils merely by washing off the used o i l with carbon tetrachloride. Becke line or oblique illumination tests can be carried out i n grains so mounted, according to the author, because the gelatin coating i s much thinner than the diameter of the smallest grains l i k e l y to be used. Piperine i s mentioned as a possible mounting medium as i t s index of refraction i s 1.68 and i t therefore provides a means of studying grains of higher refractive index more effectively than can be done i n Canada balsam. A method used to transfer a grain from one index o i l to another was used i n several instances. For the purpose ai'small holder was made by fusing a thin wire into a drawn out glass rod by means of Canada balsam. The grain was removed from one o i l on the end of the wire and washed i n xylol before being plaoed i n another index o i l . In the course of studying Bute Inlet samples the following methods were used i n preparing for microfossil study. Sponge material was of sufficient size a s to be easily picked out of the sample under the binocu-lars and examined microscopically. Foraminifera, diatoms and calcareous - 115 -algae were recovered by plaoing a sample of the sediments, as taken from a core or bottom sample, in a inch porcelain evaporating dish, adding carbon tetrachloride and swirling the sediments in the dish for a few minutes. The microfossils came to the top of the liquid and were then de-canted off into another dish. The carbon tetrachloride can be filtered off and re-used. Water can be used as an alternative, but carbon tetrachloride is more effective. Individual specimens were also recovered during binocu-lar examination by using a camel's hair brush. Several other methods are described by Aushman (1948, pp. 1-10). Mann (1922, pp. 1-8) suggests placing diatoms that have been re-covered from sediments in a solution of 35$ alcohol. When ready for study, a strewing is made by stirring the alcohol, drawing off a drop and placing i t on a slide. The alcohol-water mixture can then be evaporated and the diatoms have good distribution on the slide. Mineral Identification Procedures After the sized sand fractions, as obtained by sieving or the use of a settling tube, have been separated into magnetic and non-magnetic portions, and the non-magnetic fraction further divided by heavy liquid procedure, mineralogical examination can be started and any of the mounting techniques described above used to assist in making observations under the microscope. The "light" minerals of the non-magnetic fraction of the Bute Inlet sample were found to be chiefly quartz and feldspar. The problem therefore was to get as accurate an estimate as possible of the proportion of quartz to feldspar in each sample and also a breakdown of the feldspars into several main components. The quartz: feldspar ratio was determined by - 116 -staining the grains with malachite green, as described in the section on preparation and mounting, and making grain counts on samples consisting of about 500 grains. Feldspars present a difficult problem in the study of unconsolidated sediments and many investigations merely report them under the group name. It is obviously impossible to draw any conclusion from a few determinations, such as might be made using the universal or flat stages and getting values of extinction angles in zones perpendicular to Z or to 010. One value of An. 20 might be obtained, another of An. 60, but there would be no way of knowing the composition distribution unless a great many determinations were made. The determination of any optical property or any physical pro-perty for a large number of grains presents the same problem: lack of reliability unless a great many measurements are made and the impossibility, because of the time factor, of making numerous measurements on individual grains. Furthermore, l i t t l e i s to be gained from results of precise iden-tification within the feldspar group, but i t is of value to know whether the average composition of the plagioclases is towards the sodio end or the calcic end, and just what the proportion of K-feldspars to plagioclase i s . The following procedures in dealing with feldspars were therefore adopted. The selection of two sub-groups within the plagioclases was based on this reasoning. A grain of feldspar showing an index of refraction greater than a liquid of index 1.552 cannot have a value of An. less than about 30. If a l l indices of refraction are greater than the liquid (1.552) i t is hardly likely that the grain w i l l have a value less than about An. AA> If the indices of a grain of the plagioclase are less than 1.552 the com-position is hardly likely to be greater than about An. 30. If one index is less than the liquid and one greater, then the general composition must be between An. 30 and An. AA> As small grains of feldspar consist in large THE UNIVERSITY OF TORONTO PRESS - 117 -part of 001 and 010 cleavage plates, the indices in these plates are diagnostic and the assumption was therefore made that any grain showing indices on both faces greater than 1.552 had a composition of at least An. 44. This was the basis for making a mass determination of the nature of the plagioclase content. It was also assumed that for a number of grains of quartz and felds-par, a l l those having both indices less than 1.53 could be considered to be K-feldspar. Thus for such an aggregation, the quartz content was determined by stainingj the K-feldspar by immersing in a mineral o i l of index 1.53; and that part of the plagioclase greater than An. 44 by immersion in an o i l of index 1.552. The proportion of plagioclase less than An. 44 was com-puted by subtraction of quartz, K-feldspar and the plus An. 44 plagioclase from the total grain count. For the typical non-magnetic fraction of the Bute samples, which was 99% quartz and feldspar, this method seemed to be a reasonably accurate way of making a general appraisal of the main sub-species. It was checked against detail work done on several thin sections and found to be a workable method. Data obtained by these methods are incorporated in Table X. Examination of feldspars points to a major problem in mass identifi-cation work on unconsolidated sediments. There are so many variables that even though a method might appear reliable, there is no means of positively establishing it s reliability. The bases of sedimentary studies is statistical, and consequently there is only one way of approaching accuracy and that is by making as many measurements as the scope of the project w i l l permit. The use of index oils seems to offer the best approach to mineralo-gical identification when dealing with unconsolidated sediments. In this - 118 -project, the Abbe Refractometer was used to calibrate immersion oils at three different temperatures and for three different wave lengths - red, yellow and blue light. The Abbe Refractometer consists essentially of four parts: the telescope, Abbe prism, the sector, and the compensator prisms. The instrument is illustrated by Rogers and Kerr (19-42, p. 49). A water heater is connected to keep the temperature of the refractometer and of the mineral o i l constant. Water circulates from the heater through tubes to the instrument in a closed circuit thus insuring uniform temperature throughout the system. Graduations permit direct reading of the index to the third decimal. Figure 8 shows some curves obtained from calibration of the immersion oils. These curves were worked out in collaboration with J. A. Gower and B. D. Prusti under the direotion of Dr. K. C. McTaggart of the University of British Columbia. Figure 9 is a correction curve for the Bausch and Lomb Abbe Refractometer with explanatory tables included. Table XI shows some readings taken during calibration of oils No. 13 to No. 19 and the indices of refraction for temperatures 14.8° and 20°C at various wave lengths. Once the oils are calibrated, the petrographic microscope is set in front of a monochromatic light source and the grains are examined in a selected mineral o i l . Both inclined illumination and Becke line methods of comparing indices of o i l and mineral grains can be employed. Plate 1, I shows the Abbe Refractometer, light source and water heater. In investigating the plagioclase content of a sample by using an index o i l of 1.552, Figure 8 shows that o i l No. 18 at 14.8°C and a light of wave length 540 lambda would give the required index. Alternately, an unknown mineral grain can be placed in an o i l of known index and the wave length changed until the grain becomes invisible j then the index of re-fraction can be read from the graph by referring to the ordinate figures. CORRECTION CURVE FOR BAU5 'CH &, L O M E F i & U R E S A B B E R E F R A C T O M E T E R a. 3 R ^5 CORRECTION NQ 130 /.35 1.40 1.AS 1. So 1 55 160 /.65 1.70 03bS 0011 0007 O O O f 0 001 0001 O O O i 0 0 O 3 0011 ons 0008 0 00 J OO 03 O O O Z 0 0 0 1 OOOI o o o l 0009 47^ 0 Z O 3 0001 O O O i r - O O O i O O O I 0 0 0 2 . 0006 Soo OI44- OCXS 4- 0003 O O O I 000/ OOOI 0003 S7S 0 0 9 5 OOOI 0 0 0 J O O O i 0003 5 So O05"3 O o o j OO Ol 0000 0 0 0 2 . 575 OOI s 6O0 0014. - O O O i - 0 0 0 1 6Z.5" 0 0 4 0 -ODOZ OOOI - O O O I 'OOOI 6 5 0 0 0 6 4 - -cool, -OOOI - O O O I -OOOI - O o o z 675" -OOOi -Oooz, - 0001 - c o o i - 0 0 Ol -oooz Too otoS -OOo3 - O O O i . - O O O I . — O O O I • o o o z ^ 003 Nf-lnoei or DESiReo Wave LEH&TH O3<o Y O37o T - 119 -TABLE XI Compilation of Index O i l Data:Indices of Refraction Temperature of 20°C. Temperature of 14.8°C. O i l No. 476 mpk 589 mm. 700 mm. 476 mm 589 m* 700 m». 13 1.5085 1.5163 1.5208 1.5113 1.5198 1.5230 .0200 1.5285 -.0105 1.5103 .0200 1.5313 -.0105 1.5125 14 1.5136 1.5214 1.52a 1.5151 1.5239 1.5264 .0200 1.5336 -.0105 1.5136 .0200 1.5351 - .0105 1.5159 15 1.5180 1.5258 1.5290 1.5201 1.5277 1.5307 .0200 1.5380 -.0105 1.5185 .0200 1.5401 -t0105 1.5202 16 1.5264 1.5330 1.5351 1.5293 1.5364 1.5391 .0200 1.5464--.0105 1.5246 .0200 1.5493 - .0105 1.5286 17 1.5289 1.5350 1.5375 1.5303 1.5372 1.5395 .0200 1.5489 -.0105 1.5270 .0200 1.5503 -tOlOJ 1.5290 18 1.5395 1.5452 1.5472 1.5420 1.5465 1.5482 • .0200 1.5595 -.0105 1.5362 .0200 1.5620 .0105 1.5377 19 1.5530 1.5562 1.5587 1.5558 1.5592 1.5610 .0200 1.5730 -.0105 1.5482 .0200 1.5758 ,0105 1.5505 It i s usually possible to determine an unknown i n this way after t r i a l with two or three oils.. In most of the Bute Inlet samples, the quartz-feldspar fraction, that i s the non-magnetic fraction, contained very minor amounts of other minerals. - 120 -A heavy liquid separation was made and the "heavies" placed in immersion oils to help establish identification. Such other optical and physical properties as were required for identification were obtained by microscope examination. A l l data concerning heavy minerals are incorporated in Table X. The minerals in the magnetic fraction were examined in several ways. Large grains were observed under the binoculars and representative specimens selected for index determination or for further examination under the micro-scope. Thin sections were made from representative samples of several fractions which appeared to contain a variety of mineral species. Some further separation work was tried on the isodynamic separator but i t \ms found that for Bute Inlet samples, in which biotite and amphiboie are the predominant magnetic minerals, l i t t l e was to be gained by attempting secondary separations and that once the i n i t i a l separation had been made between the quartz-feldspar and biotite-hornblende fractions, the latter group was best investigated directly by microscopic means. Consequently the greater part of the magnetic mineral group investigation was done by placing a sample consisting of several hundred grains on a glass slide and examining the grains under the microscope with bright reflected and trans-mitted lights. Plate I, H shows a suitable microscope set-up. Descriptions of mineral species were made and specimens selected, where necessary, for investigation in index oils. Final identification was made on the basis of color, pleochroism, refringence, birefringence, extinction angle, shape and crystal form, interference figure data, inclusions and alteration. Some of this information, of course, was only obtained when a thin section was made. Once detailed work on the several mineral species had been done, simple criteria were set up for each mineral so that identification could be made at sight or by one or two microscope tests. As most samples were sized by screening before mineralogical - 121 -examination, there was no need to take measurements with a micrometer eye-piece, although such measurements were made on grains singled out for detailed microscopic examination and on samples not previously sieved. Considerable emphasis was placed on color as a means of singling out grains and as a f i r s t step in identification. In the mineral identification procedure, a table compiled for the determination of detrital minerals was found to be of considerable value as minerals were grouped by colors, and the optical and general data included assisted further in tracking down a mineral in a systematic manner. Table XVII was compiled from information in sedimentary petrology texts and was used as a guide in mineralogical work. No investigation of surface texture was done on Bute Inlet samples as these sediments are too fine-grained. However, details of grain surface, independent of size, shape or mineral composition could be of considerable diagnostic value in studying some types of unconsolidated sediments. Williams (1937, pp. 114-128) gives some criteria which could be of help in dealing with surface texture. More important for the purposes of this study than descriptions of surface details was an appraisal of the degree of weathering which the mineral particles had undergone prior to deposition. Dryden and Dryden (1946, PP« 91-96) present a scale of comparative weathering rates which is an aid in studying weather effects. Similar data is also given by Pettijohn in a comparison of persistence of heavy minerals and geologic age (1941, pp. 610-625). Mineral Frequencies Grain counts were made of each grade size as soon as the mineralogy was worked out. It was found best to make counts with the microscope using low power and strong light to show up the color differences which assisted - 122 -i n spotting the minor minerals. The percentage mineral composition of a sample was arrived at i n the following manner: size grade fractions, as achieved by sieving were weighed; magnetic and non-magnetic fractions of eaoh size grade were also weighed; mineral grain counts were carried out on the magnetic and non-magnetic fractions and frequency expressed i n per-centages. Approximately 300 grains were counted i n the two fractions of each size grade. Accuracy of the percentage figures obtained is not only dependent on correctness of mineral identification but also on adequacy of the sampling procedure. Dryden (1931, pp. 233-238) has analysed the probable error involved i n grain counting. From his data, a count of 300 would have a probable error of 17$ for minerals making up 5$ of the sample and 2$ for minerals making up 80$. A count of 300 was therefore thought to be adequate and within the range of sampling errors. Furthermore, even by counting 700 grains, the probable error i n the 5$ bracket would only be lowered to 11$. Allen (1945, pp. 173-174) points to the large errors to which laboratory examination of fine-grained sediments are susceptible and the accuracy which may be expected. In addition to errors involved i n working per-centages out from grain counts, another source of error l i e s i n combining weight and number percentages. Weight percentages could be computed from count data i f allowance were made for specific gravity differences, pro-vided that there was uniformity i n grain dimensions i n a given size fraction. As such uniformity does not exist and as i t is not feasible to weigh small amounts of various mineral species, the weight-count method possibly gives as accurate a result as can be obtained i n the examination of a large number of samples. Mineral frequency data for the Bute Inlet samples has been compiled and i s shown graphically i n Figure 1, A. Such data have use as descriptive - 123 -measures but their main value would be apparent i n a comparison of similar data for the source rocks. A comparison thus made would permit a study of the distribution effects of transportation agencies. Figure IA, IB and 1G represent an attempt to relate mineral composition and mineral frequencies of Bute Inlet sediments to the small amount of data on shore-line and inland geology that are available. If detailed land geology and more bottom sample data were available, a basis would be established for studies of the factor of transportation i n the process of sedimentation by the methods indicated herein. Mineralogy of Bute Inlet Sediments The Bute Inlet samples are described i n terms of texture and mineral composition. The results of size analysis are shown i n Figure 1, A. The data on the relation between mineral frequencies and particle sizes for the chief minerals of 20 samples given i n this figure should be examined i n conjunction with sieve analyses of the sand fractions for corresponding samples as given i n Figure 1, B and also compared with the histograms of the same samples as shown i n Figure 1, C. A comparison of the data i n these three figures shows how much sand occurs i n each sample (Figure 1, C), what i s the size distribution within the sand fraction (Figure 1, B), and the relative percentages of each mineral, i n the sand fraction, i n terms of particle size for each sample (Figure 1, A). Figure 1 shows the sample locations i n Bute Inlet together with the depth of water and the median diameter of each sample. Shore-line geology, as known to date, i s sketched in on this map also. An examination of Figure 1, C shows that the sand fractions of a l l samples, except numbers 23, 22, 16, 14, 12, and 2 are not only very small i n amount, but also i n particle size. This fact i s also revealed by the - 124 -cumulative curves of Figure 6. Consequently detailed petrographic examination of Bute Inlet samples by the petrographic microscope must be confined to a very small portion of the total sample and such work does not assume the same importance as i t would i n the examination of unconsolidated sediments which are largely i n the sand-size range. However, certain con-clusions regarding the mineralogy of Bute Inlet sediments are indicated from the data as presented i n Figure 1, A. These conclusions may be summarized as follows. A l l samples are composed principally of five minerals: quartz, K-feldspar, plagioclase, mica and amphiboie. Plagioclases of composition more sodio than An. 44 ere much in excess of those i n the composition range more calcic than An. 44, and sodic plagioclases greatly exceed the total of K-feldspar and calcic plagioclases. Mica i s almost entirely biotite. Of the amphiboles, crystals for which optical properties were obtained i n detail were a l l found to be hornblende but very minor, amounts of tremolite and glaucophane are in d i -cated. Small granitic pebbles are to be found i n the coarsest fractions of some of the samples, as shown i n Figure 1, A. Carbonates do not exceed 0.5$ except i n sample number 2 and consequently only show on the graph for this sample. Each sample contains i n minor amounts one or more of the following: pyroxene, sphene, zircon, muscovite, apatite, magnetite, garnet, and minute amounts of secondary alteration products identified as chlorite, epidote and kaolin. The accessory and secondary minerals are generally present i n total amounts of less than 1$ and are not entered i n Figure 1, A, but are described i n Table X. Furthermore, the data on Figure 1, A also indicate certain con-clusions regarding mineral particle sizes. Quartz occurs throughout the entire size range, but generally reaches a maximum, as a percentage of the sample, at a particle size of about 0.15 mm. K-feldspar, sodic and calcic - 125 -plagioclases, while extending i n most samples throughout the entire size-range, tend to decrease i n relative amount from the finest size class to the coarsest, i.e. from a particle size of about 0.1 mm. to 0.5 mm. On the other hand, biotite occurs i n greatest amounts i n the size range approaching 1 mm. and decreases i n percentage i n the finer fractions. Amphiboie, l i k e the feldspars, i s most common i n the finer fractions. The accessory-minerals also are mostly a l l concentrated i n these finer-grained fractions. With reference to the mineralogy of each sample, as outlined i n Table X, certain general mineralogical c r i t e r i a can be set down as applying to most samples, Quartz. Shape and roundness are dealt with i n a later section, but quartz partioles are generally relatively angular. Ko distinctive i n -clusions were noted. K-Peldspar. The group includes monoclinic and pseudomnoclinic feldspars. No distinction i s made within the group, although very small percentages of the total feldspar oontent with indices less than 1.53 were found to have the quadrille structure characteristic of microcline. Of the few examinations made of K-feldspars i n thin section, none revealed the small optic angle of sanidine. The K-feldspars are very l i t t l e altered, slight alteration to kaolin being noted i n a minority of grains. The particles have retained, i n many instances, their monoclinic form, but generally occur as irregularily-shaped grains flattened parallel to 001 cleavage. Plagioclase. Measurements made i n index oil s separated members of this group into two subgroups at composition An. 44- From the few identi-fications made in thin section, an average composition of about An. 36 i s indicated. Some of the plagioclase crystals are completely unaltered; others are part i a l l y altered to sericite or kaolinite. Some zoning i s - 126 -evident. On a few of the more calcic crystals of larger size, minor amounts of epidote, calcite and zoisite alteration can be seen. The plagioclase grains are irregular in shape and basal in form. As a class, they can be described as being slightly altered. Biotite. Biotite occurs as cleavage flakes varying in shape from hexagonal to rounded irregular. Some flakes are of a uniform brown color with no surface markings except for zircon or other inclusions, but the majority of the flakes are altered in some respect. This alteration takes several forms: the brown color is changed to a golden yellow with a submetallic luster but strong pleochroism is retained; a greenish color, which appears to be contributed by interlaminated grains of chlorite, may be present and with i t small grains of secondary magnetite; a third type of change is also in the form of an olive-green alteration, which appears to start on the outside margin of a oleavage flake and extend towards the center, replacing the original brown color, but with l i t t l e change in bire-fringence. The f i r s t type of alteration described would appear to be due to ordinary weathering; the second, common alteration of biotite to chlorite; the third type may be an i n i t i a l stage of glauconization. Systematic search was made for grains or pellets of glauconite on the basis of its typical shape and color, but none was found. However, as detailed mineralogical examination in this project was confined to bottom samples and to top sections of cores, i t may be that further examinations of sedi-ments near the bottom of some of the longer cores would reveal some definite evidence of the formation of glauconite from biotite. Considering the rather high rate of sedimentation, i t is possible that a much longer core than the 2-4-inch cores recovered to date would be required before any definite results could be achieved in the study of glauconization. - 127 -Amphiboie. Much of.the amphiboie i s common green hornblende i n the form of elongate prismatic grains with pleochroism ranging from pale yellow green to dark green, positive identification being made i n thin section by finding the angle between Z and C i n an optic normal figure. A small per-centage of amphiboie crystals are a pale yellow green and have sli g h t l y lower indices than those of the prevailing hornblende type. These could not be mounted i n sufficient numbers In thin section to determine optical properties, but the color contrast from the predominant hornblende type plus the fact that these particular crystals were noted i n samples 14., 16 and 17 whioh are i n close proximity to^etamorphic rocks on land suggest the possibility of tremolite as a second representative of the amphiboie group in Bute Inlet sediments. X-ray diffraction studies of any minor represen-tatives of this group would be required before identification could be assured as the d i f f i c u l t i e s of getting sufficient.numbers of relatively rare components onto a thin section mount to give at least one suitable orientation for optic normal observation are quite considerable, the d i f f i -culties being increased due to the minuteness of the grains. A soda-rich amphiboie, possibly glaucophane, was noted i n one sample. Except for slight rounding of edges, a l l amphiboie grains have retained their prismatic form. Alteration to chlorite i s minor. Plate II, F shows amphiboie grains of sample 16. These minerals - plagioclase, biotite, quartz, orthoclase and amphiboie - constitute well over 90$ of the Bute Inlet sediments, in the sand fraction. The following minerals are also to be found i n most samples. Pyroxene. Occurring only i n very minor amounts, pyroxene i s i n the form of monoclinic crystals with generally a pale greenish-brown color. Positive Identification within the monoclinic group was not made, although the colors and indices of refraction correspond to those of augite. - 128 -Prismatic form is retained; greenish alteration i s apparent. Zircon. Found i n most samples, this mineral is usually i n the form of tiny elongate pale yellow prisms with pyramid terminations. It also occurs as inclusions i n biotite. Sphene. This mineral occurs as irregular grains or small diamond-shaped crystals and was noted i n several samples. The brownish yellow color, shape and high refringence serve as identifying markers. Muscovite. Some samples containing abundant biotite also have oolorless rounded cleavage flakes of muscovite distinguished by their grain shape and transparency, and identified by interference figures and the position of the optic plane. Compared with biotite, muscovite i s rare. Apatite. Minute irregular grains, rounded or hexagonal crystals of apatite are found i n most samples. Size, form, and color aid i n i d e n t i f i -cation. The six-sided form is rare, the grains generally being e l l i p s o i d a l . Epidote. Epidote i s relatively abundant i n a few samples. The greenish yellow color and sub-angular equidimenslonal form make these grains distinctive. They are also much larger than zircon, sphene or apatite. In thin section, the strong birefringence and high refringence serve as con-firmatory properties. Garnet. Colorless, pink and brown garnets were noted i n many samples. Isotropism, high r e l i e f , conchoidal fracture and irregular form characterize this mineral. Minute inclusions were seen i n a few crystals. As X-ray work was not done on the garnets, positive identification within the garnet group was not made. However, c r i t e r i a of color, high indices of refraction and slight birefringence would seem to place the specimens observed i n the ugrandite group, possibly mainly grossularite with some andradite. No alteration was seen. Like epidote, and i n contrast to zircon, sphene, apatite and magnetite, the garnet crystals are i n the upper size range - 129 -(.3 to .8 mm.), whereas the other minor constituents are generally smaller than .15 mm. Miscellaneous. In addition to the minerals described above, whioh have more or less general distribution, identifications of monazite, schorlite and wollastonite were made in single instanoes. Olivine was not found in any of the samples. Small rock fragments were recovered from the 20, 35 and 60 mesh screens during sieving of several samples. One such fragment mounted in thin section was found to be quartz diorite. In the coarse fractions of several samples, shapeless flakes of a light-brown colloidal-like material were noted. As these substances are non-crystalline, they were thought to be colloids, possibly of silica and iron. Carbonates. Sample number 2 has as much as 10$ carbonate content in some of the fractions and an average of 5% for the sample as a whole. Most of this is of organic origin. Small shell fragments occur in the coarser fractions and i t is in these that the carbonate content is highest. Mauve-colored, blade-like fragments of fibrous structure are to be found in the size range 0.1 mm. and up. These fragments effervesce readily in cold dilute hydrochloric acid, lack any recognizeable cleavage, have a dark mauve color and when crushed with a needle break up into a mass of thin silky fibres. They were identified as tiny fragments of shell of the clam Mytilus. Sample number 2 also contains small fragments of. calcareous algae. In addition to the calcareous algae and shell material, the carbonate con-tent of sample number 2 is also made up of soft white limey lumps ranging in size from 0.5 to 1.0 mm. Microfossils. A considerable variety of microfossils is to be found in Bute Inlet sediments. Except for sample number 2, the microfossil con-tent in the samples examined does not exoeed 1%, the sand fraction of PLATE II . . Photomicrographs - Bute Inlet Sediments and a S o i l Sample A. Thin section mount, showing plagioclase grain i n unsized quartz-feldspar fraction, sample 23. X-nicol^s, x 50. B. Bakelite mount, sample 22, unsized, chiefly quartz (q) and feldspar ( f ) . X-nicols, x. 50, C. Bakelite mount, s o i l sample, showing rock fragment inclusion. X-nicols, x 50. D. Air mount, unsized, sample 9, showing order of grain size. Quartz (q), feldspar.(f), biotite (dark grains), x 50. E. Air mount, unsized, sample 13A-1, showing grain size of quartz (q) and feldspar (f) as contrasted with biotite (b). x 50. F. Air mount, unsized magnetic fraction, sample 16, largely amphiboie (a), some garnet (g). x 50. P L A T E rollo t o 1. -1$ P 12. <) - 130 -sample 2, the exception, consisting of approximately 20$ microfossils, shell fragments and sponge material. Diatoms ranging i n size from 0.07 to 0.4 mm. were found i n a l l samples throughout the length of the fiord except i n sample 2j there i s no particular concentration i n any area. A. F. Szczawinski of the University of British Columbia Botany Department made an examination of some concen-trations of diatoms prepared during this investigation and reported them to be rich i n species of which the following, i n order of abundance, were identified: Actinocyclus cruciatus. Actinocyclus helveticus, Biddulphis, Hyalodiscus. Triceratium and Coscinodiscus. A l l of these species are from the class Bacillariophyccae. There are possibly many more species i n these sediments as only a few samples were prepared and the Bute Inlet sediments would appear to present excellent opportunities for the study of diatoms. Foraminifera tests were found to occur i n a l l samples. The most common genera are planospiral and t r i s e r i a l i n form. The tests average 0.1 mm. i n size. (See Plate IV and Plate III, E). Sponge material was also found i n a l l Bute Inlet samples. It varies in size from minute particles, passing through the 100 mesh sieve, up to large pieces one inoh or more i n size. Specimens submitted to Dr. W. C. Clemens of the University of British Columbia Zoology Department were classified as Aphrocallistes. Hexaxial spicules, which are always siliceous, were measured over a wide size range from 0.1 to 0.8 mm. and can be found i n most samples. Long thin s i l i c a threads, as much as 2 to 3 mm. i n length, were also noted to be of general distribution. Both forms were classified as sponge spicules. (See Plate IV). Small fragments of braohiopod shells were seen i n coarser fractions of some samples, especially near the mouth of the fiord. Calcareous algae - 131-tubes, as small as 0.1 mm. were found i n samples coming from the southern end of the fio r d . Echinoid spines (see Plate III and Plate IV) were observed i n several samples, particularly i n sample number 2 where white, rose and yellow-green forms were noted. Fragments of shell of the clam Mytilus were also noted i n sample 2 but were not seen i n any other sample. Bryozoa (Plate III) were found i n several samples taken from the south end of the fiord. Ostracods were noted only i n sample number 2 (see Plate IV). Bryozoa, ostracods and Mytilus fragments were identified by Miss Frances Wagner of the Geological Survey of Canada. Nothing was noted i n the detailed examination which could be related to the waxy material which periodically covers parts of Bute Inlet. These mineralogical and paleontological observations refer to the sand fraction of each sample. The minus 250 fraction of 10 samples was examined under high power and an estimate of mineral representation made. In every sample, the quartz-feldspar: biotite-amphibole ratio was found to be greater i n this fraction than i n the plus 250 mesh fraction. In several samples very l i t t l e biotite and amphiboie could be found. An attempt was also made under high power to find representatives of the clay mineral group, but nothing was noted that would suggest the presence of an appreciable clay mineral content i n the minus 250 mesh separate. The whole separate appeared to consist of tiny quartz and feldspar fragments, with a small percentage of biotite flakes and amphiboie crystals. In this examination, reference was made to the work of Nahin, Merril, Grenall and Grog (1951, p. 152) and Grim (1940, p. 9) TABLE X This table, together with the data of Figure I, A, gives a summary - 132 -of the mineralogical characteristics of 26 Bute Inlet samples. Figure I shows sample positions i n the Inlet. Figure I, B gives the results of a size analysis of the sand fraction and Figure I, C shows the relatively small percentage of sand as compared with the s i l t and clay fractions. Six samples were not analyzed mechanically as the samples were too small. Core samples are indicated by the letters (c.s.) and bottom samples by letters (b.s.) following the sample number. The examination of cores i n this i n -vestigation was restricted to surface or top layers of the core. No. 23 (c.s.) Plagioclase (average An. 36) quartz, brownish and greenish biotite, K-feldspar, small granodiorite fragments and colloidal materials. Minor amounts of zircon, garnet, pyroxene, magnetite, schorlite, epidote, soda amphiboie. No. 22 (c.s.) Plagioclase, quartz, biotite - some brown, but predominantly greenish, K-feldspar, small granodiorite fragments. Minor amounts of pyroxene, muscovite, magnetite, epidote, zircon, garnet, apatite, soda amphiboie. No. 20 (c.s.) Biotite, quartz, plagioclase, K-feldspar. Trace amounts of amphiboie, zircon, muscovite. Small siliceous sponge spicules are abundant. No. 25 (b.s.) Sample taken close to shore. Sample of insufficient amount for size analysis, but from microscopic work appears to be the coarsest sample examined. Wide range of sizes, from a peble l i inches i n diameter to fine s i l t . Plagioclase, quartz, biotite, K-feldspar, amphiboie. Minor amounts of zircon, sphene, garnet, muscovite, magnetite, apatite, epidote and wollastonite, In this sample there are about equal amounts of biotite and amphiboie, whereas i n sample 18, which i s much finer-grained, biotite far exceeds amphiboie; the importance of grain shape in .transportation is illustrated here. No. 18 (b.s.) Biotite, plagioclase, quartz, K-feldspar. Minor amphiboie, sphene, zircon, garnet and epidote. The plus 100 fractions of this sample are characterized by an unusually high peroentage of sponge material. No. 17 (c.s.) Plagioclase, quartz, biotite, K-feldspar, amphiboie. Minor amounts of zircon and sphene. No. 16 (b.s.) Plagioclase, quartz, biotite, amphiboie, K-feldspar, and quartz diorite fragments i n which plagioclase i s partially altered to epidote and calcite. Minor pyroxene, zircon, soda amphiboie, garnet, magnetite, epidote, apatite, sphene, wollas-tonite, monazite. This sample i s much higher i n amphiboie and PLATE -III Photomicrographs - Bute Inlet Sediments and a Soil Sample A. and B< Minus 200 plus 250 mesh fraction and plus 35 mesh fraction of sample 2, showing range of grain size in this sample. A: quartz, feldspar and amphibolej B: quartz and rock fragments, x 50. C. Sponge and echinoid spines, sample 18. x-nicols; x 50. D. Bakelite thin section of soil sample: quartz, feldspar and amphiboie. x 50. E. Foraminifera (f), quartz, feldspar and biotite, sample 1. x 50. F. Bryozoa (B), echinoid spine (E) and foraminifera (F), . quartz and mica, sample 1, -x 50 - 133 -TABLE X also i n the "accessory" or "heavies" than the average sample. The "accessories" constitute about 3% of the sample. No. 15 (b.s.) Plagioclase, quartz, biotite, K-feldspar. Minor amphiboie, sphene, zircon, muscovite. Not sized, but very fine-grained and similar i n texture to sample 13A-1. Large number of diatoms. No. 14 (b.s.) Plagioclase, biotite, quartz, K-feldspar, amphiboie, a few quartz-diorite fragments. Minor amounts of pyroxene, muscovite, zircon, sphene, epidote, garnet, soda amphiboie. Although there i s a considerable variety of "heavies", the total amount of these constituents i s much less than i n sample 16. No. 28 (c.s.) Quartz, biotite, plagioclase, K-feldspar. Minor amphiboie, muscovite and zircon. No. 13A-1 (b.s.) Biotite, plagioclase, K-feldspar, quartz. Minor muscovite, amphiboie and zircon. This and 13A-2 are the only samples i n which K-feldspar approximates soda plagioclase i n amount, with calcic plagioclase being of very minor content. No. 13A-2 (b.s.) Very similar to 13A-1 i n having a small sand fraction composed mainly of mica, feldspar and quartz with the feldspar being equally divided between K-feldspar and sodic-plagioclase. Not sized, but the sand fraction i s very close i n texture to that of 13A-1. No. 12 (b.s.) Plagioclase, quartz, amphiboie, biotite, K-feldspar. Minor constituents include pyroxene, epidote, sphene, zircon, soda amphiboie, apatite and magnetite. This sample i s similar to Nos. 16 and 14 i n that i t has a large amount of heavy minerals -about 3% - and a relatively small amount of biotite. No. 11C (o.s.) This sample was not sized. Composed principally of plagioclase, biotite, quartz and orthoclase. Minor constituents are amphiboie, muscovite and zircon. A comparison of Nos. 12 and 11C again illustrates the importance of shape and S.G. i n trans-portation, sample 12 having come from a point somewhat closer to three inflowing streams than 11C. The latter i s rich i n diatoms and is one of several samples containing long s i l i c a threads -sponge spicules. No. 11A (b.s.) Plagioclase, biotite, quartz, amphiboie, K-feldspar and a few quartz-diorite fragments. Minor amounts of muscovite, sphene, zircon and garnet. The sample contains a relatively large amount of sponge spicules and other sponge materials i n the coarsest fractions. No. 11B (b.s.) Plagioclase, quartz, biotite. Minor amphiboie and zircon. The contrast between 11A and 11B i n mineralogy and texture indicates a possible rapid change i n current conditions - 134 -TABLE X within a distance of less than 2000 feet. No. 10 (b.s.) Insufficient material for sizing. Relatively fine-grained. Plagioclase, quartz, biotite, K-feldspar and very minor amphibole with no accessories other than zircon. The fine-grained features of this sample are anomalous i n view of the fact that the sample position i s not far from the mouth of Orford River. Further sampling would be required before the characteristics of the sediments of Orford Bay could be estimated. No. 9 ( c s . ) This sample i s quite similar to number 20 In that i t i s very high i n mica and has a minor sand fraction. Nos. 6, 7, 8 ( c s . ) These samples are quite similar, being composed principally of biotite, plagioclase, quartz and K-feldspar with very minor amounts of amphibole, muscovite, zircon and sphene. Diatoms are plentiful i n a l l samples. Some foraminifera and echinoid spines noted. No. 3 (b.s.) Plagioclase, biotite, quartz and K-feldspar. Minor amounts::of amphibole, garnet and sphene. Echinoid spines noted. No. 2 This sample i s unique i n i t s wide size range (see Plate III, A, B.), poor sorting, large microfossil and shell content, large accessory mineral content, relatively low biotite and quartz-feldspar percentage. It consists of plagioclase, microfossils, shell fragments, quartz, amphibole, biotite, car-bonates and small rock fragments of quartz diorite and andesite. Carbonates as charted on Figure I, A are largely i n the form of small amorphous carbonate masses, mauve fragments of Mytilus. and larger shell fragments, although a small component of the carbonate material i s i n the form of calcareous algae. Heavy accessories include pyroxene, soda amphibole, garnet, epidote, magnetite, zircon and apatite. Foraminifera are p l e n t i f u l . Echinoid spines, siliceous sponge spicules, bryozoa and ostracods are well represented. No diatoms were noted. No. 4 (b.s.) Plagioclase, biotite, quartz, K-feldspar and amphibole, with minor muscovite, and a relatively large amount of zircon. In contrast to sample number 2, the microfossil content i s low. Foraminifera and bryozoa are present. No. 1 ( c s . ) Plagioclase, quartz, biotite, K-feldspar and amphibole. Minor amounts of apatite, magnetite and zircon. Although not as rich i n microfossils as number 2, there is a wide variety of types i n this sample, calcareous algae being particularly abundant, foraminifera and siliceous sponge spicules conspicuous, echinoid spines and bryozoa easily observed. From data contained i n the above Table, Figures IA, IB, IC and I, certain general conclusions regarding Bute Inlet samples are indicated. - 135 -PLATE IV Microfossils - Bute Inlet Sediments Foraminifera, siliceous sponge spicules, echinoid spines and ostracods. x 35. Three general sub-groups of sediments can be discerned within the fiord. Samples 23, 22, 20, 18, 17, 27, 15, 28, 13A-1, 13A-2, 11C, 11-B, ULA, 10, 9, 8, 7, 6, 3, At and 1, although having a fair range in mediam diameter as well as certain mineral compositional differences, are essentially similar in that at least 95$ of the mineralogical content consists of plagioclase, biotite, quartz and K-feldspar; there is a minor amount of amphiboie and very minor amounts of certain heavy minerals; and furthermore, biotite predominates in the coarse fractions, plagioclases in the fine-- 136 -grained fractions and quartz reaches a maximum in the middle-size fractions. Secondly, samples 25, 16, 14. and 12 differ markedly from samples of the f i r s t group in having much larger percentages of amphibole and other "heavies" and a relatively small percentage of biotite. Thirdly there is sample number 2, which is somewhat similar in its mineral composition to samples of the second group, but has a high microfossil content and is coarser-grained than samples of either f i r s t or second groups. It is interesting to note that sample positions of the second group are close to small shore-line streams flowing down steep mountain sides, through rocks, which for the most part are of a metamorphic character, whereas sample positions of the f i r s t group are at varying distances, as reflected in the range in median diameters, from streams and rivers flowing through Coast Range intrusive rocks, which do not furnish the heavy minerals for transportation to the sea that are supplied by the metamorphic rocks. Sample number 2, constituting the third group, is in close proximity to the Arran Rapids, through which currents flow, presumably having passed metamorphic rocks 6f Mt. Tucker, a possible source of the heavy minerals found in this sample. This mineralogical study has therefore indicated a pattern which can be explained in terms of shore-line and inland geology and topography. Similar patterns in ancient sediments might be visualized in terms of such combinations of lithological and water-transportation factors as those existing in the Bute Inlet locality. It is of course evident that to establish definitely a mineralogical pattern such as that suggested here, would require many more bottom sample analyses, detailed knowledge of shore-line and drainage-coarse geology, and an understanding of the main current distributions. The data presented here, however, afford a partial basis for evaluating the relative effects of the factors of lithology, topography, - 137 -depth, river flow and ocean currents on the mineralogy of the fiord sedi-ments . Shape and Roundness Shape and sphericity are terms descriptive of the form of a grain; roundness is a measure of the curvature of the particle boundaries. The development of the degrees of sphericity and of roundness may vary con-siderably in a given particle. Wadell (1935, pp. 250-280) and many others have made studies of these two properties of sediments and numerous methods of measuring them have been recorded. Twenhofel and Tyler (1941, pp. 134-139) and Krumbein and Pettijohn (1938, pp. 277-302) summarize some of these methods. Shape and roundness criteria have a value in correlation work on recent sediments (Edelman, 1939, pp. 322-342) as well as on ancient sedi-ments (Rittenhouse, 1946, pp. 1192-1197). According to Pettijohn (1949, p. 53) the roundness of a clastic particle sums up its abrasion history. Sphericity, on the other hand, more largely reflects the conditions of deposition at the moment of accumulation, though to a limited extent sphericity is modified by abrasion processes. Shape therefore is a mere important factor in the-sorting history of a deposit. This is illustrated by Plate II, E in which grains of micas predominate in the course fractions of a sample whereas quartz and feldspar make up most of the fine-grained portion. Shape and roundness studies should be made on one mineral only. The outline form of a mica plate is particularly difficult to interpret owing to the properties of the mineral, its softness, capacity to bend, elasticity, cleavage and ease of foliation. Eibrous and needle-shaped minerals often retain their form to some extent regardless of weathering - 138 -and transport. Feldspars, on account of their cleavage and twining, are liable to show an angularity greater than average for distantly transported mineral grains. In highly weathered residual mantles, on the other hand, feldspars seem to show more rounding than would normally be expected because of their susceptibility to chemical attack, mostly concentrated on corners and edges, and the absence of breakage in such sediments. Quartz particles have no properties which throw serious doubts on the interpretation of their shape or roundness. Consequently in this project, observations were made on quartz particles only. An attempt to measure shape and roundness in quartz-feldspar fractions by attaching a camera bellows with ground glass screen onto a petrographic microscope and making tracings of mineral grain image pro-jections from the microscope on the glass screen was not successful because of the inability to distinguish between quartz and feldspar at a l l times. In order to be sure quartz particles were being observed, the malachite stain test was used on the quartz-feldspar fraction. Outline drawings were made using the carmera lucida method, which was found to be a very quick means of getting a grain outline. Magnification usedi was xl20. Inasmuch as roundness is a criterion particularly of abrasion history, i t was considered to be not as important in the study of Bute Inlet sediments as shape. A l l particles reach the Inlet with a certain degree of roundness as imparted by traction transport and l i t t l e change would take place in this property within the Inlet. Furthermore roundness studies on particles less than l/lO mm. are said to be of l i t t l e value as these particles are predominately angular. However roundness measurements were recorded by means of comparing carmera lucida outlines with the stan-dards given by Pettijohn (1949, p.59). Table XII shows the results of - 139 -TABLE XII Roundness Indices - Bute Inlet Sediments Sample Particle Size i n Mm. Weighted No. .06-.07 .07-.10 .10-.15 .15-.20 .20-.42 .42-.S3 Average 23 .38 .42 .55 .58 .62 .42 22 .35 .51 .60 .62 .64 .44 18 .20 .35 .45 .47 .53 .26 16 .25 .34 .40 .48 .58 .65 .40 12 .25 .33 .40 .51 .58 .46 11A .2-4 .37 .43 .49 .55 .34 roundness studies of Bute Inlet samples. The low valuos are indicative of a lack of extensive abrasion. Shape or sphericity was studied i n more detail from camera lucida drawings. Figure 10 shows a few representative outlines taken from camera lucida drawings of sample number 16. The method used i n measuring shape was that of Tic k e l l (1939, pp. 1233-38), who defines shape i n terms of the ratio of area of particle i n the plane of observation to area of cir c l e circumscribing the particle. The area of a particle was measured by placing transparent squared paper over the camera lucida drawing and counting the squares. The area of the circumscribing cir c l e was determined by placing over the grain drawing a sheet of transparent paper on which a series of concentric circles were drawn and selecting the appropriate c i r c l e . About 25 grains were drawn and measured i n each size fraction of each sample. Shape studies of Bute Inlet sediments showed that this quality of a particle decreases i n value with decrease i n particle size (see Table XIII). A tendency was found also towards progressive sorting. In general particles - 140 -TABLE XIII Relation Between Particle Size and Sphericity Bute Inlet Sediments Sample Particle Size in Mm. No. .06-.07 .07-.10 .10-.15 .15-.20 .20-.42 .42^  23 .57 .61 .63 .64 22 .52 .56 .63 ,67 18 .50 .57 .61 .63 16 .31 .54 .57 .67 .72 .73 12 .49 .51 .55 .62 .68 .70 11A .40 .57 .59 .61 TABLE XIV Weighted Average Sphericities Bute Inlet Sediments Sample No. Sphericity Sample No. Sphericity 23 .59 12 .58 22 .55 11C .56 20 .59 11B .52 18 .52 11A .49 17 .57 10 .63 16 .64 9 .60 14 .63 7 .53 28 .59 6 .53 2 .64 4 .51 of highest sphericity occur in samples taken from localities nearest mouths of inflowing streams with decrease in values with distance from the point of inflow. Table XIV gives a value for the weighted average sphericity of 18 samples and while the spread is not great, a comparison of sphericity - 141 -value with sample positions as shown in Figure I shows evidence of pro-gressive sorting, especially in the lower part of the fiord. These Tables also show that, as a group, quartz particles less than 0.83 mm. have a relatively low sphericity. Rittenhouse (1943, pp. 79-81) recommends a visual comparison with standard charts for both sphericity and roundness, gives a chart for deter-mining visually the projection sphericity of sands and suggests the use of Krumbein's roundness chart (Krumbein, 1941, pp. 64-72). Rittenhouse states that considering the rather large sampling error to which sphericity and roundness studies are subject, i t seems probable that visual comparisons w i l l yield data of sufficient accuracy for many investigations. It is suggested that this visual method be used in preference to the method of Tickell which was employed during the study of Bute Inlet sediments, as the camera lucida drawings and the computing of areas are very lengthy pro-cedures for a large number of samples. Studies of sphericity and roundness of stream and river sediments provide more opportunity than do marine sediments of working out inter-relationships between these two factors and their significance in processes of abrasion and selective transport. Pettijohn (1942, pp. 43-63) discusses a number of these relationships. Some Applications of Laboratory Findings Although reference has been made principally to recent marine sedi-ments when outlining laboratory procedure, many projects concerned with other types of recent sediments could be carried out using much the same laboratory facilities and techniques as referred to in this report. The following remarks are included to illustrate this point. - 142 -Teohnically, soils can be called sediments because they are aggre-gates of particles that have come to rest i n some place after having been transported l a t e r a l l y or vertic a l l y , although usually for very short distances. They can also be examined as part of sedimentary projects as they have many of the properties of recent or unconsolidated sediments. Furthermore, geologic studies can contribute to an understanding of s o i l processes. During this investigation some petrographic work was done on s o i l thin sections prepared by W.R.G. Chauncey, University of British Columbia Agronomy Department, i n connection with a study of Vancouver Island soils at Duncan and Alberni. These thin sections were prepared by mounting with bakelite as described previously under the heading of "Preparation and Mounting". Microscope examination provided information on shapes and relative sizes of mineral grains and degree of alteration of larger grains. Thin sections were examined from samples of B and C horizons of soils In the Port Alberni and Duncan areas. These soils have a common characteristic in that they have "shot" structures i n the B horizon. The "shot" structures are small pea-size aggregates indicative of certain leaohing processes i n the B horizon. Other similar structures are higher i n iron and are called "pseudo-shot". Thin-sections studies were directed towards a petrographic interpretation of the differences i n these two structures and to a general description of the vis i b l e mineral particle content. Examination of "shot" structures of both Duncan and Alberni so i l s showed that 10 to 15% of the mineral particles were larger than l/32 mm. but few i f any grains were larger than mm; and that of the observable mineral grains, about 80% were quartz and feldspar grains. No albite twinning was noted and feldspar grains had ragged edges and surface alteration. - 143 -In contrast, thin sections of the material surrounding the shot in these two soils showed a much higher mineral-grain content - 35$ for Duncan and 30$ for Alberni - of mineral particles greater than l/32 mm. and also much higher percentages of ferromagnesians - 30$ ferromagnesians in the Duncan and 35$ in the Alberni. The feldspars appeared to be less altered and they consisted of at least 10$ plagioclase. Thus, this petrographic work was able to demonstrate that the "shot" structure represents small zones which have been more extremely leached and in whioh the breakdown of ferromagnesians and of basic feldspars has been more extensive than in the B horizon as a whole. A further aid to the study was given through a comparative examination of "shot" and "pseudo-shot" thin sections of Duncan soil. The particles studies were in the range of l/lO to l/4 mm., the coarser fractions having been concentrated for this particular examination. A count of about 1500 grains was made for each structure and the "shot" was found to contain 8$ ferromagnesians whereas the "pseudo-shot" contained 11$. This agreed with chemical analysis data of the clay fraction which showed the clay fraction of the "shot" to have a higher iron content than that of the "pseudo-shot", thus indicating a greater breakdown of ferromagnesians in the "shot" and transfer of iron into the clay fraction. In addition to these two suggestions relating to the origin of the "shot" and the difference between the two shot structures, several general conclusions were reached regarding the use of the petrographic microscope on bakelite thin sections. These sections reveal textural and structural features very well (see Plate II, B and C). They are also suitable for permitting examination in detail of the larger mineral grains and for getting a general idea of the mineral composition as indicated by larger - 144 -grains (sea Plate III, D). However, for more accurate determinations of the mineral content, separation of sand fraction particles, staining and mounting techniques, such as described earlier in this Part for recent marine sediments, are essential. The thickness of the bakelite stain tends to obscure the smaller grains making accurate identification of the mineral composition impossible. A detailed examination of "shot" and"pseudo-shot" carried out by such methods as described in this report could provide important information as to the fundamental differences of these two structures. In addition, clay mineral identification by methods described in Part VI would further assist in the solution of a very complex pedo-logical problem. This is an illustration of the meeting place of geology and pedology in an investigation of unconsolidated sediments, with the geological laboratory furnishing petrographic data and the soils laboratory chemical and organic data. It would seem that the solution of such a problem as that of the "shot" and "pseudo-shot" structures might well be reached through a combination -of geological and pedological methods. Engineering projects concerned with stream channel control for the purposes of providing deeper water for navigation, of hastening flood run-off, of confining flood waters within restricted limits, of improving drainage of lands adjacent to a river or stream, and of checking bank erosion, can be assisted by geologic research in the processes of sedi-mentation. Such research can contribute fundamental data to stream control problems. In the matter of erosion, geological field work supplemented by detailed mineralogical and mechanical analyses can point to the main sources of river sediment load and provide suggestions for erosion control. Happ (1950, pp. 319-335) discusses measures that have been taken in stream-- 145 -channel control in some rivers in the United States. The Fraser River area offers considerable scope for research in sedimentation along lines being carried out for other major rivers. During such research, much information could be obtained through petrographic studies of unconsolidated sediments. In connection with the emplacement of engineering structures on beaches, sedimentation effects must be examined. Determination of source areas for beach materials and analyses of factors which may modify normal sedimentation processes following installation of barriers are important geologic contributions to beach engineering. Investigations of strength of sediments are of prime importance in the field of soil mechanics, in which the term "s o i l " includes unconsolidated sediment, regolith and mantle rock. Soil mechanics studies are therefore undertaken in connection with engineering problems associated with highway engineering, foundations, dams, and soft ground tunnels. A reference to one or two aspects of each of these engineering undertakings illustrates the application of geologic methods of sediment study to such projects. In the building of dams, borrow material for earth construction must have suitable moisture content, mineral composition and physical properties such as grain size, cohesive strength, angle of internal friction, and plastic limits to meet the requirements of workability, strength, durability and impermeability. A geologic investigation to ascertain the suitability of earth materials for dam construction w i l l report upon the fundamental properties of sediments and laboratory work w i l l assist in relating these properties to soil mechanics criteria. Appraisal of the suitability of foundations for dam construction should be based in part on geologic inter-pretation of a l l test work done, including identification of clay minerals. Construction work on dams, on highway bridges and on tunnels of various types requires geologic approval on the suitability of materials to - 1-46 -be used in concrete and masonry. Deterioration due to alkali-aggregate reaction is usually the direct result of the mineralogy or petrography of the parent rock. Few, i f any, rocks are inert when enclosed in,concrete. The mineralogic and chemical composition and internal texture and structure of* particles therefore control the physical and chemical properties of aggregates (Rhoades, 1950, p. 4-62). In the investigation of landslides, the geologist can furnish an appraisal of the degree of stability of slope and a description of the geologic and hydrologic conditions. An important part of this investigation is a determination of the nature of clay mineral content. Engineering projects scheduled for location near large faults require geologic approval before construction begins. Examination of fault material from the points of view of texture and mineralogical composition may give information on the past history of the fault and the nature of the clay content may indicate the water barrier possibilities. Ground water movements are of importance in water supply and also must be taken into consideration in planning engineering structures. The ordinary geologio descriptions of sediments are of limited value in judging their permeability; consequently the U; S. Geological Survey has adopted the practice of making standard laboratory tests of permeability, porosity and mechanical composition - with respect to grain size and assortment - of materials which are being investigated in connection with the production and control of ground water (Meinzer, 1950, pp. 152-179). The investigation of gravel, rock, clay and other materials for both subgrade and highway surfaces is the most important application of geology to highway construction (Bean, 1950, pp. 181-193). An acourate estimation of the value of an aggregate can only be made by the combination of en-- 147 -gineering strength tests and data obtained from geologic investigation of source materials. Here again, sedimentary petrography may play an important part by ruling out materials which would have an injurious effect on concrete. In a l l of these undertakings, geologic investigations provide fundamental or basic data which help to establish working principles for engineering usage. The measuring of various properties of unconsolidated sediments in the laboratory is an important step in the analysis of field data and in making i t available for technological purposes. - 148 -PART VI Some Specialized Analytical Methods Although the petrographic microscope and the binocular microscope provide the means of gathering much mineralogical information during a laboratory examination of unconsolidated sediments, certain other instru-ments and techniques are essential i f complete information is to be obtained, especially when very fine grained sediments, such as the clays, are being investigated. Mention is made of four laboratory processes which are finding much use i n sedimentary studies. Spectrograph!c Analysis Spectrographic analysis has a wide application i n many types of research and i n many industries. In geologic investigations i t can be used in conjunction with X-ray analysis i n mineralogical identifications and a consequence of this i s a usefulness i n correlation work especially where lithologic or paleontologic markers or identifiable zones are lacking. Its a b i l i t y to make quantitative determinations of trace elements i s also important i n correlation work. It i s i n this latter role that i t is being used along with geologic mapping, geophysical surveys and structural studies as a laboratory method of gathering information for map compilations in Western Canadian o i l f i e l d s . In principle, spectrographic analysis i s based on the fact that each element i n the incandescent vapor state emits colored l i g h t which can be analysed by a spectrometer to produce on an exposure plate a characteristic group of black lines whose positions and spacing are diagnostic. In a study of unconsolidated sediments several uses might be made of the spectrographic analysis method. It could be used i n conjunction with X-ray and other types of analyses i n the investigation of clay minerals; - 149 -i t has a use i n aiding i n the identification of unknowns i n the sand fractionj i t may be used to determine the presence and measure the amount of trace elements i n the sediment as a whole. In the laboratory work on Bute Inlet sediments, i t was decided to use spectrographs analysis to measure the amount of three trace elements - manganese, strontium and magnesium - i n order to have a record of the percentages of these elements in fiord sediments and also to make note of any relationship that might be found between these percentages and textural or mineralogical data. If studies of many present day environments of deposition included spectrographs analysis of sediments, information on trace element chemistry obtained might have important uses i n the solution of stratigraphic problems i n ancient sediments. Manganese was selected as one of a number of elements which might be diagnostic as i t s presence i s a function of oxidation and reduction con-ditions. In sediments of relatively high organic matter the decomposition processes cause a reduction of manganese sulphate to the sulphide. This i n turn i s decomposed by carbonic acid forming soluble manganese bicarbonate, which remains i n solution u n t i l i t meets with an excess of oxygen, as i n the waters overlying muds or on the surface of current swept ridges. It i s there precipitated as a higher oxide of manganese which may again be reduced and go into solution and be precipitated elsewhere. Thus there w i l l tend to be an accumulation of manganese i n any region which is peculiarily free from reducing matter. The Bute Inlet sediments were therefore tested quantitatively to see i f any particular relation existed between the amount of manganese and organic matter and i f there was any measurable variation with change i n grain size. Strontium and magnesium were selected as they are among the several trace elements used i n stratigraphic studies i n connection with present day - 150 -o i l search i n ancient sediments. Tests were run on five samples in the Spectrographic Laboratory of the Mines Branch, Department of %nes and Technical Surveys, Ottawa. A Grating Spectrometer was used. A 10 milligram sample was mixed with a Ifi milligram buffer composed of equal amounts of graphite and potassium sul-phate. The sample was placed between graphite electrodes and under a potential of 300 volts and direct current of 10 amps, was completely vala t i l i z e d . After developing the exposure plate, line densities were measured on a densitometer and element percentages computed. Although the spectrographic method used can be described generally as a powder method, special provision i s made i n the procedure for uniform and complete vo l a t i l i z a t i o n by burning the sample i n an a i r - j e t t i l l i t i s completely used up. The lines produced on the exposure plate are exceptionally well-defined and easily measured. Density readings for these samples were made in a Leeds and Northrop Recording Microphotometer with Recording Unit. Density being a function of concentration, the percentage of an element is determined by referring to calibration ourves of known quantities. Table XVI shows the results of the analyses for manganese, asd magnesium^strontium on five samples. Values for organic matter content and median diameter for each sample are also shown. Although there i s l i t t l e spread i n the manganese percentages, sample number 1 is highest i n manganese and lowest i n median diameter, whereas samples 23 and 2 are on the low end of the manganese range and at the same time are the coarsest i n grain size. No conclusion can be drawn from comparison with organic matter content. The values for strontium are quite uniform, except that for sample 9, which i s less than one half the value for sample 23. The magnesium values also show l i t t l e variation. As only five samples were analyzed, manganese, strontium and magnesium values shown in the Table are presented as an - 151 -TABLE XVI Manganese, Strontium and Magnesium Content Bute Inlet Sediments Sample No. Median Dia.Mm. Organic Matter % Manganese % MnO % Strontium % Magnesium " % 23 .022 .548 .07 .09 .07 1.1 17 .014 .752 .10 .13 .06 1.5 9 .011 1.390 .10 .13 .02 1.2 2 .060 4.480 .08 .10 .06 1.1 1 .009 3.190 .12 .16 .05 1.4 indicator of the order of amounts which might be expected i n recent marine sediments i n a British Columbia fiord rather than as a means of measuring va r i a b i l i t y i n terms of other c r i t e r i a . It i s interesting to note that the values of MnO for surface layers of deep-sea sediments of low calcium carbonate content are said to be i n the order of 0.51$ (Recent Marine Sediments, 1939, p. 384) and for l a s t - g l a c i a l and post-glacial sediments values of 0.52 and 0.12% respectively are given (Recent Marine Sediments, 1939, p. 393). The manganese values determined for Bute Inlet sediments compare favorably with these values for post-glacial sediments. , Electron Microscopy The electron microscope i s being adapted to a great number of sci e n t i f i c uses for both research and industrial projects. One of i t s main uses i n geologic work i s i n the study of clay minerals, along with X-ray diffraction and differential thermal analysis procedures. The eleotron source i n this microsoope i s an electromagnetic gun from which a stream of electrons pass through a condenser c o i l , the - 152 -mounted specimen, an objective c o i l and a projector c o i l onto a photo-graphic plate. The instrument i s also equipped with a viewing screen for making selections of fields for photographing. The electron beam is con-centrated on a specimen by the magnetic f i e l d produced i n the condenser-lens c o i l . After passing through the specimen, the electrons are focused by the objective-lens c o i l into an intermediate image, and the projection lens c o i l produces a further magnified image for photographing. Variations i n the electron scattering power in different parts of the specimen give rise to variations of intensity i n the corresponding parts of the image. These electron optical images provide exact information about the shape and size of finely divided matter. The chief limitations of the method i n examining clays l i e i n the interpretations of the obser-vations and i n the d i f f i c u l t i e s of specimen preparation. Consequently the microscope's main use to date i n clay research has been i n a study of crystal characteristics of a clay mineral once identification has been made by X-ray or differential thermal analysis. The following procedure was used by University of B r i t i s h Columbia Physics Department technicians i n the preparation of several Bute Inlet samples for examination by the electron microscope. Dispersion was carried out i n d i s t i l l e d water and sufficient settling time was allowed to insure removal of a l l but minus 2 micron size particles from the suspension. Using a micropipette, a drop of the suspension was placed on a stainless steel 200 mesh grid, -£-inch i n diameter, which was floating on a thin collodion f i l m over d i s t i l l e d water. The grid with collodion backing was removed from the water and the drop of dispersion liquid containing the specimen allowed to dry on the grid. In order to provide additional contrast and a three-dimensional aspect to the photomicrograph, a technique of shadow casting was employed. - 153 -This was carried out by slowly evaporating about % gram of pure electrolytic chromium metal from a conioal tungsten wire basket at a pressure of less than 10-5 mm. of mercury i n a metal evaporator. As the atoms of chromium condense, elevations and depressions on the surface of specimens cast shadows characteristic of the contours depending on exposure to or shelter from the chromium vapor. When the specimen is placed i n the electron micro-scope, transmission of the incident beam of electrons is a maximum where no metal has been deposited, but where thick deposits occur, electron scattering i s a maximum and few or no electrons are transmitted by "the specimen. The angle of deposition of the metal was set at 15° by raising the filament i n the evaporator above the plane of the specimen. The evaporator used was a copper tube, 14 inches long and 6 inches i n diameter, and evacuation was carried out by an ordinary vacuum pump operated by a -5- h.p. motor for a period of about •§• hour. Tungsten makes a suitable holder for chromium as boiling points are 3300°C. and 1900°C. respectively. When the shadow casting was complete, the mount was placed i n the electron microscope and a vacuum created. The specimen was then ready for viewing at 3000 diameters and a suitable portion for photography was selected. Focusing was accomplished by changing the voltage, i.e. the velocity of the electrons. Photography must be carried on at low intensity of electron beam i n order to avoid damage to the collodion mount. Kodak lantern slides, "medium", are generally used i n electron microscope development work, but "contrast" plates can be used with effect when contrast between specimen and background i s low. The prints produced during this examination gave a magnification of 3000 and were viewed i n an enlarger at 12000 diameters. Several points are to be noted i n connection with preparation of mineral specimens. The material to be studied should be ground as finely - 154 -as possible i n an agate mortar and great care taken to ensure a suspension of only the finest particles. At least eight separate specimens from each sample are required i n order to make allowance for the d i f f i c u l t i e s of getting good dispersions of representative samples on the mount. Good particle distribution on the fi l m i s essential to effective study of grain shape and outline. Nahin, Merril, Grenall and Crog (1951, p. 153) recommend photographing 10 different f i e l d s on two plates of five frames eaoh and the use for study of at least six photographically acceptable frames. Details of preparation are also given i n Preliminary Report Ko. 6 (1950) of the American Petroleum Institute and an excellent series of electron photomicro-graphs of clay mineral standards i s included i n this A;P.I. report. Of the few micrographs of Bute Inlet sediments that were taken with the electron microscope, none showed the hexagonal plates characteristic of kaolinite, the cylindrical forms of halloysite, the lath-like development of hectorite and montronite, the irregular flakes with hazy outline of montmorillonite nor the similar but sharper-outlined flakes of i l l i t e . Comparison was made with a l l available micrograph illustrations of standard clay minerals and reference made to such c r i t e r i a for identification as that given by Bramago et. a l . , (1952). It should be remarked, however, that the instrument used plus the allowable enlargement only gave a magnifi-cation of 12,000 diameters, whereas current research on clay minerals i s carried on at magnifications up to 45,000. It i s interesting to note that Legget (1948, p. 99) i n a study of some Canadian s i l t s reports that photographs by electron microscope failed to disolose any of the typical particle shapes of the true clay minerals, even though mechanical analysis showed a content of clay-sized particles of as much as 20% i n some glacial deposits of the Canadian shield, and he - 155 -concludes that the sediments examined consist of "roc!: flour", i.e. granular particles of relatively fresh rock minerals, despite their small range size. X-Ray Diffraction X-ray diffraction can be used i n conjunction with the petrographic microscope to work out mineral identities i n the sand-size fractionj i t also is indispensable i n the study of clays i n which the combination of differen-t i a l thermal analysis and X-ray techniques forms possibly the most effective method of clay mineral identification. X-ray diffraction techniques i n the study of crystalline materials were f i r s t evolved about 35 years ago, though they have just come into common use within the past few years. The use of the X-ray method i n studies of crystalline substances is based on the fact that when a beam of X-rays i s passed through a crystalline substance, the beam i s reflected and refracted from the planes of atoms which make up the crystal. The X-rays emerge from the crystal as a series of beams which can be recorded on a photographic film as a series of lines or dots, depending on the details of the procedure followed and the character of the material. The position, intensity and number of beams emerging from any crystal substance depends on the character of i t s atoms and their arrangement i n the substance. The day minerals can be studied by X-ray as they have different atomic structures and therefore yield different X-ray patterns. In this project, X-ray work was confined to several tests of the clay-size fraction to see i f a clay mineral identification could be made. Of the clay mineral identifications that have been made on sediments that are accumulating on ocean floors, the most common mineral i s i l l i t e . Kaolinite is also widely distributed but generally less abundant than i l l i t e and montmorillonite i s usually absent or of very minor importance (Grim, -156 -1942, p. 260). The clay content identity work was undertaken to see i f any clay minerals of determinable amounts exist i n Bute Inlet sediments. The most common minerals of clays are quartz, calcite, mica, kaolinite, halloysite and montmorillonite. Other constituents are dolomite, feldspar and hormblende. Quartz and carbonates are quite readily detected on the film, but i n the presence of a large amount of quartz, feldspar can easily by missed and the different feldspars cannot be separated as the l a t t i c e constants l i e too close together. Kaolinite i s relatively easy to identify but montmorillonite and haloysite, i f i n minor amounts, present considerable d i f f i c u l t i e s i n detection by the X-ray method. In,"general, any constituents less than 5$ are d i f f i c u l t of identification i n X*ray work as the dilution i s so great that no interference figures can be formed. In preparing a sample of Bute Inlet clay-size material and i n carrying out the X-ray procedure, the following steps were taken. The sedi-ments were put into suspension i n d i s t i l l e d water and allowed to settle t i l l everything courser than two microns had settled out (see Krumbein and Pettijohn, 1938, p. 166). The suspended material was then allowed to settle out, the bulk of the liquid decanted off and the remainder allowed to evaporate at room temperature. The sediment sample so obtained was mixed with about 10$ by volume of collodion and then rolled between two microscope slides to give a rod 0.5 mm. i n diameter. A small amount of a plastic cement, such as duco cement, might be used i n place of collodion. Following mounting of the specimen i n a diffraction camera, an X-ray-diff-raction pattern was recorded on fi l m by using an apparatus with provision for a high potential of about 50,000 volts. This equipment consists essentially of a line voltage stabilizer, an autotransformer to regulate the high potential, controls, r e c t i f i e r and X-ray tubes. The X-ray pattern - 157 -recorded on the film was measured and the data used to determine inter-planar spacings or unit c e l l dimensions. The r a d i i of a l l lines i n the pattern were measured and the Bragg angle obtained from tables based on a relationship between the line radius and the camera radius. This i n turn gave, from Bragg's law, a value for the Interplanar distances. In addition, the relative line Intensities were evaluated visually. After the pattern of the unknown had been measured, oonverted into interplanar spacings, the intensity of the lines estimated and at least the three strongest lines identified, mineral identification was attempted by making reference to the Hanawalt card-files index system. X-ray diffraction examination of several Bute Inlet sediments did not reveal any clay mineral content. The minerals identified, i n order of abundance, were soda plagioclase, quartz, and biot i t e . No definite con-clusions from X-ray data can therefore be presented regarding identities of clay minerals In Bute Inlet sediments. It can be inferred, however, that such clay minerals as might be present must constitute a minor per-centage of the minus two micron fraction, possibly not i n excess of about 5%. Differential Thermal Analysis Multiple- differential thermal analyses were f i r s t made by Le Chatelier i n 1887, but i t was not u n t i l the late 1930's that the method began to be used for semi-quantitative study of clay minerals. Today this method of clay mineral study i s receiving wider recognition. It i s also suitable for the study of certain other minerals, such as the carbonates, and w i l l readily identify minerals such as quartz and feldspar which commonly make up sizeable percentages of clay materials. - 158 -The differential thermal analysis method makes use of the fact that the important clay minerals are primarily hydrous aluminum and/or iron silicate compounds, and when they are heated to the fusion point they are subject to a series of thermal reactions which accompany the loss of water and changes in crystal structure. The method is therefore based on the effect of these reactions; and distinction among the various clay minerals is possible because the intensity of the thermal reactions and the tem-perature at which they take place are not the same for a l l clay minerals as each contains different amounts of water which are lost at different temperatures and because a l l clay minerals do not undergo the same changes in crystal structure on heating. The procedure in testing consists of heating the clay material at a constant rate up to 1000°C, or as close to fusion as possible and recording, by suitable devices, the intensity of endothermic and exothermic effects and the temperatures at which they take place. A number of references can be cited to illustrate the applicability of these thermal principles to various fields of research. Grim and Rowland (1944, pp. 1-23), have prepared thermal curves for many clay and non-clay minerals of clays and shales to illustrate the suitability of the method for evaluating the properties of clays and shales in plant control and in prospecting for suitable materials for the ceramics industry. Soil surveyors find the method of value in completing their information on soil types. The Geological Survey of Canada is currently using this laboratory method as an aid in correlation studies in the Quebec Labrador Iron Ranges. Differential thermal analysis also finds a use in research work on crystal structure of the clay minerals (Grim and Bradley, 1948, pp. 13-19). Smothers and Chiang (1952, pp. 384-396) illustrate the applications and limitations of the method in the study of lignites. Lovering (1949) has - 159 -recorded thermal curves for 27 secondary minerals during the course of a study i n rook alteration as a guide to ore. In general, di f f e r e n t i a l thermal analysis i s of value whenever qualitative and semi-quantitative data are required on clay minerals, the hydrous oxides of iron, aluminum and manganese, the cargonates and the zeolites; i n addition many other uses are currently being investigated. Differential thermal analysis i s usually used i n conjunction with X-ray analysis: X-ray data help to indicate a general clay mineral group; thermal analysis curves may be used to get quantitative data on mixtures not readily available from X-ray diffraction studies. The various clay minerals yield sufficiently different peaks to make the di f f e r e n t i a l thermal analysis method particularly useful, and when a specimen i s relatively pure, preliminary identification by thermal curves i s comparatively simple. D i f f i c u l t i e s encountered in analyses of clay mineral mixtures are explained by Grim (1948, pp. 5-11) i n a paper i n which he presents thermal curves for kaolinite, i l l i t e , sodium montmorillonite and calcium montmorillonite. Kerr and Kulp (1951, pp. 240-271) present 125 thermal curves of minerals with distinctive heating curves which are of considerable value as a re-ference i n the examination of a wide variety of materials. Several types of apparatus are i n use today, but a l l consist essentially of a furnace, a sample holder, a controller and a reoorder. At the Physical and Crystal Chemistry Laboratory of the Department of Mines, Ottawa, considerable experimental work has been carried out during the design and installation of suitable equipment. Two furnaces are used: one furnace i s wound with "Karthal" resistance wire permitting repeated use up to about 1100°C and the other i s wound with 80$ Pt: 20$ Ph., which w i l l allow temperatures up to 1700° i f necessary. Temperature control i s ob-- 160 -tained by a standard commercial Leeds and Northrup program controller. Rate of heating is controlled at 12°C per minute. The sample holder is made of palladium metal. The unknown mineral, a sample of approximately .5 gms, and the inert alumina are placed in two vertical one quarter inch holes. The differential couple is placed in two small horizontal holes which pene-trate the sample holes. Another horizontal hole equidistant from the differential couple holes carries the thermocouple which controls the heating rate and also records the temperature of the sample. The connections in the thermocouple are so arranged that the potentials oppose each other and as a result when no reaction takes place in the sample the potentials balance thus indicating that there is no temperature differential. Any heat effect in the sample causes an unbalance and this is picked up on a sensitive recording device. Consequently the plot is a straight line when no reaotion is taking place but peaks are recorded in one direction or the other, depending on heat effects, when reaction occurs. As the thermal curve is a differential function, i t depends only on those effects that do not occur simultaneously and equally in the specimen and the inert material. The recording equipment is made up of a sensitive 0-center Speedomax recorder which has a normal f u l l scale sensitivity of 2 millivolts. A special scale mulliplier and a Leeds and Northrup 0-centre preamplifier along with the Speedomax allow for a f u l l scale sensitivity of 500 micro-volts . Several tests of Bute Inlet sediments were made by the differential thermal method, but no clay minerals were found. It is generally accepted that for sediments which do not have appreciable percentages of clay minerals, the X-ray diffraction method is more effective in detecting minor amounts of these minerals than the differential thermal procedure. - 161 -Some workers in fact, believe the X-ray method to be more diagnostic and quantitative than the differential thermal in any clay mineral study. The fact that neither X-ray or differential thermal examination detected a clay mineral component in the Bute Inlet samples examined can be taken as an indication that these sediments, although fine-grained, contain at best only very minute amounts of clay minerals. Private communication from Dr. Parke A. Dickey. - 162 -PART VII Evaluation of Laboratory Data Uses of S t a t i s t i c a l Measures Once laboratory observations have been completed, information ob-tained must be organized i n such a manner as to permit ready interpretation and application to the solution of some particular problem. The progress made i n theoretical sedimentation becomes significant i n applied f i e l d s of geology when theoretical data i s translated into forms which may be used directly. In this interpretation procedure, graphical and s t a t i s t i c a l devices are of great assistance. The data of quantitative environmental studies of sedimentation lend themselves to presentation on contour type maps and surfaces and these i n turn afford an excellent means of evaluating the data gathered i n terms of the problem at hand. It i s well therefore to have in mind a classification of maps while data i s being gathered so that the most suitable method of presentation may be selected. Contour type (isopleth) maps of sedimentary data can be classified as follows. F i r s t , there are general regional maps, such as regional stratigraphical maps which show by gradations areas of lime, shale and sand, the data being expressed as lines of equal percentages of these three lit h o l o g i c a l types. Maps of particle properties have an important place in the study of recent sediments. These maps show the area variation of such measured attributes as size, shape, roundness, surface texture and orientation. Such particle maps may indicate not only average values of the particle attributes, but also a host of other s t a t i s t i c a l parameters. For each particle property there i s an average, a measure of spread (sorting), a measure of asymmetry (skewness), and a measure of peakedness - 163 -(kurtosis). Then there are maps of mass physical properties based on such aggregate properties as porosity, permeability, color, average density and thickness. Isopach maps are the most common i n this group. Maps of mass chemical properties can be drawn showing the variation of a given element or a compound. The geochemical gradients mentioned in connection with spectrographic analysis are suitable data for this type of map. Another variety of this map-type is used to show the amount and distribution of organic, radioactive and insoluble residue constituents. Maps of mineralo-gical properties constitute a f i f t h type. Heavy mineral data make suitable material for the preparation of this kind of contour map. The percentage of "heavies"j or the percentage of particular speciesj or ratios among various species, such as resistant to non-resistant, may yield information of value. S t i l l another type i s that of associated geological processes. Examples are maps of current distribution and velocity variations which may indicate relationships with sediment patterns, especially with respect to particle size data. A seventh type oould include biologio and paleonto-logic features. Maps showing the amount and character of fluids contained within sediments are also valuable: the fluids contained within the sediments constitute part of the sedimentary or post-depositional record, hence their importance. Such maps have particular use i n o i l - f i e l d work and can be used to show A.P.I, gravity of o i l and specific gravity. Maps of associated structures showing such features as bedding, cross-bedding, ripple-marks and concretions may be compiled. The group of maps of attribute combinations comprises many sub-types such as average particle size divided by thickness, or porosity as compared to sand thickness. These combination maps may bring contrasts or similarities among attributes into bolder r e l i e f than would the direct comparison of a series of individual maps. Thus there is a wide variety of map-types that may be used to show - 164- -sedimentary characteristics and many of these are particularly suitable for the presentation of recent marine sedimentary data. The compilation of such maps is part of the process of s t a t i s t i c a l analysis of sediments. The process of study of sediments, combining as i t does the collecting, classifying, presenting and analyzing of sedimentary data, i s i n i t s e l f a s t a t i s t i c a l procedure, and as such makes use of the facts which have been collected and classified on the basis of relative numbers or occurrence as a ground for induction and inference of general trends. The ultimate object of sedimentary petrography is to relate characteristics with environment; consequently the s t a t i s t i c a l method selected must be a means of examining areal variations i n terms of the underlying laws which control them. This implies the comparison of one sample with the next. The importance of a s t a t i s t i c a l approach i s evident when the problem presented i s that of evaluating grain size i n terms of the laws of transport. Here, individual particles may depart from the law of the average, due to unpredictable causes operating i n the environment; consequently probability considerations are required to evaluate the variations which may be attributed to chance. There are many points of view regarding the use of s t a t i s t i c a l procedures i n sedimentary studies, ranging from the extremes of complete rejection on the basis that the errors of sampling and analyses are so large that the data have l i t t l e quantitative significance, to the complete adoption of a l l s t a t i s t i c a l methods including such detailed analyses as can only be carried out with the aid of extremely complicated mathematical procedures. The viewpoint which appears to be most logical i s that of recognizing that s t a t i s t i c a l manipulation cannot create data but at the same time that by applying conventional s t a t i s t i c a l measures to sediments, the relation of the measures to the body of s t a t i s t i c a l theory can be - 165 -known. Thus a means can be provided of summarizing large amounts of infor-mation so that descriptions and comparisons can be greatly simplified, and so that environment analyses can be carried out using these descriptive measures. The purpose of this Part i s to i l l u s t r a t e , with reference to data obtained i n the laboratory examination of Bute Inlet sediments, the applicability of several graphical and s t a t i s t i c a l devices to the study of recent sediments. The Histogram, Simple Frequency and Cumulative Frequency Curves. The histogram i s widely used as a graphical device and has an appli-cation i n sedimentary studies, especially i n representing meohanical analyses. The advantage of the histogram i n mechanical analysis represen-tation i s that i t gives a good visual picture of grain-size distribution and of sorting and i s therefore suitable for demonstrating changes in these characteristics i n relation to spatial distribution. It has two limitations: for comparison work a l l graphs must be constructed on the same grade scale and must use the same grade limitsj and i t attempts to picture a continuous series of variables, which diff e r by infinitesimal amounts, as though these variables were divided into distinct classes by f i n i t e differences. In spite of these criticisms histogram presentation appears i n many sedimentary analyses reports. Figure I, C shows a series of histograms for 20 Bute Inlet samples, drawn to show the size distribution i n these sediments as determined by sieve and hydrometer analyses. The simple frequency curve can also be used for representing mechanical analysis data and although not quite as suitable for tracing - 166 -changes i n grade size by visual inspection, does recognize that variables change continuously throughout the size range. Like histograms, simple frequency curves must a l l be plotted on the basis of the same grade limits, i f they are to be used i n comparative studies. Figure I, A shows simple frequency curves for 20 Bute Inlet samples as a means of representing percentage mineral frequencies. The frequency percentages are plotted for the principal minerals: quartz, soda plagioclase, biotite, K-feldspar, calcic plagioclase and amphiboie. Figure I, B employs the simple frequency curve to represent size data i n the sand fraction for 20 samples. These graphical devices are a means of representing variations i n mineral frequencies due to varying sources of sediments, contamination, selective abrasion and selective transportation, A contamination effect results when a stream which i s carrying material gathered from a drainage basin characterized by certain rock-types i s later joined by streams which have flowed through a different l i t h o l o g i c a l terrain. Selective breakage and abrasion also account for diminutions of certain minerals and apparent increases of others. Grade sizes are not a l l equally affected and the per-centage of a given mineral species may either rise.or f a l l owing to such selective wear and elimination. These effects have taken place largely i n the streams before the sediments have been discharged into Bute Inlet. Once i n the fiord, sediments are affected by selective transportation and certain constituents lag behind owing to higher S.G., larger size, or high sphericity. Mineral particles of lower density smaller size and larger surface area may be oarried considerable distances from land. The histo-gram and the simple frequency curve afforded a means of reaching some con-clusions regarding the mineralogy of Bute Inlet sediments. These con-clusions are summarized i n Part V. Until the data gathered during sedimen-tary petrography investigations i s compiled and shown by such devices as - 167 -histogram or frequency curves, there is no way of getting an overall view of the mineralogy or of searching out significant mineralogical or textural changes. Description of sediments in terms of heavy minerals and the use of these minerals in correlation work can be applied to certain types of sedi-ments. Correlation attempts depend for their success on the recognition of a distinctive association of minerals, an unusual variety of a mineral or the relative abundance of certain constituents. Smithson (1939, pp. 292-309, 348, 360) illustrates the use of heavy minerals in correlation studies. Detailed studies of the heavy mineral content of Bute Inlet sediments is not a very practical approach to a description of these sediments because the sand-size fraction is very small and consequently only minute quantities of heavy minerals are to be found. Consequently no attempt was made to record the amounts of these constituents, other than amphibole, but identi-fications were made where particle size permitted. The cumulative frequency curve is of particular value in appraising mechanical analysis data. One advantage of this type of curve is that i t is practically independent of the grade scale used and Is therefore a more reliable index of the nature of the distribution of particles in sediments than a histogram or simple frequency curve can be. Curves drawn from hydrometer and sieve analyses information are shown in Figure 6. They are plotted on semi-logarithm scales because the ordinary coordinate scale gives undue prominence to the coarse end of the distribution and masks the distribution of the fines. Semi-logarithm plotting yields intervals on the abscissa scale for sieves of the Wentworth and Tyler series, which advance in mesh scale by the factor of the square root of 2. Although parameters were largely measured in mm., the Krumbein phi scale was also placed on the Figure to show the relation between the two grade scales and to make - 168 -provision for taking parameters based on that grade scale i f so desired. Krumbein devised this grade scale by replacing particle size i n mm. by i t s logarithm to the base 2, ar b i t r a r i l y selecting for the parameter phi the value of zero for the 1 mm. size and letting ascending values of phi corres-pond to descending magnitudes of grain diameter and vice versa. Median Diameter, Sorting and Skewness Coefficients Due to the fact that two sediments of different character may be represented by sim i l a r i l y shaped curves which d i f f e r only i n their position with respect to the two axes, several mathematical values can be taken from the cumulative curve which express the nature of the sediment better than do the curves themselves. Some of these mathematical measures are the median diameter, quartile diameters, arithmetrical quartile deviation, coefficient of sorting, arithmetrical quartile skewness, coefficient of geometrical quartile skewness, quartile kurtosis and various moment measures. One of the fundamental purposes of l i s t i n g sediment parameters, after curves have been drawn, i s to f a c i l i t a t e the comparison of sediment analyses and to aid i n the correlation between sediment types and their environment. From the above l i s t , i t i s seen that there i s a wide choice of procedures available for analyzing sedimentary data. Furthermore these may be based on either descriptive measures in the Krumbein: phi notation or descriptive parameters i n the millimeter notation. However i n the rapidly expanding f i e l d of sedimentation there appears to be a notable lack of standardization i n the matter of s t a t i s t i c a l expression; consequently comparisons of sedimentary environments are d i f f i c u l t to make when the results of investigations are expressed i n many different ways. In analyzing size data of Bute Inlet samples three of the most commonly used descriptive parameters i n the millimeter notation were em-ployed: median diameter, Trask's sorting quotient, and Trask's skewness - 169 -coefficient. Median diameter, M, is determined by noting the particle size at the intersection of the 50% line and the curve. The statistical con-stants formulated by Trask (1932, pp. 67-75) for sorting and skewness can be calculated from observations made of Ql and Q3> the 25% and 75% inter-section diameters. The sorting factor, So, which is a measure.of dimensional spread of the sediment size distribution, is computed by taking the square root of the quotient Q3/Q1 with the numerator always representing the coarser particles. The skewness coefficient, Sk, is the product of Ql and Q2 divided by the square of the median diameter, M. The log of the skewness (to base 10) is used in presenting the data. Using the conversion chart of Krumbein and Pettijohn (1938, p. 237, Figure 111), the values for this logarithmic function can be converted into phi units of quartile skewness. Table XV sets out the data obtained from the cumulative curves and the statistical constants derived from these data. Column 1 gives the sample number; column 2 shows the median diameter in mm.; column 3 gives the median diameter in phi units, as taken from the conversion scale at the bottom of Figure 6; columns 4 and 5 contain the 75% (03) and the 25% (Ql) quartiles; column 6 setB out the sorting coefficient, (So); in column 7 is given the logarithm of skewness to the base 10; from the data of column 7, the phi quartile skewness is obtained by using Krumbein and PettiJohn's con-version graph and the values so obtained, (SkgeO, are placed in column 8. Figure 12 shows a plot of sorting quotient against median diameter and, although only a small number of samples were analyzed, this figure indicates that the sediments of best sorting are of the coarsest size. Using Trask's criteria that a sorting quotient of less than 2.5 indicates well-sorted sediments, 3.0 normally-sorted, and 4.5 poorly-sorted, i t can be seen from column 6 of Table XV that samples 23, 22, 18, 14, 12 and 9 are - 170 -TABLE XV STATISTICAL BATA FROM CUMULATIVE CURVES, BUTE INLET SEDIMENTS* Sample Median Median Dia. Q J 3 Ql So. Log Sk Skq.0 No. Dia. Mm. Phi Units. Mm. Mm. 10 23 .022 5.5 .030 .012 1.58 -.131 .220 22 .018 5.8 .031 .005 2.4S -.328 .550 20 .010 6.5 .018 .002 3.00 -.444 .710 17 .014 6.1 .022 .003 2.79 -.770 1.30 18 .018 5.8 .032 .008 2.00 -.102 .180 16 .016 5.9 .080 ..004 4.48 -.079 -.14 27 .007 7.1 .015 .0015 3.16 -.337 .58 Hq. .095 3.2 .147 .040 1.91 -.193 .32 28 .002 8.8 .0096 .0006 4.09 .176 -.28 13A-1 .009 10.0 .017 .0026 2.55 -.264 . .45 12 .015 6.0q .04L .008 2.26 .161 -.26 11A .011 6.4 .030 .0025 3.47 -.208 . .34 11B .006 7.2 .012 .0015 2.83 -.302 .50 9 .011 6.4 .018 .003 2.45 -.342 .58 7 .006 7.2 .013 .0012 3.29 -.362 .60 6 .004 7.5 .014 .0008 4118 -.157 .25 3 .003 7 .9 .013 .0006 4.65 -.065 .10 2 .060 4.0 .500 .0025 14.10 -.461 .76 4 .0045 7.6 .012 .001 3.47 -.227 .39 1 .009 6.7 .022 .004 2.35 .037 -.061 - 171 -well-sorted sediments; 2, 3 and 16 are poorly-sorted; and the remainder approach the figure descriptive of average sorting. This column also shows that for the Bute Inlet samples analyzed, one sample-number 2-differs widely from the general rule for sediments that coarser sediments have better sorting than do finer sediments. Phi quartile skewness i n relation to median diameter i s shown i n Figure 13 from which i t can be concluded that skewness appears to be of l i t t l e genetic value for Bute Inlet sediments. However the values for skewness as shown i n column 8 are a l l positive except for samples 16, 28, 12 and 1; i.e., a l l but these four samples are skewed in the direction of the positive phi axis. When a curve i s symmetrical, skewness i s equal to unity, and the mode coincides with the median diameter. If the skewness i s greater than unity, the maximum sorting of the sediments l i e s on the fine side of the median diameter; i f i t is less than unity, on the coarser side. Skewness, which i s therefore a measure of the tendency of the size d i s t r i -bution to spread out on one side or the other of the average, may result i f a sediment showing symmetrical size distribution is later acted upon by a transporting agency which only removes a portion, or there may be a tendency for skewness to increase i n the direction of transport. No particular significance i s attached to the fact that the majority of Bute Inlet skewness values are positive because only 20 samples have been analyzed; however a record of this tendency is included as i t might with further i n -vestigation prove to be characteristic for fiord sediments. It i s interesting to note that the histograms of Figure 1, 0 confirm the results of the sorting factor data. Histograms such as those of sample numbers 23, 22, 18, 14, 12, 9 and 1 are representative of well-sorted sedi-ments because they have a maatimum, about which there i s a uniform > i o f-l <J 5.0 4.0 2,C <.[ oC60) K.oo?) % X Bl&ck ? { . 0 l l ) X >C3(.010) 1 , 6 . 22(o0lS) ^i-or SJs53, x o 0 x ( . 0 1 ° ) 9(.nilJ x 23(.o^} 17 (.01/,) 1 ) «? 16 24 32 40 I . i los Fro-, Usu-i v.1:* F i o r d . Fj;nj?3 H a n'Jlatioar.hjp betvreen orjar:ic r.^tter content , aoa-Xl-2 pcKiU c . n and modiiin dimeter of saupies. UI.VJ In le t J c d i m c i t s . 1 0 • t i 3 •M . 1 0 .0*. . 0 4 o 6 Figure LU. Relation, botwoon kedian ?'i&.*oter. and Sort-ing 7i*ctor, 3o«, 2U*-J Inlrt S^di'njnts. ra ft •r-i <!> 1 o 9 •H . © »7 I •6 3 X X K * * * X XX X X X * k • < .x • . 4 r>.2 -0- .2 .4 *o . .8 Ska> Figure 13. Skewneps vs. i"edi*jr: Diameter, Bute Inlet dodiiiients. - 172 -gradational reduction to zero i n either direction. The sorting quotients for these samples are a l l less than 2.5, also a measure of good sorting. Thus the graphical and mathematical descriptions of these samples are in agreement. Similarily for samples 16, 28, 6, 3 and 2, both histograms and sorting quotients are i n agreement as to poor sorting. The effectiveness of these two methods i s illustrated by comparison of the best and the poorest sorting, as seen for samples 23 (So. of 1.58) and 2 (So. of 14..10). The histogram of sample 23 shows good grouping about the size range 0.031 to 0.062 mm.; the histogram of sample 2 shows a size-spread across a large range, with no clearly defined maximum. The histogram and sorting data i l l u s t r a t e well that, although two of the better-sorted sediments were obtained near the head of the fi o r d , well sorted sediments are found at intervals down the length of the fiord} therefore the factor of sorting, as well as the average size of the sediments, must be considered i n terms of local conditions of currents, bottom topo-graphy and shoreline features. No general conclusions can be drawn about sediment distribution by simply relating size data to distance from the head of the i n l e t , where the main rivers enter. The sediments at shallow depths of 300 feet near the head of the i n l e t are somewhat coarser than those at 2000 foot depths near the mouth of the i n l e t , but there i s some variation i n texture and sorting within the fiord due to these varying conditions of currents, bottom topography and shoreline features. The inter-relationships of mediam diameter, sorting and skewness are used i n the study of ancient sediments i n order to build up a picture of • conditions under which sediments were transported and deposited. Inman (1949, PP* 51-77) presents some conclusions on the value of these c r i t e r i a . To complete the graphical analysis of Bute Inlet sediments, data from sieve and hydrometer tests have also been plotted on a t r i l i n e a r chart - 173 -(see Figure 14) set up to show the proportions of sand, s i l t and clay. As do the cumulative curves, this chart shows that the major portion of the Bute Inlet sediments lies in the s i l t range of size classification. A Statistical Comparison of MacKenzie River & Bute Inlet Sediments As mentioned in Part V under the heading of "Mechanical Analyses of the Sand Fraction", a sieve analysis was made of four MacKenzie River delta samples, the sieve analysis data being shown in Table V and the curves in Figure 3. The mineralogy of these samples is of l i t t l e significance in itself as i t is not tied in to any other geologioal observations, but i t is interesting to compare the mineral content of the samples with the mechanical analysis data. Samples 11 and 17 which are very similar in texture and sorting are also remarkable alike in mineralogical composition. Each 'sample consists of about 75% quartz, 5% potash feldspar and almost 20% amphibole, with minor amounts of magnetite, zircon and garnet and about 0.8% carbonates. Neither sample contains any mica. Sample 30, the finest-grained of the four, has 85% quartz, only 4% amphibole but 10% carbonates and 1% magnetite and zircon. Sample 35 has the poorest sorting and although being also high in quartz, about 80%, has a much larger content of magnetite than the, other samples, approximately 3%, and also some small shale frag-ments. The magnetite is concentrated in the fine fractions, the shale fragments in the coarse, and most of the 5% amphibole in the medium fractions. Thus, although a l l four samples are well-sorted and of somewhat the same general composition, the textural and sorting differences that do exist are an expression of mineralogical differences, and mineralogy and mechanical analyses reflect slightly different conditions ofvdeposition for these four sedimentary samples. Median diameters and sorting coefficients - 174 -are recorded on Figure 3. It will be noted that these river sediments are much coarser and somewhat better sorted than the sediments of Bute Inlet. The cumulative curves of this Figure and of Figure 6 demonstrate the difference in texture between sediments of a large river and those of a fiord. This data on the MacKenzie River delta sediments is included to show, by contrast, the fineness of the fiord sediments, and also to i l l u s -trate the fact that sediments of different environments can readily be compared by using graphical and statistical devices. A Trend in Statistical Analysis An indication of the trend towards more adequate and uniform statis-tical procedure in describing sedimentary data is the proposal of Inman (1951), who recommends the use of descriptive measures that are based on more rigorous statistical concepts than those now in use. Inman would use five parameters in the phi notation and compute them from the 5 percentile diameters obtained from cumulative size frequency curves. The parameters suggested are the median diameter, standard deviation, kurtosis and two measures of skewness. If the five descriptive measures are listed for a sediment, i t is possible to compute the five percentile diameters on which they are based and hence five significant points on the cumulative curve of the sediment. If such a procedure were taken into wide use, i t would be preferable for fundamental studies to systems devised for special projects, such as that proposed for use in Fraser River Model studies (Maartman, 1951) which is an adaptation of Rouse's method of plotting results on probability paper and using slopes of lines as a' measure of standard deviation. This adaptation only makes provision for three parameters and places emphasis on the central tendenoy of the curve. - 175 -In view of the number of statistical methods being currently devised for sedimentary studies, i t would seem to be preferable to use such standards as those f i r s t formulated by Trask until such time as a new standard, such as that proposed by Inman, is taken into general use, be-cause presentation of data in a manner not widely used limits the value of the work due to difficulties in making interpretations and comparisons. Notwithstanding the difficulties of getting representative samples for mechanical analyses (see Ritenhouse, 1944, pp. 20-25) and mineralogical studies, and the lack of uniformity in statistical practice, there is much information of value to be obtained from the histogram and the simple and cumulative frequency curves that wil l assist in an understanding of the processes of sedimentation. - 176 -PART VIII SUMMARY A Suggested Laboratory Schedule The study of recent and near-recent sediments involves many geologi-cal principles and requires the use of a wide variety of specialized f i e l d and laboratory techniques. The purpose of this particular study has been to inquire into some of these principles and to try to select the most suitable laboratory procedures for gathering information on the properties of recent marine sediments i n the light of such an inquiry. Reference has been made to other types of recent sediments investigations, such as those of s o i l mechanics, pedology and ceramics, i n order to il l u s t r a t e the applicability of fundamental laws of sedimentation to technological purposes. The laboratory work done during the course of this study centered on a small-scale investigation of some bottom samples and cores from Bute Inlet. From this laboratory work, a partial picture was obtained of the properties of Bute Inlet sediments and of their pattern of distribution with respect to the depositional environment. Some inkling was gained of the processes and patterns of this environment of deposition. A f u l l understanding of these two groups of information - sediment properties and environmental characteristics - plus details of the properties and distributional pattern of the products of post-depositional change may be said to constitute the three basic objectives of fundamental research i n recent sediments. This type of research has a direct application i n improving current methods of finding o i l and an indirect use i n a l l i n -vestigations concerned with unconsolidated sediments. Based on the laboratory work done i n this project, the following sequence of procedures i s suggested for the examination of recent marine - 177 -sediments. (See also Figure 15). F i r s t , a general description of the appearance, the main properties and the chief constituents of the sediments can be given. A preliminary appraisal i s conveniently done by making a separation on the superpanner or by drying a sample and examining i t under the binoculars. Color i s described by referring to the Munsell Color Chart and should be recorded for both wet and dry states of the sediments. Before further mass-property tests are commenced, the electrometric 'factors should be investigated. These include pH and Eh. Presumably temperature and salini t y would have been measured at the time the sample was taken. Other types of investigations which require early attention are organic matter determinations and bacteria examination. Although the latter i s not carried out in the geological laboratory, the data on organic matter and electrometric characteristics of sediments can only be f u l l y evaluated i n the ligh t of bacteriological data, and a l l three types of investigations are essential to an understanding of the processes of deposition. The water content of sediments should be measured as to amount and also tested as to Eh and pH. Furthermore for complete information, chemical analyses should be made of the water. These data are essential, especially where the sediments have a high clay mineral content, because the nature and volume of reactions between clays and various salts and water soluble organic constituents are controlling factors i n the i n i t i a l stages of deposition. Water data should be obtained soon after sampling. Essential, too, to the interpretation of depositional reactions i s a measure of the base exchange capacity. A long term program w i l l enable observations of base exchange and of water characteristics to be made several times a year, an essential procedure i n any fundamental study of SCHEDULE OF OPERATIONS FOR LABORATORY EXAMINATION OF RECENT SEDIMENTS Field Sample I Splitting i Preliminary pH Moisture Organic Calcium I Examination Eh Content Matter Carbonate Color Texture Superpanner, Binoculars I 1 I I 1 Stricture Fossils S.G. Porosity Chemical Rock Permeability Anal» Fragments Pl a s t i c i t y Shrinkage 1 Sand Fraction I Size Analysis - Sieves or Siltometer ! Isodynamic Separator Dispersion I 250 Mesh Sieve Magnetic Fraction I Non-magnetic Fraction Heavy Liquid Separation (Centrifuge) I Mineral and Micro-fossil Examination 1 : T I I Mounts Miners! Shape and Frequency Index Oils Analyses Roundness Analysis Thin Sections Binoculars Analyses Canada Balsam,-Bakelite Petrographic Staining Microscope X - ray n S i l t and Clay Fractions Size Analysis Hydrometer Pipette Centrifuge I Mineral and Trace Element Analyses Petrographic Microscope X - ray Spectrograph Electron Microscope Differential Thermal Analysis Staining Techniques Graphical and S t a t i s t i c a l Analyses Figure 15 . - 178 -depositional processes. Once these observations relating to electrometric, chemical and organic characteristics have been made, attention can be given to further examination of mass properties. Measurement of porosity, permeability, specific gravity,otexture and structure, pl a s t i c i t y , shrinkage, compaction, bonding strength, calcium carbonate content and radioactivity can be made on representative portions of the original sample. Chemical analyses for certain elements may be warranted. The next step i s the preparation and dispersion, without drying, of a 50-gram sample. Then separation of sand and s i l t - c l a y fractions i s made with the 250 mesh Tyler sievej the sand fraction i s dried and sized by sieving; the s i l t clay portion is sized by hydrometer, pipette or centrifuge methods. Fine-grained fractions of the s i l t - c l a y material are recovered by centrifuge or by decantation and are retained for clay mineral i d e n t i f i -cation by the employment of X-ray, the electron microscope, differential thermal analysis and staining techniques. Spectrochemical determinations of certain selected trace elements may provide information of value. The dried sand fraction i s sized by sieving or by use of the Puri siltometer. At this point a departure from standard procedure is suggested and the use of the isodynamic separator is recommended for the i n i t i a l separation of each size fraction into magnetic and non-magnetic groups. Further magnetic separation may be carried out i f desired. Heavy liquid separation can then be made on the non-magnetic material. It i s suggested that this emphasis on magnetic separation i n preference to heavy mineral separation be considered for each new project. For sediments which respond to magnetic methods the isodynamic procedure can be used as the principal method, to be supplemented where necessary by heavy liquid separation. The separates of the sized sand fraction are then sampled by use of some such - 179 -device as the microsplitter. Binocular examination i s carried out, within the limits of this instrument, and further detailed examination i s made with the petrographic microscope. Sand grains may be studied i n air index-oil or thin-section mounts for working out mineral identifications and fre-quencies. Surface textures and any outstanding physical characteristics of the several mineral species are noted. Calibration curves of index o i l s , as drawn from data obtained during Abbe refractometer calibrations, are of considerable assistance i n identifying mineral species and i n the quantitative estimation of amounts of major minerals, such as the various feldspars and quartz. Shape and roundness determinations for quartz can be made from camera lucida drawings and related computations or by direct com-parison with standard charts. Data on the sand fraction i s completed by compiling a record of f o s s i l and microfossil characteristics. Presentation of sedimentary data i s accomplished through the rise of such devices as isopleth maps, histograms, simple and cumulative frequency curves, t r i l i n e a r diagrams and distance-percentage graphs. S t a t i s t i c a l analyses might well be restricted to such expressions as median diameter, and sorting and skewness coefficients, which can be related to geologic factors. Some Characteristics of Bute Inlet Sediments Based on the results of laboratory examination, certain conclusions for 20 samples of Bute Inlet sediments may be stated. These sediments are predominantly s i l t s j the sand fraction does not exceed 5$, and the clay-size fraction has an average amount, for the 20 samples, of 23$. The mineralogy of the sand fraction, as detailed i n Table 10 and Figure IA, i s characterised by the principal minerals quartz, soda plagioclase, biotite, potash-feldspar and amphiboie (hornblende, tremolite and galucophane). Accessory minerals include pyroxene (principally augite), zircon, sphene, muscovite, - 180 -apatite, epidote, garnet, magnetite and wollastonite. Diatoms, foraminifera, sponges, and siliceous sponge spicules are of general distribution. Bryozoa, ostracods, calcareous algae and fragments of shell of the clam Mytilus are to be found in samples near the mouth of the fiord. Of the trace elements, the manganese content is of the order of 0.10$ and strontium, 0.5$. Magnesium is in the range of 1 to 1.5$. Carbonate content is well under 0.5$ for a l l samples but one. Organic matter ranges in amount from 0.55$ to 4.48$. pH values l i e in the range 7.0 to 7.9. Observations made of a number of other mass properties can be used to describe further the Bute Inlet sediments: moisture content, 40-50$; shrinkage limit 19 to 34; porosity, 37-56$; permeability, about 10 mill i -darcys; color in the dry state by the Munsell notation, predominantly light grey - 5Y 7/1• Sphericity in these sediments increases with particle size in each sample; weighted average sphericities range from 0.51 to 0.64. Average roundness value l i e within the limits 0.34 and 0.42. A l l except four of the sediment samples can be described as well-sorted. There is a direct relation between the sorting quotients and sample median diameters, the quotient decreasing and therefore the sorting improving with increase in grain size. There is no evident relationship between skewness and grain size. Textural variation within the fiord is not great; that which exists is related more closely to shore-line drainage features rather than to distance from the head of the inlet. The mineralogy of the samples can be correlated to a certain extent with drainage-basin geology and three subdivisions, based chiefly on the nature and amount of the sand fraction, are indicated for these fiord sediments. Although,approximately 23$ of the material examined is made up of particles less than 2 microns in size, the clay mineral content is too small - 181 -to be measured. These sediments may therefore best be described as "rock-flour" and are products of a land which i s covered to an extent of about 16$ by permanent snow and ice f i e l d s . A large-scale investigation of Bute Inlet sediments and an analysis of other oceanographic data obtained from this area would provide a basis for comparing conditions of sedimentation with those thought to exist during the formation of petroliferous source beds. Observations that have been made to date indicate that Bute Inlet sediments are not accumulating under conditions typical of source bed formation. ACKNOWLEDGMENTS The writer i s grateful to Dr. H, C. Gunning and members of the Department of Geology, University of Bri t i s h Columbia, for the privilege of making this study and for the generous help received. Particular acknowledgment i s made of the many constructive suggestions given by Dr. W. H. Mathews under whose direction the study was carried out. Dr. M. Y. 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