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Marine geology of upper Jervis Inlet 1970

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MARINE GEOLOGY OF UPPER JERVIS INLET by ROBERT DRUMMOND MACDONALD B.A.Sc. U n i v e r s i t y o f B r i t i s h Columbia 1965 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n the Department of Geology We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF A p r i l BRITISH COLUMBIA 1970 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my Depar tment o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Depa r tment The U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8, Canada Date ABSTRACT Manganese-iron oxide c o n c r e t i o n s are p r e s e n t l y forming on P a t r i c k S i l l i n upper J e r v i s I n l e t . The marine geology o f P a t r i c k S i l l and the a d j o i n i n g b a s i n s (Queen's Reach and P r i n c e s s Royal Reach) was s t u d i e d t o d e f i n e the environment i n which the con- c r e t i o n s form. The r i v e r a t the i n l e t head i s the p r i n c i p a l source o f sediment to the upper b a s i n . The average g r a i n s i z e o f s u r f i c i a l bottom sediments w i t h i n t h i s b a s i n decreases u n i f o r m l y w i t h d i s t a n c e from the source. P a t r i c k S i l l s eparates the upper from the lower b a s i n . The sediment d i s t r i b u t i o n p a t t e r n w i t h i n the lower b a s i n d i f f e r s markedly from the upper b a s i n as t h e r e i s no dominant source o f m a t e r i a l but r a t h e r many l o c a l i z e d s ources. Abundant shallow marine f a u n a l remains recovered i n deep water sediment samples i n d i c a t e t h a t sediments d e p o s i t e d as d e l t a s o f f r i v e r and stream mouths p e r i o d i c a l l y slump t o the b a s i n f l o o r s . G e o l o g i c and o p t i c a l t u r b i d i t y i n f o r m a t i o n f o r the upper b a s i n can b e s t be e x p l a i n e d by slump- i n g from the d e l t a at the i n l e t head w i t h the i n i t i a t i o n o f t u r b i d i t y or d e n s i t y c u r r e n t s . P a t r i c k S i l l appears t o c r e a t e a downstream b a r r i e r t o t h i s flow. The mineralogy o f the bottom sediments i n d i c a t e s d e r i v a t i o n from a g r a n i t i c t e r r a i n . I f t h i s i s so, the sediments p r e s e n t l y b e i n g d e p o s i t e d i n both b a s i n s are reworked g l a c i a l m a t e r i a l s i n i t i a l l y d e r i v e d by g l a c i a l a c t i o n o u t s i d e the present watershed. Upper J e r v i s I n l e t i s mapped as l y i n g w i t h i n a r o o f pendant o f p r e - b a t h o l i t h i c rocks, p r i n c i p a l l y s l a t e s . P a t r i c k S i l l i s thought t o be a bedrock f e a t u r e mantled w i t h P l e i s t o c e n e g l a c i a l m a t e r i a l . The accumulation r a t e o f r e c e n t sediments on the s i l l i s low e s p e c i a l l y i n the V-notch or medial d e p r e s s i o n . The manganese-iron oxide c o n c r e t i o n s are forming w i t h i n the d e p r e s s i o n and a p p a r e n t l y nowhere e l s e i n the study a r e a . A l s o forming w i t h i n the d e p r e s s i o n are c r u s t s of i r o n oxide and what are t e n t a t i v e l y i d e n t i f i e d as g l a u c o n i t e - m o n t m o r i l l o n o i d p e l l e t s . The c o n c r e t i o n s are thought t o form by p r e c i p i t a t i o n o f manganese-iron oxides on pebbles and cobbles l y i n g a t the sediment water i n t e r f a c e . The oxide m a t e r i a l s are mobile i n the r e d u c i n g environment o f the u n d e r l y i n g c l a y e y - sand sediment but p r e c i p i t a t e on c o n t a c t w i t h the i i i oxygenating environment o f the J u r f i c i a l sediments. The i r o n c r u s t s are thought to be forming on exten- s i v e rocky s u r f a c e s above the sediment water i n t e r - f a c e . The o v e r a l l appearance and evidence of r a p i d formation o f the c r u s t s suggests they formed from a g e l i n sea water. Reserves o f manganese-iron c o n c r e t i o n s on P a t r i c k S i l l were estimated to be 117 m e t r i c tons. Other d e p o s i t s o f c o n c r e t i o n s have r e c e n t l y bean found i n other i n l e t s and i n the S t r a i t o f Georgia but, t o date, the extent o f these has not been determined. i v Table o f Contents A b s t r a c t Page i Chapter 1 I n t r o d u c t i o n i I H i s t o r y and Purpose o f the Study I I L o c a t i o n and P h y s i c a l S e t t i n g I I I P revious Work IV F i e l d Work and Acknowledgments Chapter 2 Geologic H i s t o r y and Regional Geology 9 I G e o l o g i c H i s t o r y o f Southwestern B r i t i s h Columbia II O r i g i n o f F j o r d s I I I R egional Geology Chapter 3 Methods o f Study 19 I F i e l d Methods 1. P o s i t i o n i n g 2. Sample C o l l e c t i o n 3„ Photography 4„ Echo Sounding and Continuous Seismic P r o f i l i n g I I Laboratory Methods 1. G r a i n S i z e D i s t r i b u t i o n i n Sediments 2„ Mineralogy o f Sediments 3„ G r a v i t y Core Analyses 4= Composition, S t r u c t u r e and Abundance of Manganese-Iron C o n c r e t i o n s V Page Chapter 4 Oceanography 31 I Bathymetry I I Temperature and S a l i n i t y I I I Oxygen Content and C i r c u l a t i o n IV T i d e s V O p t i c a l T u r b i d i t y Chapter 5 B a s i n S t r u c t u r e and Sediment Thickness 41 Chapter 6 Sediments 48 I Colour I I T o t a l Carbon Content I I I Free I r o n Content IV P a r t i c l e Morphology V Mineralogy 1„ Granule and Larger S i z e M a t e r i a l 2. Sand S i z e M a t e r i a l 3. C l a y S i z e M a t e r i a l VI G r a i n S i z e D i s t r i b u t i o n V II C h a r a c t e r i s t i c s w i t h Depth Chapter 7 Sedimentation i n J e r v i s I n l e t -\12 Chapter 8 A u t h i g e n i c M i n e r a l s 116 I Manganese C o n c r e t i o n s 1. Source Area 2, Age and Growth Rates 3„ S t r u c t u r e 4„ Chemical Composition 5. Mineralogy 6. Formation o f C o n c r e t i o n s 7. Abundance and Value II I r o n C r u s t s I I I G l a u c o n i t e - M o n t m o r i l l o n o i d P e l l e t s IV D i s c u s s i o n V E x p l o r a t i o n L i s t o f Tables Time S t r a t i g r a p h i c U n i t s f o r P l e i s t o c e n e o f Southwestern B.C. Table o f Map U n i t s M i n e r a l Abundances i n F i n e Sand F r a c t i o n jjDOlj Peaks ( i n Angstroms) o f M i n e r a l s i n Clay S i z e F r a c t i o n R e l a t i v e Abundances of Clay M i n e r a l Species Chemical A n a l y s i s o f J e r v i s I n l e t C o n c r e t i o n s Comparison of Elemental Analyses o f Manganese C o n c r e t i o n s v i i L i s t o f F i g u r e s Pag F i g u r e 1 L o c a t i o n Map-showing upper J e r v i s 2 I n l e t study area 2 Middle and upper J e r v i s I n l e t - 16 showing geology and drainage p a t t e r n 3 Sample S t a t i o n L o c a t i o n s - ( i n pocket) 4 Sampling Equipment 20 a) P e t t e r s s e n grab sampler b) Underwater camera c) Phleger c o r e r 5 Procedure f o r Sample A n a l y s i s 26 6 Bathymetry of upper J e r v i s I n l e t - ( i n pocket) 7 Transverse S e c t i o n s o f upper 33 J e r v i s I n l e t 8 Average V e r t i c a l P r o f i l e o f Tempera- 34 t u r e and S a l i n i t y - J e r v i s I n l e t 9 Water C i r c u l a t i o n as I n d i c a t e d by 37 L o n g i t u d i n a l P r o f i l e s 10 O p t i c a l T u r b i d i t y along J e r v i s I n l e t 39 11 Continuous Seismic P r o f i l e along 43 upper J e r v i s I n l e t 12 C l a s s i f i c a t i o n o f J e r v i s I n l e t 49 Sediments 13 G r a i n S i z e D i s t r i b u t i o n along A x i s 51 o f upper J e r v i s I n l e t 14 T o t a l Carbon Content o f Sediments (In pocket) 15 Clay S i z e P a r t i c l e and T o t a l Carbon 54 Content Along Axis of Upper J e r v i s I n l e t 16 I r o n E x t r a c t e d During Sample 59 P r e p a r a t i o n f o r X-ray A n a l y s i s . v i i i Page F i g u r e 17 Microphotographs of Sand Grains 62 a) S t a t i o n J-101 b) S t a t i o n J-101 c) S t a t i o n J-110 18 Microphotographs of Sand Grains 63 a),b) S t a t i o n J-126 c),d) S t a t i o n J-19-67 19 M i n e r a l D i s t r i b u t i o n along A x i s o f 74 upper J e r v i s I n l e t 20 Sediment Type D i s t r i b u t i o n ( i n pocket) 21 Clay S i z e P a r t i c l e D i s t r i b u t i o n ( i n pocket) 22 Mean and Standard D e v i a t i o n o f 87 G r a i n S i z e along A x i s o f upper J e r v i s I n l e t 23 K u r t o s i s a nd Skewness Parameters 88 along A x i s of upper J e r v i s I n l e t 24 L o n g i t u d i n a l P r o f i l e o f Queen's 90 Reach - Cumulative and Frequency Curves 25 Transverse P r o f i l e s o f Queen's 92 Reacth - Cumulative and Frequency Curves 26 Bottom Photographs - S t a t i o n J-126 93 27 Bottom Photographs - S t a t i o n J-126 94 28 L o n g i t u d i n a l P r o f i l e o f lower 96 Queen's Reach and upper P r i n c e s s Royal Reach - Cumulative and Frequency Curves 29 Bottom Photographs - S t a t i o n J-19-67 98 30 Bottom Photographs - S t a t i o n J-19-67 99 i x Page F i g u r e 31 Transverse P r o f i l e o f Queen's 101 Reach (over P a t r i c k S i l l ) - Cumulative and Frequency Curves 32 L o n g i t u d i n a l P r o f i l e o f P r i n c e s s 103 Royal Reach - Cumulative and Frequency Curves 33 Transverse P r o f i l e o f P r i n c e s s 104 Royal Reach - Cumulative and Frequency Curves 34 Bottom Photographs •- S t a t i o n J-160 106 35 Bottom Photographs - S t a t i o n J-160 107 36 G r a v i t y Cores from J e r v i s I n l e t 109 37 Bathymetry o f P a t r i c k S i l l ( i n pocket) 38 Bottom Photographs - S t a t i o n J-19-67 118 C o n c r e t i o n L o c a l i t y 39 Bottom Photographs - S t a t i o n J-19-67 119 C o n c r e t i o n L o c a l i t y 40 Examples o f C o n c r e t i o n s .122 a) Side View of D i s c o i d a l V a r i e t y b) S i l i c e o u s Sponge on S p h e r o i d a l V a r i e t y c) Coalescence o f two S p h e r o i d a l C o n c r e t i o n s 41 Cross S e c t i o n s o f Manganese 124 C o n c r e t i o n s 42 Cross S e c t i o n s o f Manganese 125 Co n c r e t i o n s 43 Manganese Con c r e t i o n s 135 a) Recovery i n P e t t e r s s e n Grab Sampler b) Dens i t y o f Occurrence c) L a r g e s t Specimen Recovered 44 Iron C r u s t s from P a t r i c k S i l l 138 1 CHAPTER 1 INTRODUCTION 1 - H i s t o r y and Purpose o f the Study L i t t l e work has been done on the marine geology of B r i t i s h Columbia i n l e t s . Sediment s t u d i e s have been made i n Bute I n l e t (Toombs .1956), Saanich I n l e t (Gucleur and Gross 1964), and Howe Sound (Murray and R i c k e r — u n p u b l i s h e d report)„ A se d i m e n t o l o g i c survey o f J e r v i s I n l e t was undertaken i n May, 1966 ^I.O.U.B.C. C r u i s e 66/12) to o b t a i n i n f o r m a t i o n f o r comparison w i t h sediment data from Howe Sound. Systematic sampling o f upper J e r v i s I n l e t r e v e a l e d a l o c a l i z e d d e p o s i t of manganese-iron c o n c r e t i o n s , or nodules, on a sub- marine s i l l ( P a t r i c k S i l l ) . Thereupon, a more i n t e n s i v e study o f P a t r i c k S i l l and adjacent b a s i n s of upper J e r v i s I n l e t was conducted. Chemical s t u d i e s o f the c o n c r e t i o n s , the i n t e r - s t i t i a l water o f the sediments, and the water column are b e i n g made by Dr. E. V. G r i l l o f the I n s t i t u t e of Oceanography a t the U n i v e r s i t y o f B r i t i s h Columbia. A study o f a l l the oceanographic aspects o f the upper J e r v i s I n l e t system may l e a d t o a b e t t e r understanding o f the formation o f manganese con- c r e t i o n s i n shallow c o a s t a l waters.  3 IT.„ L o c a t i o n and P h y s i c a l S e t t i n g J e r v i s I n l e t i s l o c a t e d i n the n o r t h w e s t e r l y t r e n d i n g P a c i f i c Range o f the Coast Mountains. The mouth of the i n l e t l i e s approximately 46 n a u t i c a l m i l e s (85 k i l o m e t e r s ) west-northwest o f Vancouver, B r i t i s h Columbia, on the e a s t e r n margin o f the S t r a i t o f Georgia. The i n l e t i s 48 n a u t i c a l m i l e s (89 k i l o m e t e r s ) l o n g and the width averages 1.7 (3.2 k i l o m e t e r s ) and seldom exceeds 2.5 n a u t i c a l m i l e s (4.6 k i l o m e t e r s ) . The study area ( F i g u r e 1) encompasses the n o r t h e r n or upper p a r t of the i n l e t which i s d i v i d e d i n t o two l e g s or reaches by a r i g h t - a n g l e change i n s t r i k e of the a x i s . Queen's Reach i s uppermost and has a n o r t h - w e s t e r l y t r e n d w h i l e P r i n c e s s Royal Reach trends t o the n o r t h - e a s t . P r i n c e s s L o u i s a I n l e t , which opens i n t o Queen 's Reach, was not i n c l u d e d i n the study. P a t r i c k S i l l l i e s p e r p e n d i c u l a r t o the a x i s o f Queen's Reach at the p o i n t where Queen's Reach tu r n s i n t o P r i n c e s s Royal Reach. The manganese c o n c r e t i o n s occur on the southern f l a n k o f P a t r i c k S i l l a t 50°06.2' north l a t i t u d e and 123°47.8' west l o n g i t u d e . 4 Access to the area i s by boat or a i r c r a f t o n l y . J e r v i s I n l e t i s a g l a c i a l l y m o d i f i e d P l i o c e n e r i v e r v a l l e y which was invaded by the sea w i t h the waning of the P l e i s t o c e n e i c e sheet. The mountains surrounding the i n l e t tower t o 6,000 t o 8,000 f e e t (1800 t o 2200 meters) above sea l e v e l . Steep moun- t a i n s i d e s d i p a t angles averaging 30° t o 35° t o the water's edge and disappear w i t h no change of s l o p e . Deep s t r i a t i o n s on rock s u r f a c e s , mountain s i d e s too steep and p o l i s h e d t o t r a p s o i l t o support v e g e t a t i o n , and hanging v a l l e y s a l l i n d i c a t e e x t e n s i v e g l a c i a t i o n . The watershed area of upper J e r v i s I n l e t i s s m a l l , and many of the streams are i n t e r m i t t e n t . Queen's Reach and P r i n c e s s Royal Reach have water- shed areas of 27 3 and 157 square m i l e s (855 and 523 square k i l o m e t e r s ) r e s p e c t i v e l y . U n l i k e the m a j o r i t y of long i n l e t s , the r u n - o f f i n t o J e r v i s f o l l o w s the c o a s t a l r a i n f a l l p a t t e r n c l o s e l y , i . e . above average i n the s p r i n g and w i n t e r months and below average d u r i n g J u l y through September. T h i s i s due t o the absence o f l a r g e , permanent snow- f i e l d s w i t h i n the watershed t o s t o r e p r e c i p i t a t i o n . 5 The mean annual f r e s h water d i s c h a r g e i n t o J e r v i s I n l e t i s 236 c u b i c yards (180 c u b i c meters) per second. Howe Sound, which has a l e n g t h o f 23 n a u t i c a l m i l e s (42 k i l o m e t e r s ) , r e c e i v e s a mean annual d i s c h a r g e o f 630 c u b i c yards (480 c u b i c meters) per second. ( T r i t e s 1955). The average r a i n f a l l f o r southern i n l e t s i s estimated t o be 60 t o 100 inches (150 to 250 c e n t i m e t e r s ) a n n u a l l y at lower e l e v a t i o n s (B.C. A t l a s o f Resources,1956). However, w i t h a l t i t u d e , the amount o f p r e c i p i t a t i o n can i n c r e a s e t o 100 t o 150 inches (250 t o 380 cent i m e t e r s ) a n n u a l l y , e s p e c i a l l y towards the heads o f the i n l e t s . The i n l e t s funnel moist P a c i f i c a i r i n l a n d u n t i l , a t the head, t h i s a i r i s f o r c e d t o r i s e a b r u p t l y . About 10 to 15 per cent of p r e c i p i - t a t i o n f a l l s as snow. The mean monthly temperature a t the heads o f f j o r d s a long the west co a s t ranges from 20° to 25°F (-7°to -4°C) i n January, t o 38° t o 62°F (3°to 17°C) i n J u l y . On a d a i l y b a s i s , the mean maximum temperature i s 70° to 75°F (21° to 24°C). The average minimum temperature and the number o f f r o s t - f r e e days i n c r e a s e from the heads t o the mouths o f the i n l e t s (3„C.Atlas o f Resources, 1956). 6 With some exc e p t i o n s , the mountain slopes are covered w i t h v e g e t a t i o n t o an e l e v a t i o n o f a p p r o x i - mately 4600 f e e t (1400 meters). T h i s e l e v a t i o n does not repr e s e n t the t r u e t r e e l i n e , but r e f l e c t s a general l a c k o f s o i l at h i g h e r e l e v a t i o n s . The lower, v e g e t a t e d areas are c l a s s i f i e d as Coast F o r e s t b i o t i c r e g i o n . C h a r a c t e r i s t i c are e x t e n s i v e stands o f s i t k a spruce, r e d and y e l l o w cedar, f i r , western and mountain hemlock, and western white p i n e . These stands o f timber support many small l o g g i n g o p e r a t i o n s a l o n g the l e n g t h o f the i n l e t . T y p i c a l o f the Coast F o r e s t r e g i o n i s a dense underbrush o f maple, a l d e r , f e r n s , s a l a l , d e v i l ' s c l u b , h u c k l e b e r r y , salmonberry and t h i m b l e b e r r y . With i n c r e a s e i n e l e v a t i o n , the Coast F o r e s t g i v e s way t o the Subalpine F o r e s t b i o t i c r e g i o n . A l p i n e v a r i e t i e s o f spruce, f i r , and pine i n open stands and a matting o f b l u e b e r r y and heather t y p i f y t h i s r e g i o n . I I I . Previous Work P r i o r s e d i m e n t o l o g i c work i n J e r v i s I n l e t has been done only on a reconnaissance b a s i s as p a r t o f an o v e r a l l study o f the B„ C. c o a s t l i n e ( P i c k a r d , 1956), and the c o n t i n e n t a l s h e l f (Cockbain 1963). More d e t a i l e d g e o l o g i c s t u d i e s have been made i n 7 Bute I n l e t (Toombs 1956), Saanich I n l e t (Gucleur and Gross 1964) and Howe Sound (Murray and R i c k e r - unpublished)„ The s u r f i c i a l geology o f the upper J e r v i s I n l e t area was mapped on a reconnaissance b a s i s by LeRoy (1908). S i n c e then no f u r t h e r work has been p u b l i s h e d f o r t h i s area. Bacon (1957) des- c r i b e d the geology of the lower J e r v i s I n l e t a r ea. The c o a s t mapping p r o j e c t o f the G e o l o g i c a l Survey o f Canada, which i s p r e s e n t l y underway, w i l l g i v e the f i r s t u n i f i e d map o f the geology o f J e r v i s I n l e t . The p h y s i c a l oceanography of J e r v i s I n l e t has been s t u d i e d by many workers. P i c k a r d (1961) d e s c r i b e d and c l a s s i f i e d the i n l e t s o f the B.C. co a s t and presented o b s e r v a t i o n s o f o p t i c a l t u r - b i d i t y ( P i c k a r d and Giovando 1960). L a z i e r (1963) s t u d i e d J e r v i s I n l e t as an example o f a deep s i l l e d i n l e t and d e s c r i b e d a c i r c u l a t i o n o f unknown p e r i o d . IV. F i e l d Work and Acknowledgments F i e l d work was c a r r i e d out from the v e s s e l s C.S.S.Ehkoli and C.S.S.Vector of the Department o f Energy, Mines and Resources o f the F e d e r a l Govern- ment. The a s s i s t a n c e o f the o f f i c e r s and crew o f 8 these v e s s e l s was i n v a l u a b l e . D e t a i l e d bathymetric c h a r t s ( f i e l d sheets) o f the study area were generously s u p p l i e d by the Canadian Hydrographic S e r v i c e . F i n a n c i a l support was g r a t e f u l l y r e c e i v e d from the Dean's Research Fund o f the U n i v e r s i t y o f B r i t i s h Columbia, N a t i o n a l Research C o u n c i l o f Canada, G e o l o g i c a l Survey o f Canada (Contract EMR-63-IU), S p e c i a l P r o j e c t s D i v i s i o n o f Eear Creek Mining Company and the I n t e r n a t i o n a l N i c k e l Company o f Canada. Dr. J . W. Murray o f the Department of Geology at the U n i v e r s i t y o f B r i t i s h Columbia was the s u p e r v i s o r of t h i s work. CHAPTER 2 y GEOLOGIC HISTORY AND REGIONAL GEOLOGY I o Geologic H i s t o r y o f Southwestern B.C. E a r l y J u r a s s i c marked the b e g i n n i n g o f t e c t o n i c events which were t o u l t i m a t e l y form the I n s u l a r and Coast Mountain r e g i o n . T h i s orogenic episode, which was t o continue i n stages t o m i d - T e r t i a r y t i m e , i n v o l v e d a l a t e P a l e o z o i c e u g e o s y n c l i n a l - l i k e s u c c e s s i o n -®f s e d i - mentary and submarine v o l c a n i c r o c k s . Intense f o l d i n g , metamorphism and u p l i f t were accompanied by v o l c a n i s m and the development of l a r g e p l u t o n i c masses. Success- i v e stages o f t e c t o n i s m f o l l o w e d by e r o s i o n removed much o f the rock cover from the b a t h o l i t h i c c o r e s . The d e r i v e d sediments were d e p o s i t e d i n f l a n k i n g b a s i n s under marine and b r a c k i s h c o n d i t i o n s . The r e s u l t i n g l a n d s u r f a c e was a p e n e p l a i n o f low r e l i e f and average e l e v a t i o n o f 900 t o 1200 f e e t (270 t o 370 meters)be.low the present average. (Holland, 1964). D i f f e r e n t i a l u p l i f t o f t h i s e r c a i o n su-r-Jacc. o c c u r r e d d u r i n g e a r l y T e r t i a r y w i t h g r e a t e s t movement along two main axes of i n t r u s i o n . S e p a r a t i n g these axes, now the I n s u l a r and Coast Mountains, was a trough now cor r e s p o n d i n g t o the S t r a i t o f Georgia. Sediments d e r v i e d from f u r t h e r e r o s i o n o f re j u v e n a t e d areas were d e p o s i t e d i n t h i s C o a s t a l Trough along w i t h l a v a s and fragmental prod- ucts o f r e g i o n a l v o l c a n i s m . E r o s i o n c o n t i n u e d through the middle P l i o c e n e and f u r t h e r unroofed the g r a n i t i c 10 cores o f the u p l i f t e d areas. The l a n d s u r f a c e was reduced to one of low to moderate r e l i e f , co- e x t e n s i v e w i t h a s i m i l a r s u r f a c e w i t h a r e l i e f o f 1500 t o 2000 f e e t (460 to 610 meters) i n C e n t r a l B r i t i s h Columbia. (Holland, 1964). Late P l i o c e n e time marked the advent o f renewed d i f f e r e n t i a l u p l i f t along the p r e v i o u s l y a c t i v e axes r e s u l t i n g i n r e j u v e n a t i o n o f the e r o s i v e power o f a l l the streams. A t r a n s v e r s e upwarping d i v i d e d the c o a s t a l trough i n t o the Hecate Depression t o the north, and the Georgia Depression t o the south. The l a t e T e r t i a r y e r o s i o n s u r f a c e was deeply d i s s e c t e d and p a r t i a l l y t o almost completely d e s t r o y e d . The present topography i s e s s e n t i a l l y t h a t of the l a t e P l i o c e n e , c o n s i d e r a b l y m o d i f i e d by P l e i s t o c e n e g l a c i a t i o n s . During P l e i s t o c e n e time, southwestern B.C. was e x t e n s i v e l y g l a c i a t e d by c i r q u e , v a l l e y , and c o n t i n - e n t a l g l a c i e r s . L i k e the t e c t o n i c h i s t o r y o f the area, the g l a c i a l h i s t o r y i s very complex. S t u d i e s i n d i c a t e a t l e a s t two major C o r d i l l e r a n i c e sheet g l a c i a t i o n s separated by an i n t e r g l a c i a l stage. Some p e r i p h e r a l areas may have been s u b j e c t t o t h r e e or more major i c e advances. The sequence of major P l e i - stocene events i n southwestern B„C. i s g i v e n below. Table I. Time S t r a t i g r a p h i c U n i t s f o r P l e i s t o c e n e of Southwestern B.C. ., ( a f t e r Armstrong et a l , 1965) 1) Salmon Springs G l a c i a t i o n >̂ 37,000 years B.P. 11 Olympia I n t e r g l a c i a t i o n <24, 500 y 15,000 37,-000 years B . P . During t h i s p e r i o d , i c e was absent from the lowlands of southwestern B.C. This g l a c i a t i o n i s probably the r e g i o n a l e quivalent of the Wisconsin G l a c i a t i o n of the mid-western United S t a t e s . a) Evans Creek Stade 17,000 - 25,000 years B: By d e f i n i t i o n , during t h i s p e r i o d , l a r g e a l p i n e g l a c i e r s formed and reached t h e i r maximum extent. In B r i t i s h Columbia, expansion of the g l a c i e r s apparently r e s u l t e d i n ice-sheet formation. b) Vashon Stade 13,000 - <21,000 By d e f i n i t i o n , the Vashon i s the l a s t major c l i m a t i c episode during which d r i f t was deposited by c o n t i n e n t a l i c e o r i g i n a - t i n g i n B r i t i s h Columbia, and occupying the lowlands of southwestern B.C. and northwestern Washington. c) Everson Interstade 11,000 - 13,500 years B This p e r i o d began w i t h the i n v a s i o n of the lowlands by the sea, and ended w i t h e i t h e r the advance of the Surnas i c e sheet or, the withdrawal of the sea and the d i s - appearance of the f l o a t i n g i c e . d) Surnas Stade 9,500 - 11,000 years B.P A c l i m a t i c episode during f i n a l stages of emergence of the Fraser Lowland when a v a l l e y g l a c i e r occupied the eastern part of the lowland. This g l a c i e r may have been only a l o c a l advance of the C o r d i l l e r a n i c e sheet. Fraser G l a c i a t i o n approx. 9, 500 -)>15,000 \25, 000 years B.P. 1-2 The v a l l e y g l a c i e r s widened and deepened trunk v a l l e y s t o a U-shaped c r o s s - s e c t i o n l e a v i n g t r u n c a t e d spurs, hanging v a l l e y s and scoured rock s u r f a c e s . A r e s u l t , perhaps not immediately e v i d e n t , was the over-deepening o f many of the v a l l e y s . For example, the maximum depth i n J e r v i s I n l e t i s 385 fathoms (7 05 meters) and occurs about 10 n a u t i c a l m i l e s (18 k i l o m e t e r s ) from the mouth, j u s t n o r t h o f Nelson I s l a n d . T h i s depth exceeds by 178 fathoms (326 meters), the maximum depth i n the S t r a i t o f Georgia. The v a l l e y g l a c i e r s which flowed i n t o the S t r a i t of Georgia c o a l e s c e d and flowed south and southeast down the S t r a i t then southwest to west ac r o s s the end of Vancouver I s l a n d . The i c e sheet which accumulated d u r i n g the Vashon a t t a i n e d an estimated t h i c k n e s s of from 5,000 t o 8,000 f e e t (1500 to 2400 meters). The weight o f the i c e sheet depressed the l a n d s u r f a c e w i t h r e s p e c t t o sea l e v e l . The net e f f e c t on the c r u s t o f unloading, due to the waning o f the i c e sheet, was the emergence of the l a n d s u r f a c e . The h e i g h t o f emergence, as measured from r a i s e d beach d e p o s i t s , i n the v i c i n i t y o f the mouth of J e r v i s I n l e t was 424 f e e t (129 meters) at Texada I s l a n d 13 and 500 f e e t (152 meters) at Campbell R i v e r . (Holland,1964). With the r e t r e a t of the C o r d i l l - eran i c e sheet, the h e a v i l y scoured and probably n e a r l y sediment-free i n l e t s became d e p o s i t i o n a l b a s i n s f o r g l a c i a l and g l a c i o m a r i n e sediments. I I . O r i g i n a l of F j o r d s The s t r u c t u r a l p a t t e r n of the B. C. c o a s t l i n e has two components—one dominant and forming a c r u d e l y r e c t a n g u l a r network i n the north-west and n o r t h - e a s t d i r e c t i o n s , and the other s u b o r d i n a t e i n the n o r t h and e a s t d i r e c t i o n s ( P e a c o c k 1935). The former i s concordant w i t h the north-westward t r e n d i n g g r a i n o f the c o a s t l i n e and i s thought t o have o r i g i n a t e d from J u r a s s i c t e c t o n i s m . The sub- o r d i n a t e t r e n d i s thought t o have r e s u l t e d from e a r l y T e r t i a r y t e c t o n i s m (Peacock 1935). A m a j o r i t y o f the i n l e t s have abrupt h i g h angle changes i n s t r i k e o f t h e i r axes-a f e a t u r e e x p l a i n a b l e by s t r u c t u r a l l y c o n t r o l l e d f l u v i a l e r o s i o n . Rejuvenation of the e a r l i e r P l i o c e n e e r o s i o n s u r f a c e d u r i n g the l a t e P l i o c e n e c r e a t e d a deeply d i s s e c t e d and immature topography b e f o r e P l e i s t o c e n e g l a c i a t i o n s . Thus f j o r d s are the drowned lower p a r t s of immature v a l l e y s developed by f l u v i a l e r o s i o n and m o d i f i e d by i n t e n s e g l a c i a l 14 a c t i o n (Peacock, 1935). C h a r a c t e r i s t i c o f f j o r d s i s e x t e n s i v e over- deepening and gen e r a l presence o f one or more t h r e s h o l d s or s i l l s along t h e i r l e n g t h . Over- deepening i s a p p a r e n t l y r e l a t e d t o g l a c i a l e r o s i o n but the o r i g i n o f the s i l l s i s debatable. Some s i l l s are r e s i s t a n t g r a n i t i c rock which f o r p a r t of t h e i r l e n g t h r i s e above sea l e v e l as i s l a n d s or extend the s h o r e l i n e t o c r e a t e a narrows. S i l l s formed i n t e r m e d i a t e along the l e n g t h o f many i n l e t s are thought t o re p r e s e n t t e r m i n a l moraines d e p o s i t e d a t p o i n t s o f f u r t h e s t advance o f v a l l e y g l a c i e r s . I l l . R egional Geology The reconnaissance map of upper J e r v i s I n l e t by LeRoy (1908) shows Queen's Reach and P r i n c e s s Royal Reach t o be i n c i s e d i n a r o o f pendant o f p r e - Coast i n t r u s i v e r o c k s . LeRoy s t a t e d these rocks were P a l e o z o i c but James (1929) c o n s i d e r s them e a r l y Mesozoic. LeRoy r e c o g n i z e d two pre-Coast i n t r u s i v e rock u n i t s c o n s i s t i n g o f a secruence o f igneous rocks which he c o r r e l a t e d w i t h s i m i l a r rocks on Texada I s l a n d (the Texada Group) and a s e r i e s o f sedimentary rocks c o r r e l a t e d w i t h rocks at B r i t a n n i a Beach (the B r i t a n n i a Group). LeRoy found the B r i t a n n i a Group rocks ,to be by f a r the most abundant i n the upper J e r v i s I n l e t a r ea. The Texada Group outcrops near sea l e v e l i n a narrow band along the n o r t h - e a s t shore o f Queen's Reach between Malibu Rapids and the head o f J e r v i s I n l e t . James' (1929) work on the B r i t a n n i a Beach area shows a sequence o f v o l c a n i c s and sediments which he c o r r e l a t e d w i t h LeRoy's B r i t a n n i a Group. Bacon (1957) combined the Texada and B r i t a n n i a Groups o f LeRoy w i t h two ot h e r rock u n i t s and used the term J e r v i s Group t o i n c l u d e a l l rocks o f pre- b a t h o l i t h i c age. LEGEND JURASSIC OR LATER • Coast Rangs bathclith/' (mainly qucrtz diorita) n Quartz fold porphyry AGE UNKNOWN Cl Basalt, ondesite and J associated pyroclasticV • Argillite. conglomeratê * grsywacke, sandstono • Attitude of bedding, faults * inclined x vertical ^ fault with dip ' ... Boundaries geological ^ x „ . / watershed FIG. 2 MIDDLE AND UPPER JERVIS INLET SHOWING GEOLOGY AND DRAINAGE PATTERN GEOLOGY AFTER BACON (1957) AND LEROY (1908) : M M M vet*, i 17 T a b l e 2 Age Table o f Map U n i t s ( a f t e r Bacon,1957) Map U n i t D e s c r i p t i o n 8 mainly coarse g r a i n e d hornblende g r a n o d i o r i t e J u r a s s i c Coast 7 medium g r a i n e d b i o t i t e g r a n o d i o r i t e or l a t e r I n t r u - s i o n s 6 main b a t h o l i t h i c mass; quar t z d i o r i t e . g r a n o d i o r i t e 5 q u a r t z f e l d s p a r porphyry I n t r u s i v e Contact Age Un- known J e r v i s Group b a s a l t , a n d e s i t e and asso- c i a t e d p y . r o c l a s t i c s , minor limestone, d o l o m i t i c l i m e - stone, c h e r t , a r g i l l i t e mainly conglomerate., , grey- wacke, sandstone, a r g i l l i t e , greenstone metavolcanic rocks, meta- sedimentary rocks, metadiabase Gneiss D i s c r e p a n c i e s e x i s t where the p e r t i n e n t areas o f g e o l o g i c maps by Bacon (lower J e r v i s I n l e t ) and LeRoy (upper J e r v i s I n l e t ) o v e r l a p . However, a t e n t a t i v e map o f the geology of middle and upper J e r v i s I n l e t was compiled (Figure 2) u s i n g Bacon's nomenclatureo Judging from rock specimen d e s c r i t i o n s g i v e n by both authors, LeRoy 1s Texada and B r i t a n n i a Groups are approximately e q u i v a l e n t to Bacon's map u n i t s 4 and 3 r e s p e c t i v e l y . F i g u r e 4 1/6 square meter P e t t e r s s e n grab sampler ready t o be lowered b Edgerton, Germeshausen and G r i e r underwater camera assem- b l y . Not v i s i b l e i n p i c t u r e i s the compass and vane which i s suspended beneath the camera„ c R i g g i n g a Phleger c o r e r j u s t p r i o r t o l o w e r i n g . The t r i a n - gular-shaped p a r t w i t h arm i s a bottom c o n t a c t c r i p . 19 CHAPTER 3 METHODS OF STUDY I. F i e l d Methods 1) P o s i t i o n i n g The sample l o c a l i t i e s were chosen beforehand and p l o t t e d on a l a r g e - s c a l e c h a r t o f the area. P o s i t i o n - i n g was done by combined use of echo sounder and Decca r a d a r . Since the i n l e t i s narrow and v e r y s t e e p - s i d e d i n most i n s t a n c e s , radar was used t o good advantage. However, when more a c c u r a t e p o s i t i o n s were d e s i r e d so t h a t a s t a t i o n c o u l d be reoccupied, the p o s i t i o n was taken by s e x t a n t , Sampling s t a t i o n l o c a t i o n s are show i n F i g u r e 3 ( i n p o c k e t ) , 2) Sample C o l l e c t i o n Samples o f s u r f i c i a l sediments were c o l l e c t e d by use o f a P o t t e r s s e n grab sampler ( F i g u r e 4a) which sampled an area o f 5 . 9 square f e e t (1/6 square meter) . The ^4wkwardness o f t h i s sampler, due to i t s weight, was more than compensated f o r by i t s r e l i a - b i l i t y , e s p e c i a l l y when sampling the deep b a s i n s or p r e c i p i t o u s s i d e s o f the i n l e t . The u s u a l l y g e l a - t i n o u s b l o c k of sediment recovered was broken open and the l a b o r a t o r y sample was taken from the r e l a t i v e l y u n d i s t u r b e d i n t e r i o r . T h i s sample was p l a c e d i n a one- quart p l a s t i c c o n t a i n e r and s e a l e d w i t h p l a s t i c  21 e l e c t r i c a l tape. The remainder o f the sampler con- t e n t s was d i s c a r d e d . However, i f the sample c o n t a i n e d c oarse sand or g r e a t e r - s i z e d m a t e r i a l , the remainder o f the sample was s e i v e d w i t h a 10 mesh (2 mm) s e i v e and the +10 mesh m a t e r i a l was a l s o c o l l e c t e d . G r a v i t y cores were taken a l o n g the axes o f the b a s i n s u s i n g a 1%" (3.2 cm) diameter Phleger c o r e r ( F i g u r e 4c) and a 2 3/8" (6 cm) diameter g r a v i t y c o r e r . In both i n s t a n c e s the sample was r e t a i n e d w i t h i n a c l e a r p l a s t i c b a r r e l l i n e r which was removed from the c o r e r , capped and used f o r sample s t o r a g e . Experience showed i t was advantageous t o use both c o r e r s i n the f r e e - ' f a l l mode r a t h e r than w i t h a bottom c o n t a c t t r i p p i n g d e v i c e . The c o r e r was lowered u n t i l the meter block i n d i c a t e d the c u t t i n g edge was about 12 f e e t (4 m.) above the bottom. The winch was then stopped, taken out o f gear and allowed t o " f r e e - w h e e l " . Adequate p e n e t r a t i o n was achieved u s i n g a minimum number of weights. 3) Photography Underwater photographs were taken at s e l e c t e d s t a t i o n s u s i n g an Edgerton, Germeshausen and G r i e r photographic assembly (Figure 4b). T h i s c o n s i s t s o f an a u t o m a t i c a l l y timed 35 mm. camera and a 110 j o u l e s t r o b e f l a s h housed i n i d e n t i c a l but separate s t a i n l e s s 22 s t e e l p r e s s u r e r e s i s t a n t c y l i n d e r s . Both c y l i n d e r s are mounted on a frame - the camera i n the v e r t i c a l plane and the s t robe f l a s h angled so the i n t e r s e c - t i o n of the axes to the two u n i t s occurs at the f o c a l p o i n t o f the camera. Once s t a r t e d , the u n i t takes one p i c t u r e every 12 seconds u n t i l the b a t t e r y i s d r a i n e d , the f i l m i s consumed, or the u n i t i s r a i s e d t o the s u r f a c e and stopped by d i s c o n n e c t i o n o f the s y n c h r o n i z i n g or power l e a d . G e n e r a l l y , 100 f o o t r o l l s o f Kodak Plus-X f i l m w i t h an ASA r a t i n g o f 125 were used. With the camera focused a t 6 f e e t (1.8 meters), the optimum diaphragm opening was found t o be f8 - f l l . A compass was hung from the frame i n the camera f i e l d . The compass needle i s u s u a l l y v i s i b l e i n the photograph (sometimes s p e c i a l p r o c e s s i n g i s r e q u i r e d ) . The compass assembly i n c l u d e s a 10 i n c h (25 cm) vane, which, by propor- t i o n i n g , can be used t o determine s c a l e as w e l l as t o i n d i c a t e c u r r e n t d i r e c t i o n . At the time the photographic s t a t i o n s i n J e r v i s I n l e t were occupied, the assembly was p o s i t i o n e d a t the c o r r e c t d i s t a n c e o f f the bottom by t r i a l and e r r o r . The assembly was f o l l o w e d by echo-sounder u n t i l near the bottom. 23 When 3 t o 6 fathoms o f f bottom, the r a t e o f l o w e r i n g was decreased u n t i l the bottom was touched by the l e g s o f the frame. T h i s touchdown c o u l d be d e t e c t e d a t the winch. The assembly was then r a i s e d t o the d e s i r e d h e i g h t o f f the bottom. T h i s procedure was repeated every 5 t o 10 minutes w h i l e on s t a t i o n . Useable p i c t u r e s were ob t a i n e d but the success r a t i o was o n l y about one frame i n twelve and sometimes one i n twenty depending on the depth o f o p e r a t i o n . Subsequently, a b o t t o m - f i n d i n g p i n g e r has been i n c l u d e d i n the assembly. An o m n i d i r e c t i o n a l t r a n s - ducer pings a t a s e t r a t e thus a l l o w i n g the d i s t a n c e from the assembly to the bottom t o be measured from the d i f f e r e n c e i n a r r i v a l times between the d i r e c t p u l s e and the r e f l e c t i o n o f the p u l s e from the bottom. The use of t h i s p i n g e r on other p r o j e c t s r e s u l t e d i n an i n c r e a s e o f the success r a t i o t o one frame i n f i v e or sor.etimes l o o s b^Wef. The f i l m s were processed commercially a f t e r the c r u i s e r e t u r n e d . Lack o f space, time and necessary equipment aboard s h i p p r e c l u d e d on-the-spot p r o c e s s - i n g , which however, would have been advantageous. 24 4) Echo Sounding and Continuous Seismic P r o f i l i n g The foathymetric map o f J e r v i s I n l e t ( F i g u r e 6 - i n pocket) was drawn from the Canadian Hydro- g r a p h i c S e r v i c e F i e l d Sheet No. 2228-L e n t i t l e d " J e r v i s I n l e t — Northern P o r t i o n " . However, a more d e t a i l e d survey was made o f the manganese c o n c r e t i o n l o c a l i t y . F i v e l i n e s were run t r a n s v e r s e t o the axes o f the i n l e t over P a t r i c k S i l l . These were t i e d i n by four l i n e s run c o n s e c u t i v e l y on a r e c t a n g u l a r p a t t e r n . A 38 KHz Kelvin-Hughes sounder gave good re c o r d s , even though the subsurface topography was steep. P o s i t i o n s were p l o t t e d every two minutes by Decca ra d a r . T h i s data was c o r r e c t e d and aombined w i t h data from the F i e l d Sheet i n order t o compile a l a r g e - s c a l e bathymetric map of P a t r i c k S i l l ( F i g u r e 37 - i n p o c k e t ) . During I.O.U.B.C. C r u i s e 66/1, a continuous s e i s m i c p r o f i l e was made from the head t o the mouth of J e r v i s I n l e t ( T i f f i n and Murray, 1966). The 5000 j o u l e s e i s m i c p r o f i l i n g equipment c o n s i s t e d o f Edgerton, Germeshausen, and G r i e r power supply, c a p a c i t o r banks, and t r i g g e r , coupled t o a "spark- a r r a y " t r a n s d u c e r . Echos were p i c k e d up by hydro- phone, a m p l i f i e d , f i l t e r e d , and then rec o r d e d by an Alden wet-paper P r e c i s i o n Graphic Recorder. 25 I I . L a b o r a t o r y Methods 1) G r a i n S i z e D i s t r i b u t i o n i n Sediments The procedure f o r p r o c e s s i n g a sample i s i l l u s - t r a t e d i n F i g u r e 5. Each sample was kept f r o z e n u n t i l a nalyzed. To begin, the sample was f i r s t thawed and then homogenized by s t i r r i n g . Three sub- samples were taken by means o f a 5/8 i n c h (16 mm) i n s i d e diameter g l a s s tube w i t h a t a p e r e d c u t t i n g edge. The sub-sample was e x t r a c t e d by r o t a t i n g the tube and a p p l y i n g a s l i g h t vacuum by mouth t o the f r e e end. As the tube was pushed i n t o the sediment, the l e v e l o f the sediment w i t h i n the tube was kept the same as t h a t surrounding. In t h i s way, any b i a s i n g o f g r a i n s i z e parameters e t c . by sub-sampling techniques was h o p e f u l l y minimized. The sub-samples f o r c l a y m i n e r a l a n a l y s i s and t o t a l carbon content were a i r - d r i e d . Carbon analyses were made u s i n g a Leco i n d u c t i o n furnace and CO2 a b s o r p t i o n system. G r a i n s i z e analyses were made by dry s i e v i n g f o r the y 63/u m a t e r i a l and by hydrometer f o r the <(63^u m a t e r i a l . Before s i e v i n g , the )> 63/u m a t e r i a l was g i v e n s u c c e s s i v e treatments w i t h hydrogen peroxide i n order t o d i s s o l v e o r g a n i c components. T h i s s t e p was i n c l u d e d as the c o n c e n t r a t i o n of o r g a n i c s was s u f f i c i e n t t o prevent d i s a g g r e g a t i o n 26 CLAY MINERAL SAMPLE ANALYSIS ' - a — ' ( X-RAY DIFFRACTION ) WASH WITH" DISTILLED H90 MOISTURE CONTENT TOTAL CARBON CONTENT (LECO) CENTRIFUGE SUPERNATANT SALT — EVAPORATE LIQUID CONTENT .SEDIMENT - WET SIEVE WITH DISPERSANT + 6 2 ^ FRACTION 62/* FRACTION. WASH WITH H20 AND DRY DISSOLVE ORGANICS (HgOg) DRY SIEVE (\/Z 0 INTERVAL) + 62,*. FRACTIONS STORE -f 125^ 1 - 62^ FRACTION FRACTIONS -125 4-62/.'- FRACTIONS r BROMOFORM, SEPARATION LIGHTS HEAVIES t t Is*, rxr> « a «a» e=» «=» c=» .SPLIT FOR GRAIN STIR AND MAKE UP TO IOOO ml. ! HYDROMETER ANALYSIS PIPETTE FOR Tt) MOUNTS 27 e s p e c i a l l y i f the sediment was d r i e d . Grains w i t h a diameter o f <̂  6 3 d e r i v e d from s e i v i n g the coarse f r a c t i o n were added t o the sedimentation c y l i n d e r s b e f o r e the hydrometer analyses were made. Hydrometer analyses were conducted a c c o r d i n g t o ASTM s p e c i f i c a t i o n (ASTM D422-61T) u s i n g a 152H hydrometer. The i n i t i a l weight o f the sub-sample f o r g r a i n s i z e a n a l y s i s was estimated so the<^63/u m a t e r i a l would weigh from 10 t o 15 grams. P r e l i m i n - ary a n a l y s i s i n d i c a t e d t h i s weight of m a t e r i a l i n suspension gave optimum r e s u l t s . A l l hydrometer analyses were done at 84°F (30°C) because room temperature was not l i k e l y t o exceed t h i s tempera- t u r e . The co n s t a n t temperature bath used maintained the s e t temperature as long as t h i s was above ambient. However, the bath had no d i r e c t means o f c o o l i n g i f ambient exceeded set temperature. I n i t i a l l y , the t i n e s a t which hydrometer r e a d - ings should be made t o d e r i v e a weight d i s t r i b u t i o n i n even 0 v a l u e s ( i . e . 4 . 5 0 , 5 0 , 60, e t c . where 0 = -log2 g r a i n diameter i n mm.) were taken from a c h a r t c a l c u l a t e d f o r the s e t t l i n g v e l o c i t i e s o f q u a r t z spheres. However, these times d i d not g i v e the weight d i s t r i b u t i o n i n even 0 v a l u e s f o r the material- b e i n g 28 analysed. Through a series of successive approxi- mations, appropriate reading times were calculated. The t o t a l weight of sediment i n the -63/u fr a c t i o n (tj2f weight) was d i f f i c u l t to determine by hydrometer. Thus when a hydrometer analysis was complete, the sediment was s t i r r e d back into suspen- sion, and the tj# weight was determined by immediately pipet t i n g o f f 50 ml of suspension. 2) Mineralogy of Sediments Mineral analyses were c a r r i e d out on select samples taken from the axes of the basins. The 63/u to 88/u and the 88/u to 125/u seive samples were combined and then a heavy mineral separation was made using bromoform. Thin sections were made of both the l i g h t and heavy fractions and the mineralogy was determined petrographically by point-counting. The clay mineral analyses were conducted on separate sub-samples of the main sample. The size fractions were separated according to the procedure described by K i t t r i c k and Hope (1963). X-ray d i f f r a c t i o n analyses were c a r r i e d out on the 20 - 5/u, 5 - 2/u, and 2yu f r a c t i o n s . The \2^u fr a c t i o n was given a series of treatments to a i d i n 29 i d e n t i f i c a t i o n o f the c l a y m i n e r a l s p r e s e n t . These were K s a t u r a t i o n , K s a t u r a t i o n h e a t i n g t o 300°C, K s a t u r a t i o n h e a t i n g t o 500°C, Mg s a t u r a t i o n and Mg and g l y c e r o l s a t u r a t i o n , The i r o n e x t r a c t e d i n p r e p a r a t i o n of the c l a y s f o r X-ray a n a l y s i s was determined by atomic a b s o r p t i o n spectrophotometer. 3) G r a v i t y Core Analyses The l a r g e diameter g r a v i t y cores were s p l i t by u s i n g a c i r c u l a r saw t o c u t the core b a r r e l and a p i e c e o f t h i n piano wire t o c u t the sediment. S t r u c t u r e s i n the sediments were r e v e a l e d by running a stream of water down the c u t f a c e . No ana l y s e s were c a r r i e d out on the sediments due to time l i m i t a t i o n s . The cores were s e a l e d i n con- t a i n e r s f o r f u t u r e r e f e r e n c e . 4) Composition, S t r u c t u r e and Abundance o f Manganese-Iron C o n c r e t i o n s The elemental composition o f the manganese c o n c r e t i o n s was determined by Dr. E. V. G r i l l o f the I n s t i t u t e o f Oceanography a t the U n i v e r s i t y o f B r i t i s h Columbia ( G r i l l , Murray and Macdonald 1968). The S p e c i a l P r o j e c t s D i v i s i o n o f Bear Creek Mining Company L t d . and the B.C. Department of Mines c a r r i e d out independent a n a l y s e s . The mineralogy o f the c o n c r e t i o n s was determined by X-ray d i f f r a c t i o n . 30 P o l i s h e d s e c t i o n s o f the c o n c r e t i o n s were made f o r r e f l e c t e d l i g h t s t u d i e s and photographic purposes. To make the s e c t i o n s , the c o n c r e t i o n s were f i r s t impregnated due t o t h e i r v e r y f r i a b l e n a t u r e . Impregnation was c a r r i e d out i n a vacuum d e s s i c a t o r u s i n g C a s t o l i t e r e s i n . The p r o p o r t i o n s of r e s i n t o t h i n n e r t o hardener used were i n the r a t i o o f 24 mis. t o 8 mis. to 3 drops. A c u r i n g time o f 24 hours i n an oven a t 80°C was used. The e n t i r e c o n c r e t i o n was impregnated and then c u t . A second impregnation was necessary b e f o r e the c u t s u r f a c e c o u l d be p o l i s h e d s a t i s f a c t o r i l y . The f i n a l p o l i s h i n g was done on a diamond l a p . The estimate o f the weight o f d r i e d manganese c o n c r e t i o n a r y m a t e r i a l per u n i t area was made from a t y p i c a l 1/6 meter 2 (1.8 f e e t 2 ) P e t t e r s s e n grab sample. The c o n c r e t i o n s recovered were d r i e d and oxide m a t e r i a l s were broken away from the n u c l e a t - i n g rock fragments and weighed. 31 CHAPTER 4 OCEANOGRAPHY I. Bathymetry The study area encompasses two b a s i n s separa- t e d by a s i l l . The upper or more n o r t h e r l y b a s i n c o i n c i d e s w i t h Queen's Reach, w h i l e the lower c o i n - c i d e s w i t h the upper t w o - t h i r d s o f P r i n c e s s Royal Reach. The bathymetric map i s presented i n F i g u r e 6 ( i n p o c k e t ) . The s i l l depth o f the upper b a s i n i s 160 fathoms (290 meters), w h i l e t h a t o f the lower i s 220 fathoms (400 meters). The maximum depths are 190 and 290 fathoms (348 and 530 meters) r e s - p e c t i v e l y . The sl o p e along the b a s i n a x i s a t the head o f the i n l e t measures 1°50', but r a p i d l y i n c r e a s e s t o 10°36'. Beyond S t a t i o n J-102, the slo p e s l o w l y decreases t o an average o f 0°14' f o r the remainder o f the l e n g t h o f the upper b a s i n . The s l o p e o f the bottom o f the second b a s i n i s approximately 0 ° 0 2 1 . The s o u t h - f a c i n g f l a n k o f P a t r i c k S i l l d i p s at 18°30' on the a x i a l l i n e but the angle i n c r e a s e s towards the i n l e t s i d e s . Transverse s e c t i o n s ( F i g u r e 7) i l l u s t r a t e the m o d i f i e d catenary or U-shaped c r o s s - s e c t i o n which i s t y p i c a l o f g l a c i a l l y - s c o u r e d v a l l e y s . 32 In the upper b a s i n , the 160 fathom (293 meter) contour marks the approximate break i n slope between the sides and bottom of the i n l e t . In the lower b a s i n , the break i n slope occurs at 280 fathoms (513 meters). The slope of the i n l e t s ides ranges from 10° to 47° and probably averages about 35°. Echo and wire soundings at S t a t i o n J-160 i n d i c a t e a very steep slope. The echo- sounder recorded a depth of 200 fathoms (366 meters), w h i l e a wire sounding gave a depth of 292 fathoms (534 meters). P i c k a r d (1961) noted from transverse s e c t i o n s t h a t a f l a t bottom was c h a r a c t e r i s t i c of the upper b a s i n and was most pronounced j u s t i n s i d e the s i l l a t the deepest p o r t i o n of the b a s i n . From t h i s and other data ( i . e . o p t i c a l t u r b i d i t y ) , P i c k a r d p o s t u l a t e d the e x i s t e n c e of t u r b i d i t y c u r r e n t s w i t h i n the upper b a s i n . A l s o n o t i c e a b l e on the s e c t i o n s i s the transverse asymmetry of the i n l e t at sea l e v e l and below. The bathymetric map of Upper J e r v i s I n l e t shows s e v e r a l banks w i t h i n the upper b a s i n , w h i l e none appear w i t h i n the lower b a s i n . These features are found along the margins of the i n l e t . A l s o n o t i c e a b l e i s the biconcave or v e n t u r i shape of 55 Vertical Scale » Horizontal Scolo Nautical Miloo FIG. 7 TRANSVERSE SECTIONS P a t r i c k S i l l . Pi s e c t i o n t r a n s v e r s e t o the b a s i n a x i s through P a t r i c k S i l l r e v e a l s a d i s t i n c t medial d e p r e s s i o n or "V" notch. The o r i g i n o f these f e a t u r e s w i l l be d i s c u s s e d l a t e r . I I . Temperature and S a l i n i t y ( a f t e r L a z i e r , 1963) The average v e r t i c a l p r o f i l e s o f temperature and s a l i n i t y f o r J e r v i s I n l e t i n March 1962 are g i v e n i n F i g u r e 8. These r e p r e s e n t more or l e s s s t a b l e c o n d i t i o n s d u r i n g the year L a z i e r s t u d i e d the i n l e t c i r c u l a t i o n (March 1962 - March 1963). Temperature °C Salinity %o a co o E 100- Figure 8 Average Vertical Profiles of Temperature and Salinity for Jervis inlet during M a r c h i 9 6 2 After Lazier , IS63 35 The average salinity-depth p r o f i l e indicates that over most of the i n l e t there i s a lack of a homogeneous surface layer of low s a l i n i t y and thus there i s no d i s t i n c t h a l o c l i n e . The s a l i n i t y increases from the surface to depth with a decreas- ing rate. Surface water s a l i n i t y reaches 50% of the deep-water s a l i n i t y at a depth of about one fathom, and 90% of the deep-water s a l i n i t y within a depth of between 4 to 11 fathoms„(Pickard 1961). The average temperature-depth p r o f i l e resembles the salinity-depth p r o f i l e . However, as the mean da i l y temperature increases with the advent of summer, the surface waters warm considerably r e s u l t i n g i n the formation of a temperature minimum at about 15 fathoms. This minimum remains i n evidence u n t i l October. At this time the decreasing surface temperature results i n a temperature maximum at about the 15 fathom depth. I I I . Oxygen Content and C i r c u l a t i o n (after Lazier 1963) Je r v i s Inlet i s classed as a deep-silled i n l e t i n that the s i l l at the mouth i s of s u f f i c i e n t depth so that t i d a l waters may enter and leave without unduly modifying the v e r t i c a l s t r a t i f i c a - t i o n of the resident i n l e t waters. Flows may occur 36 i n both d i r e c t i o n s s i m u l t a n e o u s l y . Since the s u r f a c e r u n o f f i n t o J e r v i s I n l e t i s s m a l l , the e s t u a r i n e c i r c u l a t i o n i s g e n e r a l l y weak. Changes i n m e t c o r l o g i c a l and oceanographical con- d i t i o n s i n the area w i l l produce flows which w i l l dominate the e s t u a r i n e c i r c u l a t i o n . Oxygen p r o f i l e s d i s p l a y most d i s t i n c t l y the c i r c u l a t i o n w i t h i n the i n l e t . ( F i g . 9 ) L a z i e r des- c r i b e d a mid-depth o s c i l l a t o r y flow o f unknown p e r i o d which o c c u r r e d d u r i n g the w i n t e r o f 1963-63. A p o s s i b l e mechanism f o r t h i s flow i s d e s c r i b e d by L a z i e r as f o l l o w s : " I t was proposed t h a t s t r o n g southwesterly winds i n the autumn, p a r t i c u l a r l y those a s s o c i a t e d w i t h Typhoon F r i e d a , caused the water l e v e l w i t h i n J e r v i s I n l e t t o r i s e . To compensate f o r the i n c r e a s e i n water volume, a mid-depth outflow was c r e a t e d . T h i s outflow produced a h o r i z o n t a l p r e s s u r e g r a d i e n t t h a t tended t o r e v e r s e the d i r e c t i o n o f the flow. When the flow reversed, the water l e v e l i n the i n l e t a g a i n became g r e a t e r , and the s u r f a c e outflow i n c r e a s e d . A n e g a t i v e c o r r e l a t i o n between the d i r e c t i o n of the mid- depth flow and the depth of the s u r f a c e l a y e r was noted. The low oxygen content i n the water at mid- depths near the head o f J e r v i s I n l e t was a t t r i b u - t e d t o weak e s t u a r i n e c i r c u l a t i o n ;which r e s u l t s i n slow removal o f water near the head." FIGURE 9 WATER CIRCULATION AS AFTER LAZIER, 1963 INDICATED BY LONGITUDINAL OXYGEN PROFILES I V . T i d e s The B r i t i s h C o l u m b i a c o a s t i s s u b j e c t t o s e m i - d i u r n a l t i d e s w h i c h h ave marked i r r e g u l a r i t i e s b e t w e e n t h e h e i g h t s o f s u c c e s s i v e low w a t e r s . The t i m e o f e i t h e r h i g h o r low w a t e r a t t h e h e a d s o f t h e i n l e t s i s n o t more t h a n t e n m i n u t e s l a t e r t h a n a t t h e mouth. The r a n g e a t t h e h e a d i s f r o m 1 t o 1 p e r c e n t g r e a t e r t h a n a t t h e mouth ( P i c k a r d , 1 9 6 1 ) . C u r r e n t d i r e c t i o n s were c a l c u l a t e d f o r t h e man g a n e s e l o c a l i t y ( S t a t i o n J-19-67) by u s e o f t h e compass w h i c h hangs i n t h e f i e l d o f v i e w o f t h e u n d e r w a t e r c a m e r a . The d i r e c t i o n s i n d i c a t e d c o i n - c i d e w i t h t h e d i r e c t i o n o f t h e s u r f a c e t i d a l f l o w i . e . n o r t h w e s t on a f l o o d t i d e and s o u t h w e s t on a n ebb t i d e . Measurements were made when t h e compass was 1 t o 2 f e e t f r o m t h e b o t t o m . V. O p t i c a l T u r b i d i t y ( a f t e r P i c k a r d and G i o v a n d o , 1960) F i g u r e 10 i l l u s t r a t e s measurements o f o p t i c a l t u r b i d i t y made i n J e r v i s I n l e t on two o c c a s i o n s - F e b r u a r y 1958 a n d J u n e 1958. A l i g h t - s c a t t e r i n g method o f measurement was u s e d a n d v a l u e s o f o p t i c a l t u r b i d i t y r e p r e s e n t f r a c t i o n a l r e d u c t i o n i n l i g h t i n t e n s i t y p e r m e t e r l e n g t h due t o s c a t t e r i n g . D a t a i n d i c a t e s t h a t t h e m a j o r i t y o f s u s p e n d e d m a t e r i a l was m i n e r o g e n i c , 59 JUNE 1958 FIG. 10 OPTICAL TURBIDITY ALONG JERVIS INLET 4 0 r e l a t i v e l y t r a n s p a r e n t , and o p t i c a l l y a n i s o t r o p i c . A l s o i n d i c a t e d was the presence o f white opaque p a r t i c l e s or t r a n s p a r e n t m a t e r i a l w i t h m u l t i p l e i n t e r n a l r e f l e c t i n g s u r f a c e s . In the s u r f a c e water samples c o l l e c t e d i n June, the diameters o f the suspended p a r t i c l e s ranged from 0 . 7 5 t o 4 9 / u w i t h a geometric mean o f 1 6 . 7 ± 1 . 5 / u . Inorganic m a t e r i a l s accounted f o r 9 9 per cent o f the t o t a l . Samples c o l l e c t e d i n February c o n t a i n e d p a r t i c l e s w i t h diameters ranging from 0 . 5 t o 1 5 / u having a geometric mean o f 7 . 3 + 1 . 5 / u . In these, i n o r g a n i c m a t e r i a l s accounted f o r 9 0 per cent o f the t o t a l . P i c k a r d suggests, as a b o l d estimate, a sedimen- t a t i o n r a t e o f 3 5 cm. per 1 0 0 0 y e a r s . Current measurements made i n Knight I n l e t ( P i c k a r d and Rodgers, 1 9 5 9 ) show t h a t a t a d i s t a n c e o f 2 7 fathoms above the bottom i n 1 9 0 fathoms o f water, t h e r e e x i s t s a c u r r e n t o f t i d a l p e r i o d o f a few c e n t i m e t e r s per second. Thus the i n c r e a s e i n t u r b i d i t y i n the bottom waters o f Queen's Reach, as i l l u s t r a t e d i n F i g u r e 1 0 , may be due t o a s i m i l a r c u r r e n t r e a c h i n g the bottom sediments. As an a l t e r - n a t i v e , P i c k a r d p o s t u l a t e s the e x i s t e n c e o f t u r b i d i t y c u r r e n t s . 41 CHAPTER 5 BASIN STRUCTURE AND SEDIMENT THICKNESS Figure 11 i s a tracing from a continuous s e i s - mic p r o f i l e made by Dr. J . W . Murray and Dr. D. L . T i f f i n of the Insti t u t e of Oceanography, University of B r i t i s h Columbia. The course along -which the p r o f i l e was taken appears at the lower l e f t hand corner of the figure, and also on Figure 3 (in pocket) with positions of sample stations. The "Spark-array" transducer produces an acoustic pulse by means of an instantaneous arc discharge underwater. The arc creates a plasma bubble, which rapidly expands and then collapses. The outgoing wave form consists of several peaks, and therefore, on the seismic record,a r e f l e c t i n g layer w i l l appear as a c l o s e l y spaced series of l i n e s rather than one. Return or r e f l e c t e d energy i s f i l t e r e d and only that with a frequency i n the 40 to 2 0 0 Hzrange i s recorded. Use of low frequen- cies r e s u l t s i n good penetration but poor d e f i n i t i o n . T i f f i n (oral comm,1969) estimates that a horizontal layer must have a minimum thickness of about 5 fathoms (9 meters) before i t can be detected. On a slope t h i s minimum thickness increases. 42 The slow f i r i n g r a t e o f the t r a n s d u c e r (one or more seconds per p u l s e depending on depth and energy/pulse) r e s u l t s i n a r e c o r d on which the v e r t i c a l s c a l e i s g r e a t l y exaggerated and apparent angles are much st e e p e r . The v e r t i c a l s c a l e on the r e c o r d e r i s c a l i b r a t e d w i t h r e s p e c t t o the speed o f sound i n sea water (about 4800 f e e t / s e c o n d ) . However, the speed o f sound i n Recent and P l e i s t o - cene sediments v a r i e s from about 4800 t o 7800 f e e t / second. (Dobrin, 1960). T h e r e f o r e sediment t h i c k - ness taken from a seismi.c r e c o r d must be m u l t i p l i e d by the r a t i o o f the speed of sound i n the m a t e r i a l / 4800 f ° r c o r r e c t i o n . The r e c o r d presented i n F i g u r e 11 may be c o n f u s - i n g because many underwater peaks are e v i d e n t . How- ever, s i n c e the course f o l l o w e d was a z i g - z a g p a t t e r n , many o f the apparent peaks r e s u l t from approach t o and t u r n i n g away from the s h o r e l i n e . A l s o , as the s h i p ' s speed was not constant, the h o r i z o n t a l s c a l e i s v a r i a b l e . N o t i c e a b l e i n F i g u r e 11 i s the r e l a t i v e l y uniform sediment t h i c k n e s s i n the b a s i n s . With the ex c e p t i o n s o f the very t h i c k accumulation o f f Malibu Rapids, sediment t h i c k n e s s i n the upper  44 b a s i n averages about 480 f e e t or 146 meters (assum- in g an average speed o f sound t o be 7000 f e e t / s e c o n d ) . The t h i c k n e s s e s range from 480 f e e t (146 meters) f o r s e c t i o n B-C t o 67 2 f e e t (205 meters) f o r s e c t i o n F-G and 336 f e e t (102 meters) f o r s e c t i o n G-H. The i n c r e a s e i n t h i c k n e s s i n s e c t i o n F-G i s probably due t o a d d i t i o n o f m a t e r i a l from the d e l t a at M a l i b U o In the lower b a s i n the average sediment t h i c k n e s s i s 720 f e e t (220 meters). R e f l e c t i n g h o r i z o n s w i t h i n the sediments are thought t o re p r e s e n t bedding p l a n e s . On the sl o p e at the head o f the i n l e t the more r e c e n t beds d i p g e n t l y t o the southeast (i.e.down the i n l e t ) . These beds appear t o o v e r l i e f l a t - l y i n g b a s a l sediments, apparent i n s e c t i o n B - C o f F i g u r e 11. Unfortun- a t e l y , o n l y the base of the sl o p e was covered by the s e i s m i c l i n e and t h e r e f o r e the extent o f the unconformity i s not known. I f the unconformity i s t r a c e a b l e t o the i n l e t head, perhaps i t r e p r e s e n t s the o v e r l a p p i n g o f re c e n t sediments d e p o s i t e d by slumping on sediments d e p o s i t e d d u r i n g s h e l f i c e c o n d i t i o n s . D etermination o f sediment t h i c k n e s s on s l o p e s such as the i n l e t w a l l s and the s i l l cannot be made 45 because o f r e c o r d d i s t o r t i o n i n h e r e n t i n the use o f a low frequency and wide beam angle t r a n s d u c e r . However, the a c t i o n o f the grab sampler as d e t e c t e d by hand on the winch c a b l e and the damage done t o the grab w h i l e sampling the i n l e t w a l l s and V-notch of the s i l l , i n d i c a t e t h a t the sediment cover i s o f t e n t h i n and sometimes l a c k i n g . A l s o , one o f the underwater photographs ( F i g u r e 29a) taken i n the c o n c r e t i o n l o c a l i t y shows what i s l i k e l y bedrock but p o s s i b l y a l a r g e g l a c i a l e r r a t i c . Iron c r u s t s ( F i g u r e 44) and sponges r e c o v e r e d from t h i s l o c a l i t y appear t o have been broken o f f rock f a c e s . Although l i t t l e or n o t h i n g can be determined about a c t u a l sediment t h i c k n e s s e s which have accumulated on slo p e s , or i n the V-notch, some doubt i s c a s t on the t e r m i n a l moraine o r i g i n o f s i l l s . P a t r i c k S i l l and other s i m i l a r s i l l s have u s u a l l y been regarded as t e r m i n a l moraines o r i g i n a - t i n g from i c e advance d u r i n g the Sumas Stade. The concavo-convex shape o f some s i l l s (ecg.the i n n e r s i l l o f Howe Sound) tend t o support t h i s e x p l a n a t i o n . However, l i t t l e i s known about the extent o f Sumas Stade g l a c i a t i o n except f o r the advance i n the Sumas area o f the F r a s e r V a l l e y . Evidence suggests P a t r i c k S i l l i s not a t e r m i n a l moraine but a bedrock f e a t u r e 46 c o v e r e d , f o r the most part, by a sediment veneer o f v a r y i n g t h i c k n e s s . S e v e r a l exposed s i l l s are bed- rock f e a t u r e s and t h e i r p o s i t i o n w i t h r e s p e c t t o former i c e flow channels o f f e r s a p o s s i b l e explana- t i o n f o r thej.r formation. Major s i l l s are g e n e r a l l y l o c a t e d a t p o i n t s where v a l l e y s which c o n f i n e d the i c e suddenly widen or, i n the v a l l e y s of s m a l l e r g l a c i e r s where these met trunk g l a c i e r s a t or near r i g h t a n g l e s . The s i l l c r e a t i n g Malibu Rapids i s an example o f the l a t t e r . At t h i s p o i n t a s m a l l e r g l a c i e r would have c o a l e s c e d w i t h a much l a r g e r i c e mass moving a t r i g h t a n g l e s . At the p o i n t where co a l e s c e n c e o f the i c e masses occurred, the downward e r o s i v e capab- i l i t y o f the s m a l l e r would l i k e l y be decreased r e s u l t i n g i n a s i l l . The s i l l a t M alibu i s a bedrock f e a t u r e and biconcave i n p l a n . view. P o s s i b l y g l a c i a l a c t i o n only s c u l p t u r e d the s i l l and the b a s i c c o n t r o l i s s t r u c t u r a l . Intense s h e a r i n g a t the p o i n t o f c o a l e s c e n c e o f the i c e masses would a l s o mean t h a t as the i c e masses began to waste, these areas would melt the most r a p i d l y due t o the g r e a t e r s u r f a c e areas exposed by f r a c t u r e s u r f a c e s . In t h i s way,depending 47 on sea l e v e l , the biconcave p l a n and e s p e c i a l l y the V-notch o f s i l l s may be accentuated as these areas •would form s i n k s f o r the i n i t i a l l y d e r i v e d g l a c i a l d e b r i s . As wasting o f the i c e masses progressed, more and more o f the r e l e a s e d sediments would be d e p o s i t e d over the b a s i n as a whole. The bathyraetric map of the study area (Figure 6) shows the presence of bank or r i d g e - l i k e f e a t u r e s along the s i d e s o f the upper b a s i n . These f e a t u r e s are not present i n the lower b a s i n . Even though s e i s m i c r e c o r d s are poor because of the s l o p e i n v o l v e d , they i n d i c a t e t h a t the banks, l i k e the s i l l , a re bedrock f e a t u r e s - p o s s i b l y g l a c i a l l y s c u l p - t u r e d g r a n i t i c plugs w i t h i n the r o o f pendant o f s h a l e . S e v e r a l such plugs are known t o e x i s t a l o n g the shore of the upper b a s i n as the c o n t a c t s have been e x p l o r e d f o r economic m i n e r a l s . CHAPTER 6 SEDIMENTS A sample recovered w i t h a P e t t e r s s e n grab sampler r e p r e s e n t s a t l e a s t the top 20 t o 30 c e n t i - meters o f sediment, assuming the m a t e r i a l has the c o n s i s t e n c y o f a t y p i c a l marine s i l t y c l a y . I f P i c k a r d ' s estimate o f 35 cm/1000 years f o r the sedimentation r a t e i n J e r v i s I n l e t i s assumed c o r r e c t , a grab sample c o u l d c o n c e i v a b l y r e p r e s e n t a s e c t i o n w i t h an age span o f about 550 to 850 year While t h i s i s only an example, i t does i l l u s t r a t e t h a t parameters d e r i v e d from l a b o r a t o r y a n a l y s i s o f sediment c o l l e c t e d by grab sampler r e p r e s e n t o n l y a crude average taken over an i n d e t e r m i n a b l e number o f y e a r s . I n t e r p r e t a t i o n based on these parameters should be made w i t h t h i s i n mind. The s u r f i c i a i sediments were c l a s s i f i e d t e x t u r - a l l y a c c o r d i n g t o a scheme proposed by Shepard (1954). B a s i c a l l y , the sediments c o n s i s t of equal p a r t s of s i l t and c l a y - s i z e d p a r t i c l e s ( F i g u r e 12) w i t h the amount o f sand and g r a v e l v a r y i n g from 0.5 t o 85 per c e n t . T h i s c h a r a c t e r i s t i c i s a l s o n o t i c e a b l e i n data presented by Cockbain (Cockbain 1963) f o r Vancouver I s l a n d i n l e t s . Cockbain's data A / A A ' A A / A A A A \A.- \'\.'}j,\/\>\'"\'\ CLASSIFICATION OF JERVIS SEDIMENTS ACCORDING TO SIZE DISTRIBUTE Depth lass than 100 fathoms Dspth greater than 100 fathoms GRAVi e n d S A N D A V O \ A ? \ / \ A / V \ ^ A~A Vi\~A/•./\'\X-V"A••• v\AA£r"/VVvVV\T)vUVYlViAAAA7y\A/Wv\ /\/w\~\A~A ATT Q/</?'A'"A. A^A A A AA A A AAMa? A AA/\ A , \ AA A/w\/ V V V A A <\ A A / . A A A . V/(T> \ A V Y S I \/y\/\AA/\A/\/v\A/\/\Ayy>/\/v\A/-.AA/\/\ A > t \ \ A . y\ -v./* ~/^'y\'AVy\/\/V\/\/\/\/yi>/\^/\A/\MO'\Ao/VV A ' T O W i '»/ A f o V * A A y \ ; \ A A ? V » ' V V \ ^ A A A ^ v ^ ^ ' A A J V ^ v\//V\n/\/V° J A / V V A A A A A A A A A A V ^ "A V-A7\7X->yV/rA/yV V \ A ? A A A7Y _ ; - A A A / w N / \ A / V \ A A A A A A 7 \ A / W CLA' 50 f o r mainland i n l e t s , p l o t t e d i n the same manner, i n d i c a t e s a s l i g h t skewness towards c l a y - s i z e d p a r t i c l e s , w i t h the average abundance o f sand and g r a v e l l e s s than f o r J e r v i s I n l e t . T h i s d i f f e r e n c e may be a r e s u l t of d i f f e r e n c e s i n sampling p a t t e r n and/or the below average sedimentation r a t e i n J e r v i s I n l e t . F i g u r e 13, showing sediment g r a i n s i z e d i s t r i - b u t i o n along the a x i s o f upper J e r v i s I n l e t i s presented as a r e f e r e n c e t o the d i s c u s s i o n o f t o t a l carbon content, f r e e i r o n content and mineralogy o f the sediments. In each o f the f i g u r e s s i m i l a r t o F i g u r e 13 the data b e i n g presented i s superimposed on the bottom p r o f i l e taken along the i n l e t a x i s . I. Colour The c o l o u r of the wet sediments i s c h a r a c t e r i s - t i c o f the c o a s t a l marine p r o v i n c e and v a r i e s from a g r e y i s h o l i v e (10Y4/2) t o an o l i v e grey (5Y3/2). The sediments o f the upper b a s i n tend t o be more l i g h t l y c o l o u r e d ( i . e . g r e y i s h o l i v e ) w h i l e those i n the lower tend towards the darker o l i v e grey c o l o u r . Samples c o l l e c t e d along the axes o f the lower b a s i n from S t a t i o n J-146 southward c o n t a i n e d v a r v e - l i k e l a m i n a t i o n s o f o l i v e grey a l t e r n a t i n g  52 w i t h b l a c k m a t e r i a l . These were the o n l y samples w i t h i n the lower b a s i n t o c o n t a i n d i s t i n c t concen- t r a t i o n s o f H2S. Samples from the upper b a s i n which c o n t a i n e d n o t i c e a b l e c o n c e n t r a t i o n s o f H2S were c o l l e c t e d nearshore i n r e l a t i v e l y shallow waters ( S t a t i o n J-101, J-102, and J-128). Cores taken by Dr. E. V. G r i l l i n d i c a t e the presence o f a t h i n (approx. 0.5.to 1.5 cm) and very f l u i d , dark yellow-brown to red-brown o x i d i z e d l a y e r which forms at the sediment-water i n t e r f a c e over most of the study a r e a . T h i s o x i d i z e d l a y e r i s not n o t i c e a b l e i n the grab samples except i n those c o l l e c t e d over the c o n c r e t i o n l o c a l i t y . In t h i s area, t h i s l a y e r t h i c k e n s to s e v e r a l c e n t i m e t e r s and i n c l u d e s w i t h i n i t s depth a l a y e r o f coarse sand to c o b b l e - s i z e d m a t e r i a l . The o l i v e - g r e e n c o l o u r o f the wet sediments i s thought t o be due p r i m a r i l y t o the o r g a n i c content (Pantin, 1969). Reduced i r o n may add t o the o v e r a l l c o l o u r e f f e c t . F i g u r e 16 i l l u s t r a t e s the amount o f i r o n e x t r a c t e d i n p r e p a r a t i o n of samples f o r c l a y m i n e r a l a n a l y s i s , and F i g u r e 15 i l l u s t r a t e s the t o t a l carbon content i n these samples. Examination o f these f i g u r e s r e v e a l s a c l o s e r c o r r e l a t i o n between 53 t o t a l carbon content than e x t r a c t a b l e i r o n content w i t h the darker c o l o u r o f the sediments o f the lower b a s i n . When the samples are d r i e d a t toom temperature, the c o l o u r becomes l i g h t grey t o l i g h t green-grey. I I . T o t a l Carbon Content The t o t a l carbon content was determined f o r each o f the s u r f i c i a l samples c o l l e c t e d . F i g u r e 14 ( i n pocket) shows the d i s t r i b u t i o n o f carbon content over the e n t i r e study a r e a . F i g u r e 15 shows the carbon content i n comparison w i t h the weight o f c l a y s i z e p a r t i c l e s a long a l o n g i t u d i n a l p r o f i l e . In order t o convert a t o t a l carbon percentage i n t o an o r g a n i c matter percentage Trask recommends a m u l t i p l i c a t i o n f a c t o r o f 1.8 (Trask, 1938). F i g u r e 15 shows the t o t a l carbon content t o va r y approximately as the weight of c l a y - s i z e p a r t i c l e s . T h i s c o r r e l a t i o n i s l i k e l y due t o environmental energy f a c t o r s . The o r g a n i c m a t e r i a l has a d e n s i t y near t h a t o f sea water w i t h the m a j o r i t y o f p a r t i c = l e s having an e f f e c t i v e diameter i n the s i l t s i z e range. The r e s u l t w i l l be a very low s e t t l i n g v e l o c i t y . T h erefore, the maximum accumulation o f org a n i c d e b r i s w i l l occur i n the environment o f  55 minimal energy as w i l l the f i n e s t o f m i n e r a l p a r t i c l e s . The t r e n d i n the t o t a l carbon content i a a gradual i n c r e a s e w i t h i n c r e a s e i n d i s t a n c e from the head o f the i n l e t . T h i s t r e n d i s i n t e r - rupted i n the area o f the V-notch o f P a t r i c k S i l l as the notch r e p r e s e n t s a much h i g h e r energy environment than i t s surroundings. There are s e v e r a l p o s s i b l e e x p l a n a t i o n s f o r the observed t r e n d . Much o f the o r g a n i c d e b r i s i s thought t o o r i g i n a t e from phytoplankton. Thus, a lower p r o d u c t i v i t y o f the s u r f a c e waters over the upper b a s i n would g i v e the observed carbon d i s t r i b u t i o n p a t t e r n . However, another and perhaps more p l a u s - i b l e reason c o u l d be d i f f e r i n g f a c t o r s o f d i l u t i o n o f the o r g a n i c d e b r i s by sediment b e i n g added and d e p o s i t e d contemporaneously. G r a i n - s i z e analyses and o p t i c a l t u r b i d i t y data i n d i c a t e t h a t the r i v e r a t the head of the i n l e t i s the prime source o f sediment f o r upper J e r v i s I n l e t . Most o f the sediment i s d e p o s i t e d i n the upper b a s i n , thus d i l u t i n g the o r g a n i c d e b r i s more i n the upper than i n the lower b a s i n . The g r e a t e r water depth through which the o r g a n i c d e b r i s must s e t t l e i n the lower 56 b a s i n a p p a r e n t l y has l i t t l e e f f e c t on the amount o x i d i z e d b e f o r e b e i n g d e p o s i t e d on the b a s i n f l o o r . The d i f f e r e n c e i n t o t a l carbon d i s t r i b u t i o n between the upper and lower b a s i n s i s b e s t i l l u s - t r a t e d i n F i g u r e 14 ( i n p o c k e t ) . Most n o t i c e a b l e i s the r e l a t i v e l y c o n s t a n t d i s t r i b u t i o n i n the upper b a s i n v e r s u s the zonal d i s t r i b u t i o n i n the lower b a s i n . Over a l a r g e p a r t o f the upper b a s i n , the t o t a l carbon content i s i n the 2 - 3 % range w i t h e x c e p t i o n o f c e r t a i n nearshore areas and the slope a t the head o f the i n l e t . D i l u t i o n and p o s s i b l y lower p r o d u c t i v i t y probably account f o r the low v a l u e s at the head o f the i n l e t . The l o c a l i z e d , nearshore areas o f h i g h e r carbon content c o i n c i d e c l o s e l y w i t h log-booming grounds or streams which d r a i n areas p r e s e n t l y b e i n g logged. C o n s i d e r a b l e amounts o f s i m i l a r c oarse o r g a n i c d e b r i s are added from P r i n c e s s L o u i s a I n l e t t o the d e l t a on the J e r v i s I n l e t s i d e o f M a l i b u Rapids. The lower b a s i n can be d i v i d e d i n t o t h r e e a p p a r e n t l y d i s t i n c t zones on the b a s i s of carbon c o n t e n t . The nearshore zone has a low t o t a l carbon content ( <C 2%) and i s c o e x t e n s i v e w i t h the steep w a l l s . The i n t e r m e d i a t e zone, w i t h an average 57 c a r b o n c o n t e n t o f 2 - 3%, c o i n c i d e s w i t h t h e b r e a k i n s l o p e between t h e w a l l s and f l o o r , w h i l e t h e deep zone, w i t h a c a r b o n c o n t e n t o f 3 - 4% c o i n c i d e s w i t h t h e b a s i n f l o o r . The h i g h e r v a l u e s f o r s a m p l e s c o l l e c t e d w i t h i n t h e b a y a l o n g t h e s o u t h e a s t s h o r e may be due t o l o c a l a d d i t i o n o f o r g a n i c m a t e r i a l by s t r e a m s a n d / o r i n c r e a s e d p r o d u c - t i v i t y o f t h e more s h e l t e r e d s u r f a c e w a t e r s . I I I . F r e e I r o n C o n t e n t I n t h e p r e p a r a t i o n o f a sample f o r X - r a y d i f f r a c t i o n a n a l y s i s , i t i s n e c e s s a r y t o remove f r e e i r o n , t h e p r e s e n c e o f w h i c h c o u l d c a u s e f l u o r - e s c e n c e w i t h r e s u l t a n t l o s s o f s e n s i t i v i t y . The f i r s t s t a g e o f sample t r e a t m e n t was t h e d i s s o l u t i o n o f c a r b o n a t e m i n e r a l s by a d d i t i o n o f pH5 Sf s o d i u m a c e t a t e (NaOAc). O r g a n i c m a t e r i a l s were t h e n d e s - t r o y e d by t h e a d d i t i o n o f h y d r o g e n p e r o x i d e (H202)„ F r e e i r o n was e x t r a c t e d by a d d i n g s o d i u m d i t h i o n i t e t o t h e h e a t e d sample t o w h i c h a c i t r a t e b u f f e r h a d b e e n added, s t i r r i n g e v e r y two t o t h r e e m i n u t e s f o r a t o t a l o f f i f t e e n m i n u t e s . The s u p e r n a t a n t l i q u i d , as s e p a r a t e d b y c e n t r i f u g e , was d i l u t e d t o 1000 m l . and a n a l y z e d f o r i r o n b y a t o m i c a b s o r p t i o n . However, t h e s u p e r n a t a n t l i q u i d d e r i v e d f r o m t h e o r g a n i c 58 o x i d a t i o n step was o f t e n c o l o u r e d ranging from l i g h t g r e e n i s h t o d i s t i n c t red-brown i n d i c a t i n g the presence of i r o n . These s o l u t i o n s were saved and a n a l y z e d s i m i l a r l y t o those from the sodium d i t h i o n i t e treatment. The r e s u l t s o f the a n a l y ses are p l o t t e d i n F i g u r e 15 which shows the t o t a l f r e e i r o n as a sum o f t h a t e x t r a c t e d by the two t r e a t - ments. T h i s procedure r e s u l t s i n removal o f o n l y the adsorbed i r o n and w i l l not d e s t r o y w e l l c r y - s t a l l i z e d i r o n compounds nor e x t r a c t i r o n from i n t e r l a y e r p o s i t i o n s t h a t i t may occupy i n c e r t a i n m i n e r a l s such as c h l o r i t e . The c o n c e n t r a t i o n of the i r o n e x t r a c t e d by sodium d i t h i o n i t e i s r e l a t i v e l y c onstant w i t h d i s - tance from the head of the i n l e t , a v eraging about 0.35% (3500 ppm). The s t a t e o f t h i s i r o n i n the sediments i s probably as p o o r l y c r y s t a l l i n e p a r t i c u - l a t e i r o n oxides and as i r o n adsorbed t o c l a y m i n e r a l s . A r a t i o o f i r o n e x t r a c t e d by sodium d i t h i o n i t e t o percentage of c l a y - s i z e p a r t i c l e s ( a l l the samples had the same i n i t i a l weight) i n d i c a t e s a pronounced d e c r e a s i n g t r e n d from the head o f the i n l e t . Work done by Dr. E. V. G r i l l on metal content of sea waters from upper J e r v i s Nautical Miles 18 16 . 1 4 12 10 . 8 6 . . 4 . . . 2 0 FIG. IS IRON EXTRACTED DURING SAMPLE PREPARATION FOR X - R A Y ANALYSIS I n l e t shows the source o f p a r t i c u l a t e i r o n t o be the r i v e r a t the i n l e t head. I s o p l e t h s o f suspen- ded i r o n oxide content are approximately v e r t i c a l w i t h d e c r e a s i n g g r a d i e n t from the source. S i n c e the r a t i o curve tends t o approach a base l e v e l , an e x p l a n a t i o n f o r the shape o f the curve might be d i l u t i o n o f p a r t i c u l a t e i r o n w i t h d i s t a n c e from the source, w h i l e i r o n adsorbed by c l a y - s i z e p a r t i c l e s (of which approximately 70% are c l a y m i n e r a l s and micas) remains c o n s t a n t . The chemical s t a t e o f the i r o n w i t h i n the sediment e x t r a c t a b l e by hydrogen peroxide i s not known. P o s s i b l y i t was a s s o c i a t e d w i t h the o r g a n i c m a t e r i a l . Comparison o f F i g u r e 16 and F i g u r e 15 i n d i c a t e s a c o r r e l a t i o n between i r o n e x t r a c t e d by peroxide and t o t a l carbon content. The area w i t h sediments c o n t a i n i n g minimal e x t r a c t a b l e i r o n corresponds t o the manganese-iron c o n c r e t i o n l o c a l i t y on P a t r i c k S i l l . The t o t a l carbon content and the percentage o f c l a y - s i z e d p a r t i c l e s i s a l s o at a minimum because o f the hi g h e r energy o f the environment. I r o n c r u s t s recovered from the l o c a l i t y i n d i c a t e i r o n i s b e i n g p r e c i p i t a t e d on exposed rock s u r f a c e s . These c r u s t s w i l l be d e s c r i b e d l a t e r w i t h the manganese c o n c r e t i o n s . 61 IV. P a r t i c l e Morphology G r a n u l e - s i z e d and l a r g e r fragments, when present, showed a wide range i n degree o f roundness, v a r y i n g from angular t o sub-rounded. Evidences o f a g l a c i a l o r i g i n , such as scour marks and f a c e t i n g , were not confirmed on any o f the samples examined. D i s t i n c t faces on some rock fragments appeared t o r e p r e s e n t j o i n t i n g . M i n e r a l g r a i n s from the 500 - 300/u(1.0 - 1 . 5 0 ) and 88 - 63/u (3.5 - 4 0 ) f r a c t i o n s were examined by b i n o c u l a r microscope t o determine the gen e r a l shape and roundness and, i f p o s s i b l e , any t r e n d s . F i g u r e s 17 and 18 are photomicrographs o f the f r a c t i o n s examined f o r samples J-101, J-110, J-126 and J-19-67. Photograph J-126A shows a fragment o f a sponge s p i c u l e and photograph J-19-67-B shows rounded and p a r t i a l l y d e s s i c a t e d fragments which are thought t o be g l a u c o n i t e - m o n t m o r i l l o n o i d p e l l e t s . The shape o f many g r a i n s o f t e n r e f l e c t e d t h e i r g r a n i t i c o r i g i n . Quartz was g e n e r a l l y equidimen- s i o n a l as i n the assumed parent roc k s . Some o f the g r a i n s were elongate and v e r y angular and probably F i g u r e 17 a S t a t i o n J-101 (approx.11OX) Photomicrograph of m i n e r a l g r a i n s from very f i n e sand f r a c t i o n (63 t o 88yv.) b S t a t i o n J-101 (approx„60X) Photomicrograph of m i n e r a l g r a i n s from medium sand f r a c t i o n (350 to 500/u) c S t a t i o n J-110 (approx,110X) Photomicrograph o f m i n e r a l g r a i n s from very f i n e sand f r a c t i o n (63 t o 88/u)  F i g u r e 18 a S t a t i o n J-126 (approx.110 X)Photo- micrograph o f mineral g r a i n s from very f i n e send f r a c t i o n (63 to 88/u). The long p r i s m a t i c fragment i s a p o r t i o n o f a s p i c u l e from a s i l i c - eous sponge. b S t a t i o n J-126 (approx. 60 X) Photomicrograph o f min e r a l g r a i n s from medium sand f r a c t i o n (350 t o 500/u). Note a n g u l a r i t y and apparent c o n c o i d a l f r a c t u r i n g o f quartz g r a i n s . c S t a t i o n J-19-67 (approx.110 X) Photomicrograph o f m i n e r a l g r a i n s from a ve r y f i n e sand f r a c t i o n (63 t o 88/u) d S t a t i o n J-19-67 (approx.60 X) Photomicrograph of min e r a l g r a i n s from medium sand f r a c - t i o n (350 t o 500/u). Note rounded, p a r t i a l l y d e s s i c a t e d p e l l e t s i n lower h a l f o f photo- graph. These are t e n t a t i v e l y i d e n t i f i e d as g l a u c o n i t e - m o n t m o r i l l o n o i d p e l l e t s . 63 FIGURE 18 64 were formed by s h a t t e r i n g under h i g h s t r e s s . P l a g i o c l a s e and hornblende g r a i n s ranged from approximately equidimensional t o elongate or l a t h - l i k e . E x t e r n a l evidence o f a l t e r a t i o n was not common. Ge n e r a l l y , the m i n e r a l g r a i n s were angular i n d i c a t i n g e r o s i o n by p h y s i c a l processes f o l l o w e d s h o r t l y by d e p o s i t i o n w i t h l i t t l e or no re-working. Along the a x i s of the b a s i n s , however, subangular t o subrounded g r a i n s were found a t the i n l e t head and on the nodule l o c a l i t y . A t r a n s v e r s e s e c t i o n , j u s t above P r i n c e s s L o u i s a I n l e t i n d i c a t e d the c e n t r a l b a s i n sediments t o be b e t t e r rounded than the slope sediments. A s i m i l a r s e c t i o n along the c r e s t o f the s i l l i n d i c a t e d the o p p o s i t e i n t h a t a n g u l a r i t y i n c r e a s e d w i t h depth. A t h i r d t r a n s - v e r s e s e c t i o n , t h i s one a c r o s s the lower b a s i n , i n d i c a t e d more rounding w i t h depth. I f rounding of m i n e r a l g r a i n s i s o c c u r r i n g approximately i n s i t u , the areas w i t h g r e a t e s t c u r r e n t a c t i o n are the head o f the i n l e t and the nodule l o c a l i t y . 65 V. MINERALOGY 1. Granule and Larger S i z e M a t e r i a l ( y 2.0 mm) T h i n s e c t i o n s were c u t from c o b b l e - s i z e d f r a g - ments of each o f the major rock types present i n the sediments. I d e n t i f i c a t i o n o f m i n e r a l s w h i l e they were s t i l l members o f a rock-forming assemblage was much e a s i e r than when they were d i s c r e t e g r a i n s i n g r a i n mounts. Rocks o f approximately q u a r t z d i o r i t i c t o q u a r t z monzonitic composition accounted f o r 65 - 7 5% o f the g r a n u l e - s i z e d and l a r g e r m a t e r i a l recovered i n grab samples. G r a n i t e and minor pegmatite accounted f o r 5 - 15%, v o l c a n i c s ( u s u a l l y b a s a l t i c ) f o r 5 - 20%, and s l a t e s w i t h o c c a s i o n a l h o r n f e l s and am p h i b o l i t e fragments f o r 0 - 5 % . Hand specimens g e n e r a l l y appeared f r e s h and r e v e a l e d l i t t l e evidence o f a l t e r a t i o n i n the present marine environment. Where s u r f a c e a l t e r a t i o n was apparent, the mafic m i n e r a l s had been most n o t i c e a b l y a f f e c t e d . Whether t h i s a l t e r a t i o n o c c u r r e d i n the marine environment i s not known. A s u r f a c e c o l o u r a - t i o n , v a r i a b l e from l i g h t green t o dark red-brown was p a r t i c u l a r l y n o t i c e a b l e on l e u c o c r a t i c r o c k s . P o l i s h e d s e c t i o n e d r e v e a l e d t h a t t h i s s t a i n o c c u r r e d as a r i n d 66 and extended t o depths from 1 t o 5 mm. The s t a t e o f a l t e r a t i o n w i t h i n the s t a i n e d area was no more advanced than without. The red-brown s t a i n s may have been due t o absorbed i r o n oxides, whereas the green s t a i n s were p o s s i b l y of organ.i.c o r i g i n . T h i n sec- t i o n study i n d i c a t e d the s t a t e of a l t e r a t i o n of a m i n e r a l w i t h i n a fragment bore l i t t l e or no r e l a t i o n to d i s t a n c e from the fragment's s u r f a c e . In a t y p i c a l q uartz d i o r i t e cobble, s o d i c p l a g i o c l a s e (Abgo-70) accounted f o r about 60% o f the rock. The p l a g i o c l a s e was g e n e r a l l y subhedral to anhedral and o f t e n complexly twinned, although i n f o l i a t e d rocks, twinning was much l e s s n o t i c e a b l e . A m a j o r i t y o f g r a i n s showed l i t t l e or no a l t e r a t i o n . Quartz formed about 10% o f the rock and was u s u a l l y anhedral and i n t e r g r a n u l a r . E x t i n c t i o n p a t t e r n s were o f t e n wavy or undulatory. B i o t i t e was the p r i n - c i p a l mafic m i n e r a l . The l a t h e s were u s u a l l y i n t e r - t r a n u l a r and sometimes bent, Pleochroism was masked by the green or sometimes yel l o w - g r e e n c o l o u r . Micas ( i n p l a c e s ) showed sig n s of a l t e r a t i o n along c o n t a c t s w i t h other m i n e r a l s . Potassium f e l d s p a r o c c u r r e d i n minor q u a n t i t i e s . U n l i k e p l a g i o c l a s e , these g r a i n s 67 u s u a l l y showed some s i g n s o f a l t e r a t i o n . A l s o present were hornblende, sphene, z i r c o n , and magnetite. In some speciments, hornblende was the p r i n c i p a l mafic m i n e r a l . T y p i c a l l y the g r a i n s were sub h e d r a l . P l e o - chroism v a r i e d from yellow-green to blue-green^ In the more a c i d i c q u a r t z monzonite cobbles q u a r t z occupied about 45% of the s e c t i o n , K - f e l d s p a r 25%, p l a g i o c l a s e 25% and mafics and opaques 5%. The c o n s t i t u e n t m i n e r a l s d i s p l a y e d the same s p a t i a l r e l a - t i o n s . In the samples examined, a l t e r a t i o n o f f e l d - spar s p e c i e s was equal and most pronounced i n the cores o f the c r y s t a l s . The average composition o f the g r a n i t e s was 30 - 35% q u a r t z , 55 - 60% K - f e l d s p a r , and 5 - 10% p l a g i o c l a s e . The K - f e l d s p a r was o f t e n c o n s i d e r a b l y a l t e r e d . The v o l c a n i c rocks were b a s a l t i c . A specimen o f p o r p h y r i t i c b a s a l t c o n t a i n e d phenocrysts o f p l a g i o c l a s e (Anyg) a n < 3 pyroxene w i t h minor amounts o f o l i v i n e , b i o t i t e , magnetite, and hematite. The groundmass was dark brown t o b l a c k . In hand specimen the rock appeared a l t e r e d but t h i n s e c t i o n examina- t i o n d i d not v e r i f y t h i s . 68 i i H o r n f e l s fragments were b l a c k , f i n e - g r a i n e d , s c h i s t o s e and o f t e n porous. The c a v i t i e s were l i n e d w i t h l i m o n i t e and i n p l a c e s c o n t a i n e d p y r i t e . P l a g i o - c l a s e f e l d s p a r and/or quartz made up 55% o f the rock, hornblende 40%, and opaques 5%. Minor q u a n t i t i e s o f b i o t i t e and e p i d o t e were p r e s e n t . Hornblende c r y s t a l s were arranged i n p a r a l l e l t o s u b - p a r a l l e l alignment. There was l i t t l e a l t e r a t i o n o f e s s e n t i a l m i n e r a l s . The hand specimens o f a m p h i b o l i t e were f i n e g r a i n e d , s l i g h t l y f o l i a t e d , and dark green i n c o l o u r . Hornblen de comprised about 70%, p l a g i o c l a s e 25%, and qu a r t z 5% of the rock. A l t e r a t i o n was r e l a t i v e l y minor. 2. Sand S i z e M a t e r i a l (0.063 - 2.0 mm) W i t h i n the sand s i z e and c o a r s e r f r a c t i o n s , the mineralogy was determined f o r onl y the f i n e sands o f diameter range 62/u t o 125/u (40 to 30 ) . The i n d i v i d u a l g r a i n s w i t h i n t h i s f r a c t i o n were e s s e n t i a l l y monomineralic. However, the m a j o r i t y o f g r a i n s o f the h e a v i e r , mafic m i n e r a l s were i n t h i s s i z e range and t h e r e f o r e , the c a l c u l a t e d average composition w i l l be skewed towards the mafic m i n e r a l s . The mineralogy o f 16 samples, a l l c o l l e c t e d along the b a s i n axes, was determined. M i n e r a l content 6 9 o f the sediments along t r a n s v e r s e p r o f i l e s was not i n v e s t i g a t e d . The mi n e r a l percentages (by p o i n t count) are g i v e n i n Table 3. C r y s t a l l o g r a p h i c pro- p e r t i e s and degrees o f weathering were not t a b u l a t e d . The f o l l o w i n g i s a l i s t o f m i n e r a l s i d e n t i f i e d p e t r o g r a p h i c a l l y i n t h i n - s e c t i o n e d g r a i n mounts. E s s e n t i a l Accessory and Trace Quartz 'Epidote K - f e l d s p a r s Pyroxene P l a g i o c l a s e f e l d s p a r s Magnetite C h l o r i t e A p a t i t e B i o t i t e Sphene Amphibole ( p r i n c i p a l l y Garnet hornblende) Tourmaline Z i r c o n S t a . No. Quartz K F e l d s p a r P l a g . Indet. Mic C h l o r as . B l o t Amph 101 20.0 4. 5 35.5 7.9 2.9 0.9 15.9 102 23.8 4. 4 31.9 13.1 8.0 3.0 12.5 103 27.0 10. 4 29.0 7.5 7.1 2.2 7.4 104 32.6 9. 8 21.4 8.5 2.5 4.1 10.5 105 27.7 7. 2 21.5 8.5 13.1 4.3 12.2 108 19.3 2. 6 15.5 6.4 2.1 4.1 28.9 109 21.1 5. 1 42.1 8.9 9.1 4.8 8.2 110 24.8 8. 0 34.8 9.6 - „ - 118 18.9 8. 0 50.0 3.3 8.2 1.2 6.0 19-67 22.6 5. 7 41.5 9.3 9.9 2.2 5.0 126 23.8 6. 7 49.5 4.3 4.4 4.9 4.1 132 29.8 3. 6 46.1 1.6 2.5 10.4 3.1 138 20.8 7. 44.2 5.7 3.3 8.2 5.7 147 18.7 5. 5 4.1.6 2.5 13.4 13.4 2.3 155 23.5 12. 6 40.3 6.3 8.9 3.5 3.2 Table 3 Mineral Abundances i n F i ne 3 ai Pyroxene Epidote Magnetite A p a t i t e Unident. C l i n o . Ortho & M i s c . 0.8 0.5 6.6 1.3 3.0 1.0 0.5 3.1 0.1 0.1 3.1 0.5 0.3 2.9 0.4 - 5.2 0.5 0.1 3.0 0.3 0.6 4.4 0.1 ~ 3.7 1.0 0.1 1.9 0.8 2.0 12.7 1.2 0.4 4.9 1.8 0.3 1.7 1.1 0.2 1.0 0.2 1.0 0.3 0.7 - 2.1 0.1 0.2 1.0 0.7 - 1.9 0.2 0.4 0.3 0.3 0.1 1.0 - 0.3 0.5 0.2 - 1.0 - 0.4 1.7 0.3 - 2.6 _ 0.1 0.6 0.1 -- 2.0 - 0.2 0.3 0.2 - 0.9 F r a c t i on (by percent) o 71 From 4% t o 15% of the m i n e r a l g r a i n s counted were u n i d e n t i f i a b l e . Of these, about 7 5% appeared to be f e l d s p a r s but were a l t e r e d t o such an extent t h a t i d e n t i f i c a t i o n was u n c e r t a i n . Rock fragments were i n c l u d e d as unknown m i n e r a l s . However, the occurrence o f these, i n t h i s f r a c t i o n , was minor. An average composition o f the f i n e sand f r a c t i o n of the r e c e n t sediments would be: P l a g i o c l a s e 37% B i o t i t e 5% Quartz 24% Epidote 3% Amphibole 8% Pyroxene 1% K - f e l d s p a r 7% U n i d e n t i f i - 9% C h l o r i t e 6% a b l e rock fragments and opaques There was a marked s i m i l a r i t y o f p h y s i c a l and o p t i c a l p r o p e r t i e s of m i n e r a l s between the f i n e sand f r a c t i o n and the cobble f r a c t i o n . Most o f the coarse s u r f i c i a l sediments are thought t o have been d e r i v e d from Coast Range b a t h o l i t h i c rocks, as t h i s i s the only a v a i l a b l e source o f g r a n i t i c rock. Roddick (1965) d i s c u s s e d the Coast Range batho- l i t h o f the Vancouver North, Coquitlam and P i t t Lake map areas and gave an average composition o f the g r a n i t i c r o c k s . The average was an h-quartz d i o r i t e (where h denotes hornblende i s more abundant than b i o t i t e ) and had the f o l l o w i n g composition; 72 P l a g i o c l a s e 56% K - f e l d s p a r 1% Quartz 30% S e r i c i t e 1% Hornblende 7% Opaques 0.5% B i o t i t e 5% C h l o r i t e 0=5% Roddick's average composition does not c o r r e l a t e w i t h t h a t o f the marine sediment f r a c t i o n examined. However, s i n c e the mafic m i n e r a l s tended to be con- c e n t r a t e d w i t h i n t h i s f r a c t i o n , d i s c r e p a n c i e s would be expected. As the geology o f the study area i s unmapped, except on a reconnaissance b a s i s , the mineralogy o f rocks from p o s s i b l e sediment source areas i s not known. Perhaps the g r a n i t i c rocks o f the sediment source area tend t o be more a c i d i c than i n the area .studied by Roddick. The occurrence o f m i n e r a l s such as c h l o r i t e (6%) , e p i d o t e (3%) and pyroxenes (1%) i n these percentages i s probably an e x p r e s s i o n o f the presence o f p r e - b a t h o l i t h i c rocks which are mapped as o u t c r o p p i n g over most of the watershed o f upper J e r v i s I n l e t . The igneous rocks o f the Texada Group, as d e s c r i b e d by LeRoy (1908), are e x t e n s i v e l y a l t e r e d and o f t e n l a r g e percentages of the m i n e r a l s are secondary w i t h c a l c i t e , c h l o r i t e and e p i d o t e b e i n g the most common. 73 Since the sediment samples c o l l e c t e d f o r miner- a l o g i c a n a l y s i s were l i k e l y r e c e n t l y d e p o s i t e d , one would expect the i n f l u e n c e o f the surrounding out- c r o p p i n g rock t o be more pronounced. However, i f the p r e - b a t h o l i t h i c m a t e r i a l i n which the upper p a r t of the i n l e t i s i n c i s e d i s p r i m a r i l y s l a t e , then the diameter o f eroded p a r t i c l e s may be s m a l l e r than the range examined. Another p o s s i b i l i t y i s t h a t the extent o f the r o o f pendant o f p r e - b a t h o l i t h i c m a t e r i a l may not be n e a r l y as g r e a t as p r e s e n t l y mapped. However, assuming the gross geology, as mapped t o date, t o be reasonably c o r r e c t , the source o f sand s i z e and l a r g e r m a t e r i a l b e i n g d e p o s i t e d i n the i n l e t must be r e l i c t P e l i s t o c e n e d e p o s i t s undergoing reworking i n both t e r r e s t r i a l and marine environments. The presence o f s i l l s prevents l o s s o f a l l but the ve r y f i n e s t o f m a t e r i a l c a r r i e d i n t o the i n l e t . S e v e r a l trends were noted w i t h i n m i n e r a l g r o u p s . ( F i g u r e 19). B i o t i t e , which g r a d u a l l y i n c r e a s e s i n abundance from the head o f the i n l e t , was u s u a l l y a dark green c o l o u r . However, over the s i l l , a red-brown v a r i e t y predominates. Whether t h i s e f f e c t i s goochemic-a-l or an e x p r e s s i o n of present and/or past sedimentation p a t t e r n s i s not  75 known. From the head of the i n l e t t o S t a t i o n J-118, hornblende was the onl y amphibole p r e s e n t . However, from J-118 to the end of the study area, t r e m o l i t e - a c t i n o l i t e was a l s o found, although never w i t h the same abundance as hornblende. Even.though sediment i s b e i n g added t o the i n l e t elsewhere than a t the head, the r e l a t i v e l y uniform sediment mineralogy from S t a t i o n J-110 down the i n l e t i n d i c a t e s most sediment sources have a s i m i l a r m i n e r a l o g i c composition. The e x c e p t i o n t o the approximately uniform t r e n d i n mineralogy occurs a t the head o f the i n l e t between S t a t i o n s J-101 and J-110. Here i t appears t h a t slumping p l a y s a major r o l e i n sediment d i s t r i - b u t i o n . The break i n slope o c c u r r i n g a t J-108 corresponds w i t h a marked i n c r e a s e i n heavy m i n e r a l s and a decrease i n micaceous m i n e r a l s . 3) C l a y S i z e M a t e r i a l M i n e r a l o g i c analyses o f c l a y s i z e p a r t i c l e s were made f o r each o f the samples f o r which the mineralogy o f the sand and cobble f r a c t i o n was d e t e r - mined. Table 5 g i v e s the r e s u l t s o f these a n a l y s e s . I n t e r p r e t a t i o n o f abundances from d i f f r a c t o g r a m s was made w i t h r e f e r e n c e t o t h r e e sample i n t e r p r e t a t i o n s 76 made by Dr. L. M. L a v k u l i c h (Department o f S o i l S c i e n c e s , U n i v e r s i t y o f B r i t i s h Columbia.) The f o l l o w i n g s c a l e o f abundance was used: 5 Dominant 65 - 100% 4 Major 35 - 65% 3 Minor 10 - 35% • 2 Trace 0 - 10% 1 ^7one Clay m i n e r a l i d e n t i f i c a t i o n was based on X-ray d i f f r a c t i o n data o n l y . The r e l a t i v e amounts o f Fe, Mg, and A l .in the c h l o r i t e s was based on d i f f r a c t i o n p a t t e r n s g i v e n by Weaver (1958). Some peaks which appeared on the d i f f r a c t o g r a m s c o u l d not be i d e n t i - f i e d , but the magnitude o f these i n d i c a t e d t r a c e abundances. A l i s t (Table 4) of the r e c o g n i z e d m i n e r a l s p e c i e s and t h e i r |po i j peaks ( i n Angstroms) a c c o r d i n g t o treatment appears on the f o l l o w i n g page. MINERAL K K 300°C K 500°C Mg Mg & G l y c e r o l C h l o r i t e 14 14.2 14.2 14.2 14.2 1 1 l i t e 10 10 10 10 10 V e r m i c u l i t e 10-13 10 10 14-15 14 Montmo ri 1 1 o n i t e 12-14 10 10 12.8-14 17-18 I l i i t e - m o n t m o r i l l o n i t e 10-14 10 10 10-14 10-18 111ice - v e r m i c u l i t e 10-13 10 10 10-15 10-14 1 1 1 i t e - c h l o r i t e 10-14 10-14 10-14 10--14 10-14 P l a g i o c l a s e 3.18 3.18 3.18 3.18 3.18 Quartz 3.3 3.3 3.3 3.3 3.3 Amphibole (hornblende) 8.40 8.40 8.40 8.40 8.40 K - f e l d s p a r 3.24 3.24 3.24 3.24 3.24 Table 4 !00l| Peaks ( i n Angstroms) of M i n e r a l s i n Clay S i z e F r a c t i o n 78 P l a g i o c l a s e f e l d s p a r , q u a r t z and amphibole ( p r i n c i p a l l y hornblende) were present i n n e a r l y c o n s t a n t p r o p o r t i o n s f o r the l e n g t h of the i n l e t . K - f e l d s p a r o c c u r r e d as a t r a c e m i n e r a l i n con- s i d e r a b l y l e s s e r q u a n t i t i e s than p l a g i o c l a s e and q u a r t z . As w i t h some o f the m i n e r a l s i n the c o a r s e r f r a c t i o n s , K - f e l d s p a r content i n c r e a s e s s i g n i f i c a n t l y at S t a t i o n J-118 where the i n f l u - ence o f P r i n c e s s L o u i s a I n l e t would be expected. S e v e r a l i n t e r e s t i n g trends were noted i n the c l a y m i n e r a l abundances. There i s i n s u f f i c - i e n t i n f o r m a t i o n t o determine whether or not the observed trends are geochemically s i g n i f i c a n t . Many i n v e s t i g a t o r s (Grim, 1968) have concluded t h a t v a r i a t i o n s i n s e t t l i n g r a t e s o f c l a y m i n e r a l s p e c i e s are adequate t o e x p l a i n v a r i a t i o n s i n abundances i n s i t u a t i o n s l i k e upper J e r v i s I n l e t where t h e r e i s a dominant sediment source. With i n c r e a s e i n s a l i n i t y the s e t t l i n g v e l o c i t y o f i l l j . t e and k a o l i n i t e has been found t o i n c r e a s e r a p i d l y w h i l e t h a t o f the s m e c t i t e s (e.g. mont- m o r i l l o n i t e ) i s l i t t l e a f f e c t e d . The most n o t i c e a b l e t r e n d i s the d i s a p p e a r - ance o f m o n t m o r i l l o n i t e and i l l i t e - m o n t m o r i l l o n i t e 7 9 i n t e r g r a d e by S t a t i o n J-103, i . e . s h o r t l y a f t e r the m a t e r i a l e n t e r s the marine environment. With the disappearance of these s p e c i e s , v e r m i c u l i t e and an i l l i t e - v e r m i c u l i t e i n t e r g r a d e appear. The i l l i t e - v e r m i c u l i t e i n t e r g r a d e occurs w i t h an approximately constant abundance f o r the remaining l e n g t h of the study a r e a . V e r m i c u l i t e g r a d u a l l y i n c r e a s e s i n abundance u n t i l , on the s i l l , i t becomes the dominant c l a y m i n e r a l . For the remain- i n g samples analyzed, v e r m i c u l i t e remains one of the dominant or near^dominant types. The o v e r a l l t r e n d i s thus an i n c r e a s e i n v e r m i c u l i t e w i t h d i s t a n c e from the head o f the i n l e t w i t h the i n c r e a s e b e i n g accentuated on the s i l l . The only other type t r e n d noted was the appearance o f an i l l i t e - c h l o r i t e i n t e r g r a d e a t S t a t i o n J-118. T h i s i n t e r g r a d e occurs i n most samples taken f a r t h e r down the i n l e t , but only i n t r a c e amounts. The two dominant c l a y m i n e r a l s are Fe and Fe-Mg c h l o r i t e and i l l i t e . There i s no n o t i c e a b l e t r e n d i n abundance of these. M o n t m o r i l l o n i t e i s a dominant c l a y m i n e r a l i n sediments c o l l e c t e d from the i n l e t head. T h e r e f o r e , i f d i f f e r e n t i a l s e t t l i n g o f the c l a y m i n e r a l 80 s p e c i e s i s o c c u r r i n g , i t i s l i k e l y t o be doing so on a s m a l l e r s c a l e than on which upper J e r v i s I n l e t was sampled. The apparent r a p i d d i s a p p e a r - ance o f m o n t m o r i l l o n i t e and i l l i t e - m o n t m o r i l l o n - i t e intergrcide w i t h d e p o s i t i o n i n the s a l i n e i n l e t environment suggests t h a t potassium and magnesium are b e i n g absorbed from sea water by the m o n t m o r i l l o n i t e . A b s o r p t i o n of these e l e - ments c o l l a p s e s the m o n t m o r i l l o n i t e s t r u c t u r e r e s u l t i n g i n the formation o f i l l i t e and c h l o r i t e . 81 TABLE 5 RELATIVE ABUNDANCES OF CLAY MINERAL SPECIES J-101 I l l i t e 3-4 Fe c h l o r i t e 3-4 Il l i t e - m o n t m o r . 3-4 M o n t m o r i l l o n i t e 3 Amphibole 2 P l a g i o c l a s e 2 Quartz 2 J-103 Fe C h l o r i t e 3-4 I l l i t e 3-4 V e r m i c u l i t e 3 I l l i t e - v e r m i c . 3 P l a g i o c l a s e 2-3 Quartz 2-3 Amphibole 2 J-105 Fe c h l o r i t e 3-4 I l l i t e 3-4 V e r m i c u l i t e 3-4 I l l i t e - v e r m i c . 3 P l a g i o c l a s e 2 Quartz 2 Amphibole 2 J-109 Mg-Fe c h l o r i t e 4 I l l i t e 3-4 V e r m i c u l i t e 3 I l l i t e - v e r m i c . 3 P l a g i o c l a s e 2 Quartz 2 Amphibole 2 I l l i t e - c h l o r i t e 2 J-118 Mg-Fe c h l o r i t e 3-4 I l l i t e 3-4 V e r m i c u l i t e 3-4 I l l i t e - v e r m i c . 3 P l a g i o c l a s e 2 Quartz 2 Amphibole 2 I l l i t e - c h l o r i t e 2 J-102 Fe c h l o r i t e 4 Il l i t e - m o n t m o r . 3 I l l i t e 3 M o n t m o r i l l o n i t e 3 P l a g i o c l a s e 2 Amphibole 2 Quartz 2 J-104 Mg-Fe c h l o r i t e 4 I l l i t e 3-4 V e r m i c u l i t e 3 V e r m i c . - i l l i t e 3 P l a g i o c l a s e 2 Quartz 2 Amphibole 2 J-108 Fe c h l o r i t e 4 I l l i t e 3-4 V e r m i c u l i t e 3 I l l i t e - v e r m i c . 3 P l a g i o c l a s e 2 Quartz 2 Amphibole 2 J-110 Mg-Fe c h l o r i t e 3-4 V e r m i c u l i t e 3-4 I l l i t e - v e r m i c . 3-4 I l l i t e 3 P l a g i o c l a s e 2 Quartz 2 Amphibole 2 J-123 Mg-Fe c h l o r i t e 4 I l l i t e 3-4 V e r m i c u l i t e 3-4 I l l i t e - v e r m i c . 2-3 I l l i t e - c h l o r i t e 2 Quartz 2 P l a g i o c l a s e 2 Amphibole 2 82 TABLE 5 (contd.) J-147 V e r m i c u l i t e 4 J - 19-67 V e r m i c u l i t e 3- 4 Mg Fe c h l o r i t e 3 Fe c h l o r i t e 3-•4 I l l i t e 3 I l l i t e 3 Illite-vermic„ 3 I l l i t e - v e r m i c B 2- 3 Quartz 2 Quartz 2 Illite«chlorite 2 P l a g i o c l a s e 2 P l a g i o c l a s e 2 Amphibole 2 Amphibole' 2 I l l i t e - c h l o r i t e 2 Fe c h l o r i t e 4 J -•138 Fe c h l o r i t e 3-•4 V e r m i c u l i t e 3--4 I l l i t e 3-•4 I l l i t e 3 V e r m i c u l i t e 3 I l l i t e - v e r m i c . 2--3 Illite-vermic„ 2-•3 Quartz 2 I l l i t e - c h l o r i t e 2 P l a g i o c l a s e 2 Quartz 2 Amphibole 2 P l a g i o c l a s e 2 I l l i t e - c h l o r i t e 2 Amphibole 2 V e r m i c u l i t e 4 J -•155 Fe c h l o r i t e 3-•4 Mg Fe c h l o r i t e 3--4 I l l i t e 3-•4 I l l i t e 3--4 V e r m i c u l i t e 3-•4 I l l i t e - v e r m i c . 2--3 I l l i t e - v e r m i c . 2-•3 P l a g i o c l a s e 2 Quartz 2 Quartz 2 P l a g i o c l a s e 2 Amphibole 2 Amphibole 2 I l l i t e - c h l o r i t e 2 I l l i t e - c h l o r i t e 2 83 V I . GRAIN SIZE DISTRIBUTION The g r a i n s i z e d i s t r i b u t i o n and co r r e s p o n d i n g parameters were c a l c u l a t e d w i t h a computer program developed by Dr. A. J . S i n c l a i r o f the Department o f Geology, U n i v e r s i t y o f B r i t i s h Columbia. C a l c u l a t i o n s were based on a cumulative curve p l o t t e d w i t h a r i t h - metic o r d i n a t e s and developed by j o i n i n g s u c c e s s i v e data p o i n t s w i t h s t r a i g h t l i n e s . A minimum g r a i n s i z e was needed i n the program and was a r b i t r a r i l y s e t a t 0.06/U ( 14 0 ) The f o l l o w i n g i s a l i s t o f parameters c a l c u l a t e d f o r each sample. Mean A r i t h m e t i c Graphic (Folk) Graphic (Inman) Standard D e v i a t i o n A r i t h m e t i c Graphic (Folk) Graphic (Inman) I n c l u s i v e Graphic Phi Q u a r t i l e S o r t i n g C o e f f i c i e n t ( T r a s k ) Skewness Moment Phi Q u a r t i l e Graphic I n c l u s i v e Graphic K u r t o s i s Moment Graphic Transformed Graphic Parameters used f o r i n t e r p r e t a t i o n i n t h i s study 84 were the g r a p h i c mean ( F o l k ) , g r a p h i c standard d e v i a t i o n ( F o l k ) , i n c l u s i v e g r a p h i c skewness, and g r a p h i c k u r t o s i s . These parameters were the more e f f i c i e n t w i t h r e s p e c t t o the average g r a i n s i z e d i s t r i b u t i o n o f the sediment analyzed and the l a b o r a - t o r y methods used. The m a j o r i t y of the sediment i n upper J e r v i s I n l e t c o n t a i n s abundant m a t e r i a l i n the s i l t and c l a y s i z e f r a c t i o n s . Hydrometer analyses were taken as f a r as 0.98/u (10 0) wit h the r e s u l t t h a t a c o n s i d e r a b l e percentage o f the m a t e r i a l (up t o 34%) was not d i r e c t l y analyzed, i . e . , was o f diameter l e s s than 0.98/u. The u s e f u l n e s s o f g r a i n s i z e parameters i n such an environment i s t h e r e f o r e suspect. However, c e r t a i n trends d i d show up i n l o n g i t u d i n a l p r o f i l e s . The g r a p h i c mean as proposed by Fol k r e f l e c t s the average p a r t i c l e diameter o f a sediment. S i n c e the 0 diameter i s d e f i n e d as - l o g 2 ( p a r t i c l e diameter i n m i l l i m e t e r s ) a t r e n d showing an i n c r e a s e i n 0 v a l u e would i n d i c a t e a decrease i n p a r t i c l e s i z e . T h i s parameter i s c a l c u l a t e d from the f o l l o w - i n g equations Folk and Ward (1957) Mg= 016 + 050 + 084 where 016, 050 and 084 are the 0 v a l u e s taken from 85 a cumulative curve f o r the a p p r o p r i a t e p e r c e n t i l e s . However, the gr a p h i c mean g i v e s no i n d i c a t i o n o f the range of the g r a i n s i z e diameters and f o r i n t e r p r e - t i v e purposes the i n c l u s i v e g r a p h i c standard d e v i a - t i o n must be c o n s i d e r e d s i m u l t a n e o u s l y . The equation o f t h i s parameter, which g i v e s the " s o r t i n g " or d i s - p e r s i o n o f the p o p u l a t i o n i s t Folk and Ward (1957) Oi = (084-016) - (095-05) 4 6.6 The i n c l u s i v e g r a p h i c skewness and the g r a p h i c k u r t o s i s should a l s o be c o n s i d e r e d as a p a i r . The equations o f these parameters a r e : Folk and Ward (1957) Skewness S,,= 084-016+2050 + 095-05-2050 2(084-016) 2(095-05) K u r t o s i s K_ = 095 - 05 2.44(07 5-02 5) Skewness and k u r t o s i s are measures of non- n o r m a l i t y of a d i s t r i b u t i o n . The degree o f asymmetry i s measured by the skewness parameter. A n e g a t i v e v a l u e i n d i c a t e s a d i s t r i b u t i o n curve asymmetric t o the l e f t ( i . e . excess o f coarse m a t e r i a l ) , w h i l e a p o s i t i v e v a l u e i n d i c a t e s asymmetry t o the r i g h t , ( i . e . excess o f f i n e m a t e r i a l ) . A skewness v a l u e i s a pure number and the a b s o l u t e l i m i t s are -1.00 and +1.00. 86 K u r t o s i s i s a measure of peakedness o f a curve, and i s a r a t i o between s o r t i n g i n the t a i l s and s o r t i n g i n the c e n t r a l p o r t i o n . Low v a l u e s f o r k u r t o s i s ( i . e . 0.9) i n d i c a t e b e t t e r s o r t i n g i n the t a i l s than c e n t r a l p o r t i o n . A d i s t r i b u t i o n w i t h low k u r t o s i s i s o f t e n bimodal. As w i t h skewness, a k u r t o s i s v a l u e i s a pure number. The abs o l u t e l i m i t s o f the measure a +0.41 and i n f i n i t y , but most samples f a l l i n the 0.60 t o 5.0 range (Folk 1961). F i g u r e 20 ( i n pocket) shows the d i s t r i b u t i o n o f sediments a c c o r d i n g t o g r a i n s i z e based on Shepard's (1954) c l a s s i f i c a t i o n . F i g u r e 21 ( i n pocket) shows the c l a y s i z e p a r t i c l e d i s t r i b u t i o n i n upper J e r v i s I n l e t and F i g u r e s 22 and 23 are l o n g i t u d i n a l pro- f i l e s o f g r a i n s i z e d i s t r i b u t i o n parameters. Frequency curves p l o t t e d from the g r a i n s i z e a nalyses i n d i c a t e t h a t the s u r f i c i a l sediments i n upper J e r v i s I n l e t can g e n e r a l l y be d i v i d e d i n t o two dominant modes. The co a r s e mode u s u a l l y f a l l s i n the 250 t o 63/u (20 t o 40) range, w h i l e the f i n e r mode i n the 16 t o 4^u (60 to 80) range. These ranges r e p r e s e n t the f i n e t o v e r y f i n e sands and Gutico! Miles i3 • ct ion 4- o Q 3- O or < a 2-1 8-\ < U J 4 - 165 152 147" 146 145' 144 I 138 !9L67I32 I 126 I25 ' i24 \iz MEAN STANDARD DEVIATION - 2 6 0 - 2 8 0 - 3 0 0 -320 - 3 4 0 FIGURE 22 MEAN AND STANDARD DEVIATION OF GRAIN SIZE . OF SURFICIAL SEDIMENTS ALONG AXiS ^ OF UPPER JERVIS INLET FIGURE 2 3 KURTOSIS AND SKEWNESS PARAMETERS OF SURFICIAL SEDIMENTS' ALONG AXIS OF UPPER JERVIS INLET § 39 and medium s i l t s to c l a y s r e s p e c t i v e l y . The pa r a - meters presented i n F i g u r e s 22 and 23 can be inter-, p r e t e d i n terms of v a r y i n g p r o p o r t i o n s o f these two modes. Most n o t i c e a b l e on the map showing sediment type d i s t r i b u t i o n was the uniform decrease i n average p a r t i c l e diameter w i t h d i s t a n c e from the head o f the i n l e t w i t h i n the upper b a s i n . The cumulative . curves and histograms, i n F i g u r e 24 a l s o i l l u s t r a t e d t h i s . The p a r t i c l e s i z e d i s t r i b u t i o n o f sample J - l l l r e p r esented an approximate average f o r the upper b a s i n (0.9% sand, 51.9% s i l t , 47.2% c l a y ) . For the sediment c o l l e c t i n g on the f l o o r o f the upper b a s i n , the g r a p h i c mean ( i n jZf v a l u e s ) i n c r e a s e d w h i l e the i n c l u s i v e g r a p h i c standard d e v i a t i o n r e - mained approximately c o n s t a n t . O v e r a l l , k u r t o s i s f o l l o w e d a s l o w l y d e c r e a s i n g t r e n d , and skewness an approximately c o n s t a n t t r e n d . The p r i n c i p a l source o f sediment w i t h i n the upper b a s i n would t h e r e f o r e be i n t e r p r e t e d as being the r i v e r and r i v e r d e l t a at the i n l e t head. However, an a p p r e c i a b l e amount of m a t e r i a l i s b e i n g added from P r i n c e s s L o u i s a I n l e t and the d e l t a i c d e p o s i t formed a l o n g the shore FIGURE 24 LONGITUDINAL PROFILE . OF QUEENS REACH - CUMULATIVE AND FREQUENCY CURVES OF SURFICIAL SEDIMENTS 91 o f J e r v i s I n l e t a t the p o i n t where the two i n l e t s are connected (Malibu R a p i d s ) . F i g u r e s 22 and 23 i n d i c a t e t h a t a d d i t i o n o f f i n e sand and s i l t i s o c c u r r i n g i n the v i c i n i t y o f S t a t i o n J-117. The mineralogy of the m a t e r i a l b e i n g added c l o s e l y resembled t h a t o f the sediment o r i g i n a t i n g from the i n l e t head, probably i n d i c a t i n g a common g l a c i a l o r i g i n . On an ebb t i d e , a v i g o r o u s t i d a l c u r r e n t (maximum v e l o c i t y 10-12 knots, where 10 knots i s e q u i v a l e n t t o 520 cm/sec.) flows from P r i n c e s s L o u i s a I n l e t i n t o J e r v i s I n l e t . T h i s t i d a l j e t , a t the p o i n t o f maximum v e l o c i t y , would be s u f f i c i e n t t o carry cobble or b o u l d e r - s i z e d m a t e r i a l . Even though the v e l o c i t y would a t t e n u a t e r a p i d l y once the water spread i n t o J e r v i s I n l e t , c o n s i d e r a b l e reworking o f the d e l t a i c sediments would l i k e l y occur. The f i n e r sands and s m a l l e r m a t e r i a l would be d e p o s i t e d as f o r e s e t beds or c a r r i e d i n suspen- s i o n by the weak e s t u a r i n e c i r c u l a t i o n and d e p o s i t e d elsewhere. Subsequent slumping o f the d e l t a would c a r r y the f i n e sands t o the depths o f the b a s i n s . Figure. 25 presents the cumulative and frequency curves f o r a t r a n s v e r s e s e c t i o n o f Queen's Reach a t a p o i n t above Malibu Rapids. The abundance o f the Nautical Miles FIGURE 25 TRANSVERSE PROFILE OF QUEENS REACH - CUMULATIVE AND FREQUENCY CURVES OF SURFICIAL SEDIMENTS Bottom Photographs The s c a l e of the photographs depends on the camera t o sea f l o o r d i s t a n c e . Where present, the compass assembly can be used as a s c a l e i n d i c a t o r . The diameter o f the compass dome i s 3 i n . (7.55 cm.) and the l e n g t h o f the vane i s 10 i n . (25 cm.) On an average, the photographs cover an area o f about 3 f e e t by 4 f e e t (approx. 1 m. x 1.3 m). F i g u r e 26 a Note hummocky microtopography. Whether t h i s i s due to the presence of animals or t o deposit i o n ^ processes i s not known. b Note shadow o f compass. T h i s d i f f e r e n t aspect o f the micro- topography i s l i k e l y due t o d i f f e r e n c e i n camera angle. Figure.27 a Note the skate p a r t i a l l y c o ncealed i n the bottom s e d i - ments. Hummocky microtopo- graphy s t i l l prominent. b A l l photographs approx. 1/8 t r u e s c a l e 33  95 coarse mode decreases w i t h depth, w h i l e t h a t o f the f i n e r mode i n c r e a s e s . F i g u r e s 26 and 27 are bottom photographs teken at S t a t i o n J-126. These were taken at a depth o f 130 fathoms (350 meters) which i s the maximum depth i n the upper b a s i n . Each photograph covers an area measuring about 3 by 4 f e e t , (1 by 1.3 meters). The microtopography appears hummocky. The o r i g i n o f these hummocks i s not known, but animals o b v i o u s l y have some e f f e c t as shown by F i g u r e 27a i n which a skate had j u s t p a r t i a l l y b u r i e d i t s e l f i n the s e d i - ment. However, photographs taken i n an area where slumping i s almost c e r t a i n l y o c c u r r i n g ( F i g u r e s 34 and 35) show a s i m i l a r topography. Thus,slumping i s a l s o a p o s s i b l e e x p l a n a t i o n f o r the topography p i c t u r e d . Photographs of b e t t e r q u a l i t y , c o v e r i n g a l a r g e r area and p r e f e r a b l y as s t e r e o p a i r s would be v e r y advantageous t o such . i n t e r p r e t a t i o n . Perhaps the most i n t e r e s t i n g area, even from a se d i m e n t o l o g i c p o i n t o f view, i s P a t r i c k S i l l s The medial d e p r e s s i o n or V-notch and the f l a n k s o f the s i l l i n l i n e w i t h the notch are a p p a r e n t l y areas o f sediment reworking. F i g u r e 28 i l l u s t r a t e s how the sediment c h a r a c t e r i s t i c s change i n p a s s i n g from the upper t o the lower b a s i n over P a t r i c k S i l l . The FIGURE 28 LONGITUDINAL PROFILE OF LOWER QUEENS REACH AND UPPER PRINCESS ROYAL REACH CUMULATIVE AND FREQUENCY CURVES OF SURFICIAL SEDIMENTS 97 sediments c o l l e c t e d above and below the s i l l ( S t a t i o n s J-125 and J-146 r e s p e c t i v e l y ) are very s i m i l a r . The. c o n c r e t i o n l o c a l i t y ( S t a t i o n J-19-67) sediments have a mean diameter o f 63/u (40) w i t h a h i g h standard d e v i a t i o n . Skewness i s h i g h and k u r t o s i s i s low. Apparently a c u r r e n t i s winnow- in g the sediment, l e a v i n g a l a g d e p o s i t o f m a t e r i a l w i t h a dominant mode i n the 250 t o 125/u (20 t o 30) range. T h i s sediment i s n o t i c e a b l y c o a r s e r than any other c o l l e c t e d i n the study area from depths g r e a t e r than 100 fathoms (183 meters). The photo- graphs i n F i g u r e s 29 and 30 were taken near the nodule l o c a l i t y . The rock o u t - c r o p p i n g i n F i g u r e 29a may be a g l a c i a l l y r a f t e d boulder, but appears to be bedrock. The c u r r e n t d i r e c t i o n would be per- p e n d i c u l a r t o the plane i n which the gorgonian c o r a l i s growing. F i g u r e s 29b and 30a show the l a g d e p o s i t and F i g u r e 30b a more t y p i c a l bottom sediment, near but not i n the medial d e p r e s s i o n , i n d i c a t i n g the maximum i n t e n s i t y o f the c u r r e n t i s c o n f i n e d t o the medial d e p r e s s i o n . Sediments c o l l e c t e d on the s i l l f l a n k s a t S t a t i o n J-131 and J-143 were s i m i l a r i n g r a i n s i z e F i g u r e 29 a Bedrock or l a r g e b o u l d e r i n v i c i n i t y o f c o n c r e t i o n l o c a l - i t y . Low r a t e s o f sediment d e p o s i t i o n i n t h i s area a l l o w animal growth. Plane of gor- gonian c o r a l i n background i s normal t o c u r r e n t d i r e c t i o n , (approx. 1/8 X) b Lag d e p o s i t i n area o f con- c r e t i o n l o c a l i t y . Note abund- ance o f squat l o b s t e r s , (approx. 1/8 X) i  Photograph taken on s l o p e o f medial d e p r e s s i o n . A low sedimentation r a t e i s i n d i c a t e d by the presence o f s i l i c e o u s sponges e t c . (approx. 1/8 1Q Photograph taken on slope o f medial d e p r e s s i o n t o the east o f the c o n c r e t i o n l o c a l i t y . A low sedimenta- t i o n r a t e i s i n d i c a t e d as w e l l as minor i n f l u e n c e o f bottom c u r r e n t s (approx.1/8X)  100 d i s t r i b u t i o n . I f thr= o r i g i n o f the dominant mode i n the 250 to 125^/u ( 2 0 t o 3 0 ) range were the c r e s t of the s i l l , a c u r r e n t v e l o c i t y of at l e a s t 25 cm/ sec. must flow i n the medial d e p r e s s i o n . Slumping may c a r r y the m a t e r i a l d e r i v e d from the s i l l t o the f l a n k s as the c u r r e n t v e l o c i t y w i t h i n the medial d e p r e s s i o n probably would not be maintained over the f l a n k s . The two-way a c t i o n o f the c u r r e n t through the d e p r e s s i o n i n d i c a t e d by sediment parameters and s i z e d i s t r i b u t i o n curves, suggests a t i d a l o r i g i n . However, c u r r e n t a c t i o n i n the south e a s t e r l y d i r e c - t i o n a p p a r e n t l y i s more pronounced. Cumulative and frequency curves p l o t t e d f o r sediments c o l l e c t e d on the s i l l a l ong a l i n e t r a n s - v e r s e to the medial d e p r e s s i o n are presented i n F i g u r e 31. Most n o t i c e a b l e i s the v e r y poor s o r t i n g , e s p e c i a l l y f o r samples c o l l e c t e d on e i t h e r s i d e of the medial d e p r e s s i o n . The deeper the sample s t a t i o n , the more dominant i s the coarse f r a c t i o n . T h i s t r e n d i s the r e v e r s e of t h a t p i c t u r e d i n F i g u r e 25. The very poor s o r t i n g and wide range o f g r a i n s i z e s i n d i c a t e s t h a t the s u r f i c i a l sediments of the s i l l are probably o f a g l a c i a l o r i g i n and, w i t h e x c e p t i o n /OJ 29i FIGURE 31 TRANSVERSE SECTION OF QUEENS REACH (OVER PATRICK SILL) CUMULATIVE AND FREQUENCY CURVES OF SURFICIAL SEDIMENTS .102 o f those, s e d i m e n t s i n t h e m e d i a l d e p r e s s i o n , have b e e n l i t t l e a f f e c t e d s i n c e i n i t i a l d e p o s i t i o n i n P l e i s t o c e n e t i m e s The d i s t r i b u t i o n c h a r a c t e r i s t i c s o f s e d i m e n t s c o l l e c t e d a l o n g t h e a x i s o f P r i n c e s s R o y a l Reach ( l o w e r b a s i n ) a r e p r e s e n t e d i n F i g u r e 32. The two d o m i n a n t s e d i m e n t modes a p p a r e n t on a s i m i l a r l o n g i - t u d i n a l p r o f i l e f o r t h e u p p e r b a s i n ( F i g u r e 24) a r e a p p a r e n t i n s e d i m e n t s from t h e l o w e r b a s i n . However, t h e m a t e r i a l c o l l e c t i n g i n t h e l o w e r b a s i n i s o r i g - i n a t i n g f r o m many s o u r c e s , e a c h w i t h a l o c a l i z e d e f f e c t , w hereas t h a t i n t h e u p p e r b a s i n comes from one d o m i n a n t s o u r c e . T h i s i s e v e n more a p p a r e n t i n F i g u r e 20 ( i n p o c k e t ) . E v i d e n c e o f s l u m p i n g was o b t a i n e d f r o m S t a t i o n J-160. F i g u r e 33 p r e s e n t s c u m u l a t i v e and f r e q u e n c y c u r v e s f o r a s e c t i o n a p p r o x i m a t e l y t r a n s v e r s e t o t h e a x i s o f P r i n c e s s R o y a l Reach. D e p t h r e c o r d i n g s made w h i l e a t t e m p t i n g t o c o l l e c t a sample on S t a t i o n J-160 i n d i c a t e t h a t t h e s o u t h w a l l o f P r i n c e s s R o y a l Reach i s much s t e e p e r t h a n shown on t h e H y d r o g r a p h i c S e r v i c e c h a r t s . The s e d i m e n t sample c o l l e c t e d on S t a t i o n J-160 a t a d e p t h o f 285 fms.(522 m e t e r s ) c o n t a i n e d a b u n d a n t s h a l l o w and m i d - d e p t h f a u n a l FIGURE 32 LONGITUDINAL PROFILE OF PRINCESS ROYAL REACH CUMULATIVE AND FREQUENCY CURVES OF SURFICIAL SEDIMENTS FIGURE 33 TRANSVERSE PROFILE OF PRINCESS ROYAL REACH CUMULATIVE AND FREQUENCY CURVES OF SURFICIAL SEDIMENTS 105 remains. I d e n t i f i e d as c o n t r i b u t o r s t o the s h e l l d e b r i s were blu e mussels ( M y t i l u s e d u l l s ) , b r a c h i o - pods (Laqueus c a l i f o r n i c u s v a n c o u v e r e n s i s ) , p e l e - cypods ( T h y a s i r a cygnus and an u n i d e n t i f i e d p e c t i n ) , scaphopods (Cadulus t o l m e i ) and numerous s o l i t a r y c o r a l s ( B a l a n o p h y l l i a elegans and C a r y o p h y l l i a a l a s k e n s i s ) . A l s o i n c l u d e d i n the o r g a n i c d e b r i s were numerous wood fragments. One of the photo- graphs taken showed a p a r t i a l l y decomposed t r e e trunk embedded i n the sediments F i g u r e s 34 and 35 are bottom photographs taken on S t a t i o n J-160. The hummocky topography resembles t h a t appearing i n F i g u r e s 26 and 27 taken on S t a t i o n J-126. Sediment c o l l e c t e d at S t a t i o n J-162 was pre - dominantly medium t o f i n e sand, l i k e l y d e p o s i t e d as a d e l t a by the l a r g e stream f l o w i n g i n t o the i n l e t nearby (Figure 33). Sample J-161 was c o l l e c t e d f u r t h e r o f f s h o r e from J-162 at the top o f the steep slope l e a d i n g t o the b a s i n f l o o r . Sediments c o l l e c t e d from J-161 resemble those d e p o s i t e d f u r t h e r i n s h o r e (J-162) but w i t h a l e s s pronounced medium t o f i n e sand mode and a g r e a t e r abundance o f s i l t s i z e m a t e r i a l . However, the sediment c o l l e c t e d at S t a t i o n J-160 near the bottom of the sl o p e F i g u r e s 34, 35 Photographs taken i n area where abundant shallow water faunal remains were recovered. The depth t h i s s t a t i o n was 285 fathoms (522 meters).Note d i s o r d e r e d , humrnocky topo- graphy. A l l photographs approx. 1/8 X t r u e s c a l e . /0<2 a FIGURE 34 BOTTOM PHOTOGRAPHS - STA J -160 b  1 only vaguely resembles t h a t of S t a t i o n J-161„ As S t a t i o n J-162 i s l o c a t e d near the south f o o t of the s i l l , perhaps the sediment accumulating t h e r e has more than one source. The pronounced double mode i n the s i l t - c l a y r e g i o n of p a r t i c l e s i z e d i s t r i b u t i o n a l s o occurs i n the sc>diment c o l l e c t e d f u r t h e r down the i n l e t a t S t a t i o n J-145 (Figure 32). VII. C h a r a c t e r i s t i c s w i t h Depth Four g r a v i t y cores, taken a t s i t e s shown i n F i g u r e 36, were s p l i t as p r e v i o u s l y d e s c r i b e d and logged v i s u a l l y . G e n e r a l l y the cores appear f e a t u r e - l e s s . The average c o l o u r o f the t h r e e cores taken i n the upper b a s i n matches t h a t of the s u r f i c i a l s e d i - ments and was b e s t d e s c r i b e d as g r a y i s h olive(10Y4/2) The core taken from the lower b a s i n was a n o t i c e a b l y darker o l i v e gray (5Y3/2). The m a j o r i t y o f s t r u c - t u r e s shown i n F i g u r e 36 appear as s l i g h t changes i n hue which were most v i s i b l e j u s t a f t e r the core had been s p l i t and the s u r f a c e smear washed away. The average g r a i n s i z e of the core m a t e r i a l resembles t h a t of the c o r r e s p o n d i n g s u r f i c i a l sediments, i . e . the t h r e e c o l l e c t e d i n the lower p a r t o f the upper b a s i n are s i l t y c l a y s , whereas the core m a t e r i a l from the lower b a s i n i s a c l a y e y s i l t w i t h minor f i n e sand In. Cm. - -20 12- - -40 24--60 -80 38- - — - - -100 48- -120 - - - -140 I • G O - -160 _ LEGEND Q O / i i / i ' / i / / / / ' / / ? I 2\ ^ — i FIG. 36 UPPER Q Gastropod ff Scaphopod Q Pelecypod Organic fragments (wood etc) . GRAVITY CORES FROM -JERVIS INLET. ^2 Dark green gray clay Sand lens Sand grains Void (due to dessication) Minor structures 110 The core taken at Station J-123 contained three dist inct , but thin, layers of fine sand and a two- foot layer of a green-gray clay. The core taken at J-126 contained a single thin sand layer and a much thinner layer of green-gray clay. This clay repres- ented the only lithology that may be useful as a reference horizon. The sand layers appeared to represent discontinuous lenses. The competency under stress of the green-gray clay is much less than that of the more typical gray- olive to olive-gray sediment. Thus the material may be quite mobile as the sediment column compacts. This may explain the thick section in core J-123 but minor occurrence in core J-126 and absence in core J-110. Small diameter (Phleger) cores taken by Dr. E . V. G r i l l on and in the v i c in i ty of the concretion loca l i ty on Patrick S i l l contained green- gray clay starting at depths of 12 to 24 inches (30 to 60 centimeters). If large areas of the sur f i c ia l sediments on the s i l l are underlain by this clay i t would l ike ly promote decollement and slumping into the basins on either side. Wood fragments were the most abundant coarse material. These were not evenly distributed throughout I l l t h e c o r e , b u t tended t o be abundant i n p a r t i c u l a r h o r i z o n s . G e n e r a l l y the fragments o c c u r r e d w i t h t h e i r l o n g a x i s p a r a l l e l o r s u b - p a r a l l e l t o t h e b e d d i n g i n d i c a t i n g a n o n - t u r b u l e n t d e p o s i t i o n . However, i n some l a y e r s w i t h i n the c o r e s , t h e f r a g - ments were randomly o r i e n t e d i n d i c a t i n g a t u r b u l e n t d e p o s i t i o n as i n a slump (e.g. c o r e J-123 4'00" t o 4'02")„ A few s h e l l s and s h e l l fragments were v i s i b l e i n t h e c o r e s . R e c o g n i z a b l e were g a s t r o p o d , scaphopod, and p e l e c y p o d s h e l l s . The l a t t e r two b e l o n g e d t o th e same s p e c i e s r e c o v e r e d i n t h e s u r f i c i a l sediment samples ( i . e . Cadulus t o l m e i and T h y a s i r a cygnus r e s p e c t i v e l y ) . P o s s i b l y more, i n f o r m a t i o n c o u l d have been d e r i v e d from l o n g e r c o r e s . The c o l l e c t i o n o f t h e s e would p r e s e n t no problem i f the sediment m e c h a n i c a l c h a r a c t e r i s t i c s a t g r e a t e r depths do not change markedly from t h o s e o f t h e c o r e s a l r e a d y t a k e n . 112 CHAPTER 7 SEDIMENTATION IN JERVIS INLET Studie s i n the F r a s e r V a l l e y by Armstrong and Brown (1965) r e v e a l e d t h a t much o f the l a t e P l e i s t o - cene sediments are f o s s i l i f e r o u s stony, s i l t y c l a y s . The stony c l a y s are mixtures o f v a r y i n g p r o p o r t i o n s o f marine d r i f t and normal marine c l a y s . Basal sediments are marine d r i f t but these decrease i n abundance upwards and are r e p l a c e d by normal marine c l a y s . T h i s t r a n s i t i o n o c c u r r e d w i t h the waning of the c o n t i n e n t a l i c e sheet. Marine d r i f t was c a r r i e d by and d e p o s i t e d from s h e l f , berg and sea i c e . As the i c e disappeared, r i v e r s became the p r i n c i p a l method o f t r a n s p o r t . The r i v e r - b o r n e m a t e r i a l s were d e p o s i t e d as normal marine c l a y s . The totaJ. depth o f sediments w i t h i n the b a s i n s s t u d i e d was determined from s e i s m i c p r o f i l e s , but the sedimentation r a t e cannot be c a l c u l a t e d because of i t s time dependence. The average r a t e f o r the e n t i r e i n l e t o f 14 inches (35 c e n t i m e t e r s ) per 1000 years estimated by P i c k a r d (I960) f o r present s e d i - ment accumulation i s s t i l l the most v a l i d a v a i l a b l e . As P i c k a r d mentions, t h i s r a t e i s l i k e l y h i g h e r w i t h i n the upper reaches o f the i n l e t where most o f 113 t h e sediment i s added t o t h e system. M a t e r i a l added by s l u m p i n g from t h e i n l e t s i d e s would i n c r e a s e t h i s e s t i m a t e d r a t e . The g r e e n - g r a y c l a y was an anomalous l i t h o l o g y w i t h i n t h e c o r e s . The depths o f t h i s c l a y may be m i s l e a d i n g because t h e incompetent, n a t u r e o f t h e m a t e r i a l may a l l o w h o r i z o n t a l and v e r t i c a l movement as t h e t o t a l sediment column compacts. The g r e e n - g r a y c l a y was found w i t h i n t y p i c a l o l i v e - g r a y marine s e d i m e n t s . Cores t a k e n e l s e w h e r e a l o n g t h e c o n t i n e n t a l s h e l f (e.g. B a r c l a y Sound and Queen C h a r l o t t e Sound) a l s o pene- t r a t e a h o r i z o n o f g r e e n - g r a y c l a y . The s i g n i f i c a n c e o f t h i s c l a y i s not known b u t i n v i e w o f i t s appar- e n t l y w i d e s p r e a d d i s t r i b u t i o n f u r t h e r s t u d y may prove r e w a r d i n g . Sediment i s b e i n g t r a n s p o r t e d t o t h e b a s i n f l o o r s by s e v e r a l mechanisms. These i n c l u d e s e t t l i n g t h r o u g h the w a t e r column o f f i n e - g r a i n e d f l u v i a t i l e m a t e r i a l and p e r i o d i c s l u m p i n g o f c o a r s e r g r a i n e d m a t e r i a l from the s t e e p i n l e t w a l l s w i t h t h e p o s s i b l e i n i t i a t i o n o f t u r b i d i t y c u r r e n t s . The o p t i c a l t u r b i d i t y d a t a p r e s e n t e d by P i c k a r d i n d i c a t e s t h a t a major p e r c e n t a g e (up t o about 50%) o f suspendable mater- i a l added t o the i n l e t w a t e r s from t h e r i v e r a t the head i s c a r r i e d down t h e i n l e t w i t h i n t h e low s a l i n i t y s u r f a c e waters. There i s however, a marked i n c r e a s e i n t u r b i d i t y on the bottom waters o f the upper b a s i n . In e x p l a n a t i o n P i c k a r d suggested bottom c u r r e n t s or t u r b i d i t y c u r r e n t s . Slumping almost c e r t a i n l y occurs from the steep i n l e t w a l l s which have an average slope o f about 35°. The abundance of shallow water faunal remains at the base o f a steep submarine c l i f f i n the lower b a s i n ( P r i n c e s s Royal Reach) a t t e s t s to t h i s . Other a c t i v e areas are the l a r g e d e l t a i c d e p o s i t o f f Malibu Rapids, which i s swept by the t i d a l j e t through the narrows, and perhaps a l l the s m a l l e r d e l t a s which l i k e l y became unstable d u r i n g p e r i o d s of r a p i d sediment accumulation. Slumping i s a l s o thought to occur a t the i n l e t head and perhaps on the south f a c i n g f l a n k o f P a t r i c k S i l l where long unbroken slo p e s may r e s u l t i n the formation o f t u r b i d i t y c u r r e n t s . G r a v i t y cores c o l l e c t e d w i t h i n the upper b a s i n were examined only v i s u a l l y and r e v e a l e d no d i s t i n c - t i v e graded bedding. Future examination by X-ray or by t h i n - s e c t i o n may g i v e more i n f o r m a t i o n . The l a c k o f o r i e n t a t i o n of elongate o r g a n i c fragments w i t h i n c e r t a i n h o r i z o n s i n the cores suggests d e p o s i t i o n under t u r b u l e n t c o n d i t i o n s . 115 Sand lenses within the cores taken from the upper basin l ike ly represent the influence of slumping from the nearby inlet walls rather than from the inlet head. Bottom photographs taken in the upper basin show a hummocky non-oriented topography. These support Pickard's conclusion that bottom currents are probably not the cause of the turbidity pattern described. If bottom currents were suff ic iently strong to s t i r up the sediments, bed forms with a dist inct orientation should have been v i s ib le in the photographs. There is a marked difference in grain size distribution between the upper and lower basins. Patrick S i l l forms a boundary between these basins. To explain the depositional patterns, one must postu- late either that the s i l l arrests the dominant de- positional mechanism influencing the upper basin,or that the streams flowing into the lower basin have a much greater effect than those which flow into the upper basin. The r e l i e f of the s i l l is not sufficient to act as such an effective barrier i f the majority of sediment is being added to the upper basin by the sett l ing of particles through the water column. However, the s i l l is high enough that i t would l ike ly bar the passage of a density or turbidity current. 1.1 CHAPTER 8 AUTHXGENIC MINERALS I . MANGANESE CONCRETIONS 1) Source Area Manganese c o n c r e t i o n s occur i n t h e medial d e p r e s s i o n or V-notch on the s o u t h - f a c i n g slope of P a t r i c k S i l l . ( F i g ure 37 - i n p o c k e t ) . Depth o f the l o c a l i t y i s between 17 5 and 190 fathoms and the a r e a l extent i s estimated t o bo 36,000 square yards (30,000 square meters). As mentioned, the s i l l i s thought to be a bedrock f e a t u r e mantled by p o s t - P l e i s t o c e n e sediments o f v a r y i n g t h i c k n e s s . There i s l i t t l e p o s s i b i l i t y these sediments pre-date the l a s t major g l a c i a l advance i n view of the estimated t h i c k n e s s of the i c e sheet which passed over the area. The sediments c o l l e c t e d w i t h the c o n c r e t i o n s were g e n e r a l l y s i m i l a r t o those c o l l e c t e d elsewhere w i t h i n the area s t u d i e d . However, some sediment sam-. p i e s recovered from the c o n c r e t i o n l o c a l i t y i n d i c a t e d the presence o f a f l o c c u l a n t red-brown s u r f a c e l a y e r , one t o s e v e r a l c e n t i m e t e r s i n t h i c k n e s s . The s e d i - ment w i t h i n t h i s l a y e r o f t e n had a predominant coarse- g r a i n e d component which i s thought t o r e p r e s e n t a 117 lag deposit. If the abundant fine sand noted at Station J-143 came from the concretion area, then the current within the V-notch must attain ve loc i - ties of about 25 centimeters/second in order to move the sand. Underwater television observations of the loca l i ty substantiated the existence of a bottom current of approximately the velocity calcu- lated. Bottom photographs taken on the s i l l show what appears to be a lag deposit associated with the concretions. Lag deposits are not evident in photo- graphs taken near, but not on the concretion loca l i ty . Apparently, the strongest currents in the area occur where the concretions are forming. Sedimentation rates here should be correspondingly low. The total extractable iron and total carbon contents of the sediments recovered with the concretions were anomalously low. The low carbon content would reflect the sweeping away of the l ight organic material by the currsnt. Figures 38 and 39 are photographs of the concretion loca l i ty . 2) Age and Growth Rates The maximum age of the concretions would be determined by the time of ice retreat after the last major advance during the Pleistocene. This is F i g u r e s 38, 39 Photographs taken on the c o n c r e t i o n l o c a l i t y . The rounded, exposed t o par- t i a l l y b u r i e d masses are manganese c o n c r e t i o n s . Note ge n e r a l coarse t e x t u r e o f s u r f i c i a l sediments. A l l photographs approx. 1/8 X t r u e s c a l e . ue a FIGURE 38 BOTTOM PHOTOGRAPHS-CONCRETION LOCALITi  12 estimated to be about 12,000 B„P.(Armstrong et al)„ Evidence that the concretions formed i n s i t u i s provided by the recovery of s i l i c e o u s sponges having a thick manganese-iron oxide coating. The d i s c o i d shape and f r i a b l e nature of the concretions precludes transport. The maximum thickness of oxide material measured on any one concretion was 1.4 inches ( 3 5 millimeters) The accumulation rate of oxide material i s highest in the horizontal plane. Assuming the age of the concretions to be .12,000 years, the apparent growth rate would be .in the neighbourhood of 3 millimeters/ 1000 years or l e s s . This value i s somewhat lower than the general accumulation rate of 10 to 1000 millimeters/1000 years suggested by Manheim (1965) for shallow marine concretions. However, Manheim noted that concretion development i n nearshore environments may be very i r r e g u l a r with wide v a r i a - tions over small areas. The porous nature and wide v a r i a t i o n i n lamination thickness of J e r v i s Inlet concretions suggests the deposition rate was e r r a t i c , and, when deposition was occurring, much more rapid than the average rate of 3 millimeters/1000 years. 121 3) S t r u c t u r e The c o n c r e t i o n s occur i n two d i s t i n c t shapes -- d i s c o i d a l and s p h e r o i d a l . D i s c o i d a l masses are u s u a l l y l a r g e r and range up to 6 inches (15 c e n t i - meters) i n diameter. Rock fragments, mostly g r a n i t i c , form the nucleus o f a l l specimens examined. The upper s u r f a c e s o f the c o n c r e t i o n s are dark red-brown t o brown, the under s u r f a c e s l i g h t yellow-brown. Brach- iopods, s e r p u l i d worm tubes, bryozoan p l a t e s , s i l i c - eous sponges and c o r a l s may be at t a c h e d t o the upper s u r f a c e s . The d i s c o i d a l c o n c r e t i o n s f r e q u e n t l y e x h i b i t s e v e r a l i n t e r e s t i n g f e a t u r e s . A s i d e view (Figure 40a) r e v e a l s the t y p i c a l shape o f t h i s v a r i e t y w i t h a rock nucleus surrounded by a s k i r t o f oxide mater- i a l . The under-surface o f the s k i r t i s u s u a l l y even, and f l a t or concave downwards i n c o n t r a s t t o the upper s u r f a c e which i s o f t e n v e r y i r r e g u l a r . Some specimens o f d i s c o i d a l c o n c r e t i o n s have a p p a r e n t l y been r o t a t e d about a h o r i z o n t a l a x i s a t one time d u r i n g t h e i r formation. On one s i d e o f the nucleus the oxides have accumulated i n two lobes or s k i r t s to form a l i p - l i k e s t r u c t u r e w h i l e the op p o s i t e s i d e Side view o f a l a r g e d i s c o i d a l manganese c o n c r e t i o n . The nuclc i s a g r a n i t i c b o u l d e r . Major diameter 5,5 inches ( l 3 . 1 cm,) Small diameter (1,2 inches or 3 cm) s p h e r o i d a l c o n c r e t i o n w i t h a t t a c h e d s i l i c e o u s sponge. Coalescence of two discoiete-1 c o n c r e t i o n s . Major diameter approx, 3 inches (7,5 cm.) I2Z 123 of the nucleus i s n e a r l y devoid of ox i d e s . Oxide m a t e r i a l s are a p p a r e n t l y d e p o s i t e d about a nucleus i n a plane p a r a l l e l l i n g the sediment water i n t e r f a c e . The asymmetry i n p l a n view of the oxide s k i r t o f many o f the specimens i n d i c a t e s a favoured d i r e c t i o n f o r g r e a t e s t growth. T h i s o r i e n t a t i o n i s a l s o exhibited, by the oxide c r u s t s which have formed as pl a t e a u s on dead s i l i c e o u s sponges which have t o p p l e d . The n u c l e i o f s p h e r o i d a l c o n c r e t i o n s are com- p l e t e l y e n c l o s e d by o x i d e s . The d i f f e r e n c e between s p h e r o i d a l and d i s c o i d a l types may be due i n p a r t t o the s i z e and shape o f the nu c l e u s . The g e n e r a l l y s m a l l e r and more equidimensional n u c l e i o f the s p h e r o i d a l types perhaps a l l o w these t o be r o l l e d about the bottom by c u r r e n t s or animals. F i g u r e 40c shows two s p h e r o i d a l masses which have c o a l e s c e d w i t h the formation o f a surrounding s k i r t . S i n c e c o a l e s c e n s e , t h i s mass has behaved as a d i s c o i d a l c o n c r e t i o n . Cross s e c t i o n s of c o n c r e t i o n s are p i c t u r e d i n F i g u r e s 41 and 42, The dark l a m i n a t i o n s correspond t o f i n e r - g r a i n e d m a t e r i a l and are g e n e r a l l y much t h i n n e r than the l i g h t e r c o l o u r e d l a y e r s . The l i g h t e r c o l o u r e d l a m i n a t i o n s i n c l u d e most of the C r o s s - s e c t i o n o f d i s c o i d a l •manganese c o n c r e t i o n (approx. 5.5 X ) o The nucleus i s an angular fragment o f g r a n i t i c rock „ Corresponds t o area o u t l i n e d i n photograph 1 a'. T c x t u r a l , c o l o u r and t h i c k n e s s d i f f e r - ences between s u c c e s s i v e l a y e r s o f oxide m a t e r i a l s l i k e l y i n d i c a t e e r r a t i c growth r a t e s , (approx. 44 X) Corresponds t o area o u t l i n e i n photograph 1 a'. The uncon- f o r m i t y shown may have been the r e s u l t of t i l t i n g o f the c o n c r e t i o n w i t h subsequent change i n p r e f e r r e d growth d i r e c t i o n , (approx. 44 X) 12+ Cross-section of middle portion of d i s c o i d a l concretion •which had nucleus completely enclosed by oxide materials (approx. 4.3 X). Early layers of oxides were p r e f e r e n t i a l l y deposited on l e f t side of nucleus as i t appears i n the photograph. Enlargement from concretion pictured i n 'a' showing d e t r i t a l mineral included i n accreted oxide materials. D e t r i t a l minerals are gener- a l l y most abundant i n the porous,lighter coloured oxide layers (approx. 43 X). FIGURE 42 126 d e t r i t a l material,, Apparently the darker l a y e r s r e p r e s e n t p e r i o d s of slow d e p o s i t i o n . In a v e r t i c a l s e c t i o n the l a m i n a t i o n s are shown t o bo reasonably symmetrical about a h o r i z o n t a l plane. F i g u r e 41c shows the e f f e c t of e i t h e r p e r i o d s o f e r o s i o n of oxide m a t e r i a l s f o l l o w e d by renewed d e p o s i t i o n or o f changes i n p o s i t i o n o f the c o n c r e t i o n . The l a t t e r idea i s favoured because u n c o n f o r m i t i e s are not e v i d e n t . D e t r i t a l m i n e r a l s i n c l u d e d by oxides are p r e - dominantly q u a r t z and f e l d s p a r s . These a l s o dominate i n the u n d e r l y i n g sediments. 4) Chemical Composition The chemical composition of the c o n c r e t i o n s was determined by Dr. E. V. G r i l l o f the I n s t i t u t e o f Oceanography (Table 6 ) . For purposes o f comparison, Table 7 g i v e s the average compositions o f deep ocean and B a l t i c Sea c o n c r e t i o n s and the composition of shallow water c o n c r e t i o n s from the V e r m i l i o n Sea o f f Baja C a l i f o r n i a (Manheim 1965 and Mero 1965). T o t a l carbon analyses of J e r v i s I n l e t c o ncre- t i o n s i n d i c a t e d a carbon content equal to or s l i g h t l y l e s s than t h a t of the u n d e r l y i n g sediments (which had an average content of 1.26 per c e n t ) . 127 Table 6 Chemical Analyses o f J e r v i s I n l e t C o n c r e t i o n s (Analyses by Dr. E. V. G r i l l , I.O.U.3.C.) Sample A* B % S o l u b l e 81. 75 81. 0 9 F r a c t i o n S o l u b l e I n s o l u b l e S o l u b l e I n s o l u b l e F e 2 0 3 7.65 3.06 6.55 2.45 FeO - 1.79 .„ 1.23 MnO 51.70 0.10 52.31 0.10 S i 0 2 2.3 64.9 67.1 AI2O3 0.41 15.8 0.71 15.3 Ti02 0.096 0.62 0.035 0.58 P2O5 0.94 0.11 0.72 0.16 Ka20 1.06 2.27 1.05 2.37 K 20 1.11 1. 52 1.18 1.51 MgO 3.19 2.24 3.36 1.66 CaO 1.55 3.19 1.56 3.17 BaO 0.27 0. 55 0.36 0.83 M0O3 0.041 0.007 0.049 0.006 V2O5 0.028 - 0.043 -CoO 0.020 - 0.022 -NiO 0.040 - 0.060 -CuO 0.0084 - 0.014 -ZnO 0.0029 - 0.0056 -PbO ND - ND -Te02 0.018 - 0.020 -S 0 3 0.13 - ... -C02 0.56 - -NaCl 1.09 - 1 . 0 9 -A c t i v e 0 10.12 — 10.09 --110 H 20 3.8.1 0.93 8.84 0.94 H 0+110 8.63 2.94 8.29 3.17 Sum 99.82 100.03 96.41 100.58 A l l a n a l y s es are presented as weight percentages on an a i r d r i e d b a s i s . A dash i n d i c a t e s no a n a l y s i s and ND means not d e t e c t e d . *Sample A (the u n f r a c t i o n a t e d c r u s t ) a l s o c o n t a i n s 0.0012% Cr 203,, Table 7 Comparison o f Elemental Analyses o f Manganese Concretions J e r v i s I n l e t B a l t i c Sea Average Deep Ocean V.S.78 A B (i©st .average)' A l 1.70 1.83 1.54 8.57 1.90 Ca 1.33 1.33 1.21 1.57 1.16 Co .013 .014 .016 0.28 ..010 Cu .0055 . 0091 . 0048 0.40 .010 Fe 5.01 4.21 22.4 11.7 .86 K .98 1.03 .076 .68 .96 Mg 1.82 1.83 .57 1.38 -Mn 32.72 32.82 14.0 19.0 38.9 No .023 .027 . 013 .038 .022 Na .95 .97 .35 2.08 -N i .026 .038 .075 .58 .045 p .34 .27 .70 .19 -Pb ND ND . 0038 .10 .025 T i .096 . 089 . 11 .47 .. 07 Te .012 . 013 - - -Zn .0019 .0036 .008 0.04-0.40 .023 J e r v i s I n l e t A D i s c o i d a l type - G r i l l 1968 B SpheroidaJ l. type B a l t i c Sea Average - Manheim 1965 Deep Ocean (estimated average) Manheim 1965 V.S. 78 ( V e r m i l i a n Sea) - Mero 1965 129 Hov;ever, the carbon analyses re p r e s e n t an avercige. over the depth of p e n e t r a t i o n o f the sampler (about 12 inches) and t h e r e f o r e are only an i n d i c a t i o n . The r a t i o o f manganese t o i r o n (Mn/ F o) has been c o r r e l a t e d w i t h depth and used i n an attempt t o d i s t i n g u i s h and c l a s s i f y c o n c r e t i o n l o c a l i t i e s (Mero, 1965). These r a t i o s can be extremely v a r i a b l e w i t h a c o n s i d e r a b l e range sometimes o c c u r r i n g w i t h i n a s i n g l e specimen. In g e n e r a l , c o n c r e t i o n s from n e r i t i c and l a k e environments have a Mn/p G r a t i o o f l e s s than u n i t y . A m a j o r i t y o f p e l a g i c nodules have a r a t i o o f g r e a t e r than u n i t y . J e r v i s I n l e t c o n cre- t i o n s have an average Mn/ F e r a t i o of 5, the r e b e i n g l i t t l e v a r i a t i o n between samples. While t h i s r a t i o does not f o l l o w the norm f o r shallow water concre- t i o n s , i t i s by no means unique. Some nodules c l o s e t o the North and South American c o a s t s and near Japan have Mn/ F e r a t i o s ranging from 12 t o 50 ( P r i c e , 1965). As more analyses are p u b l i s h e d , the l e s s e v i d e n t becomes the supposed r e l a t i o n s h i p between depth and Mn/ F r a t i o . The oxidation state of the manganese was c a l - culated by G r i l l ( G r i l l , Murray and Macdonald,1968) to be MnO]_o87 for sample A and MnO^ Q 6 for sample B, assuming a l l the active oxygen was associated with higher oxides of manganese. This O/Mn r a t i o i s somewhat higher than the average value for n e r i t i c areas (1.55) and lower than that for the pelagic areas (1.9 - 2.0) (Manheim, 1965). Unlike the Mn O /p e r a t i o , the r a t i o apparently has a s i g - n i f i c a n t covariance with depth (Manheim 1965). However, a considerable overlap of ^/jy[n r a t i o s exists between shallow and deep-water concretions. The minor element content of J e r v i s Inlet concretions approximates that of other n e r i t i c occurrences. Elements of economic concern such as Ni, Cu, Zn, and Co have abundances ranging from 1 to 2 orders of magnitude below the estimated deep ocean average. Lead was not detected while molybdenum occurred with an abundance s i m i l a r to that of deep sea concretions. The o r i g i n a l analyses by G r i l l (Table 6) were given as oxide percentages of the soluble and insoluble (in a heated solution containing 10 ml of hydrochloric acid and 10 g. of hydroxylamine hydrochloride) f r a c t i o n s . The major 13.1 elements i n the i n s o l u b l e f r a c t i o n were s i l i c o n , aluminum, i r o n , calcium, magnesium and sodium. These l i k e l y formed the d e t r i t a l s i l i c a t e m i n e r a l s which were i n c l u d e d w i t h i n the ferromanganese oxide c r u s t s . The phosphorus content of manganese c o n c r e t i o n s i s thought to be r e l a t e d t o t h e i r a s s o c i a t i o n w i t h s t a g - nant or semi-stagnant sediments (Manheim 1965). J e r v i s I n l e t c o n c r e t i o n s , which are a s s o c i a t e d w i t h semi-stagnant sediments, c o n t a i n e d approximately 0.3 per cent phosphorus which i s c o n s i d e r e d common f o r shallow marine forms. T e l l u r i u m was d e t e c t e d i n the s o l u b l e f r a c t i o n s o f both the J e r v i s I n l e t samples analyzed. 5) Mineralogy T o d o r o k i t e was i d e n t i f i e d as the p r i n c i p a l manganese m i n e r a l i n J e r v i s I n l e t c o n c r e t i o n s ( G r i l l , Murray and Macdonald 1968). The suggested composition ( S t r a c z e k , Horen, Ross and Warshaw, 1960) i s : (Ca,Na,Mn + 2,K) (Mn + 4,Mn + 2,Mg) 6 0 1 2 .3H 20 C a l c u l a t i o n o f atomic p r o p o r t i o n s (the number o f atoms per u n i t c e l l ) of Mn + 4, Mn + 2, Mg ( i n c l u d i n g Co, Cu), Ca ( i n c l u d i n g Ba, S r ) , Na and K f o r s o l u b l e J e r v i s I n l e t m a t e r i a l agrees w i t h s i m i l a r data p r e s - ented f o r t o d o r o k i t e by other a u t h o r s . ( G r i l l et a l 1968). 132 6) Formation o f C o n c r e t i o n s The mechanism of formation of manganese concre- t i o n s can o n l y be p o s t u l a t e d . Many workers (e.g. Manheim, 1965 and P r i c e , 1967) c o n s i d e r the growth o f c o n c r e t i o n s to be due to the p r e c i p i t a t i o n o f elements from the i n t e r s t i t i a l waters o f the u n d e r l y i n g s e d i - ments. Metals present i n low c o n c e n t r a t i o n s i n sea water are d e p o s i t e d as oxides or as ions adsorbed on c l a y and o r g a n i c p a r t i c l e s . Release o f these metals to the i n t e r s t i t i a l waters would occur w i t h s e d i - ment b u r i a l due t o the r e d u c i n g e f f e c t of the o r g a n i c matter. The r e s u l t i n g h i g h c o n c e n t r a t i o n of elements i n the i n t e r s t i t i a l waters as w e l l as e l e c t r o c h e m i c a l d i f f e r e n c e s between the adjacent r e d u c i n g and o x i d i z - i n g environments w i l l set up a d i f f u s i o n p o t e n t i a l so c a u s i n g the upward movement o f these elements ( P r i c e , 1967). T h i s mechanism c o u l d produce a v a r i e t y o f con- c r e t i o n h a b i t s . Manheim (1961) suggests t h a t i n areas where the sediment water i n t e r f a c e i s n e u t r a l or reducing, nodules w i l l not form but the t r a c e - element content o f the bottom waters w i l l be i n c r e a s e d . Conversely, i n areas where the s u r f i c i a l sediments are h i g h l y o x i d i z e d , pea ores may form w i t h i n the sediment .133 i t s e l f (Gripenburg, 1934). The most common h a b i t i s the d i s c o i d c o n c r e t i o n ( K i n d l e , 1932.,Gripenburg, 1934, Manheim,1965). Although the b a s i c mechanisms f o r the formation of c o n c r e t i o n s i n the shallow water and open ocean environment are b e l i e v e d s i m i l a r , the c o n c e n t r a t i o n o f many minor metals such as Cu, Co, N i , Pb, and Zn tends t o be one to s e v e r a l orders o f magnitude l e s s i n shallow than i n the deep ocean v a r i e t i e s . T h i s t r e n d i s thought t o be due t o d i f f e r i n g c o n c e n t r a - t i o n s and types o f org a n i c matter present i n the two environments. In n e r i t i c and l a c u s t r i n e c o n d i t i o n s , b u r i a l o f the sediment and r e d u c t i o n i n the presence of o r g a n i c m a t e r i a l r e l e a s e s most Mn, Pb, and Zn to the i n t e r s t i t i a l waters w h i l e the l o s s o f Fe, N i , Co and Cu i s s m a l l e r and p o s s i b l y due t o r e t e n t i o n o f these elements i n .iron s u l p h i d e s ( P r i c e , 1967). Water s o l u b l e o r g a n i c s , amino a c i d s and humic a c i d s w i t h i n the sediments are a l s o thought t o a f f e c t metal c o n c e n t r a t i o n s o f shallow water c o n c r e t i o n s by modifying the i n o r g a n i c uptake o f minor metals such t h a t Pb, Zn, and Cu are not sorbed by the manganese-iron phases. In the open ocean e n v i r o n - ment the low abundance o f or g a n i c matter i n the .134 sediments would l i k e l y minimize the m o b i l i t y and upward d i f f u s i o n of manganese and other elements d u r i n g sediment burial„ 7) Abundance and Value F i g u r e 43a shows manganese-iron c o n c r e t i o n s as they were recovered i n a grab sampler. The bulk of the sample i s coarse t o f i n e - g r a i n e d sediment on which the c o n c r e t i o n s form. F i g u r e 43b i s an approximate average sample recovered from one lower- i n g o f the grab on to the l o c a l i t y . The square out- l i n e w i t h i n which the c o n c r e t i o n s are p i c t u r e d r e p r e s e n t s the area covered by the open jaws of the sampler. The t o t a l a i r d r i e d weight of the c o n c r e t i o n s p i c t u r e d was 1.97 pound (.894 kilograms) of which 72.9 per cent or 1.43 pounds (.684 kilograms) was oxide m a t e r i a l . Since the area w i t h i n the open jaws i s approximately 0.2 square yards (.17 square meters) the c o n c e n t r a t i o n of oxide m a t e r i a l , assuming t o t a l r ecovery, vjould be 7.1 pounds/square y a r d (3.9 k i l o - grams/square meter). I f the area of the d e p o s i t i s taken to be 36,000 square yards (30,000 square meters) the tonnage of oxides present would be 128 s h o r t tons (117 m e t r i c t o n s ) . T h i s estimate c o u l d P e t t e r s s e n grab sampler on deck wit h recovered manganese concre- t i o n s and sediment s u b s t r a t e . An average d e n s i t y of manganese c o n c r e t i o n s . Black o u t l i n e r e p r e s e n t s area covered by open jaws o f P e t t e r s s e n grab sampler. The area i s 1/5 meter ,, Top view o f l a r g e d i s c o i d a l c o n c r e t i o n . Note the p r e f e r r e d d i r e c t i o n f o r a c c r e t i o n o f oxid e s . (Major diameter i s 5.5 i n . or 13.1 cm.) a c FIGURE 43 136 be i n e r r o r by a c o n s i d e r a b l e amount (perhaps + 50 per cent) as the area of the l o c a l i t y i s p o o r l y known and only one sample which, from photographs,appeared t o r e p r e s e n t an average sample, was weighed. While the above method o f determining r e s e r v e s o f a u t h i g e n i c oxides on P a t r i c k S i l l i s ac c u r a t e w i t h i n i t s e l f , many s i m i l a r samples w i l l have t o be taken i n order to estimate reasonably a c c u r a t e l y the t o t a l tonnage. Perhaps a b e t t e r method t o determine t h i s i n f o r m a t i o n would be t o combine a small underwater camera and l i g h t source with the grab sampler. I f the camera was t r i g g e r e d 10 f e e t or so o f f the bottom the c o n c e n t r a t i o n o f c o n c r e t i o n s w i t h i n the grab sampler c o u l d be e x t r a p o l a t e d to the much l a r g e r area covered by the photograph. Underwater t e l e v i s i o n was t r i e d as a method t o determine c o n c e n t r a t i o n s but c o n c r e t i o n s c o u l d not be d i s t i n g u i s h e d from b a r r e n b o u l d e r s w i t h the system a v a i l a b l e . I I . Iron C r u s t s M a i n t a i n i n g s t a t i o n over the c o n c r e t i o n l o c a l i t y was d i f f i c u l t and only about 50 per cent o f the attempts t o o b t a i n samples were s u c c e s s f u l . One attempt, which proved t o be too f a r t o the west by about 100 t o 200 f e e t r e s u l t e d i n the sampler h i t t i n g 137 e i t h e r bedrock or very l a r g e b o u l d e r s . However, w i t h i n the grab sampler were f e r r u g i n o u s c r u s t s ( F i g u r e 44) which had been broken o f f the rock s u r f a c e . The e x t e r n a l s u r f a c e s of the c r u s t s vary from smooth t o i r r e g u l a r . Cross s e c t i o n s r e v e a l a d i s - t i n c t l a y e r i n g . The s u r f a c e or outer l a y e r i s r i n d - l i k e and v a r i e s i n t h i c k n e s s from about .04 to 0.6 i n . (.1 t o 15 mm). The c o l o u r i s red brown t o dark brown and b l a c k . The m a t e r i a l i s non- porous and has a v i t r e o u s t o o p a l i n e l u s t r e as i f d e p o s i t e d as a g e l . On d e s s i c a t i o n a t room tempera- t u r e the t h i c k e r p o r t i o n s have cr a c k e d forming i n t e r - l o c k i n g p o l y h e d r a l masses. D e p o s i t i o n o f the g e l - l i k e m a t e r i a l must have oc c u r r e d reasonably r a p i d l y as l a r g e b u b b l e - l i k e c a v i t i e s were formed (Fi g u r e s 44b, c ) . The p r i n c i p a l m i n e r a l forming t h i s outer l a y e r i s g o e t h i t e (FeOOH). The bulk of the m a t e r i a l forming the c r u s t i s r e d d i s h y e l l o w to yellow-brown, f i n e - g r a i n e d , l o o s e and very porous. An X-ray powder d i f f r a c t i o n p a t t e r n i n d i c a t e d the p r i n c i p a l minerals t o be q u a r t z , f e l d s p a r and g o e t h i t e . T h i s m a t e r i a l l i k e l y F i g u r e 44 a Iron c r u s t as recovered from rock face near but not on ( i . e . w i t h i n about 100 meters) the c o n c r e t i o n l o c a l i t y , (approx. 1.6 X) b,c B u b b l e - l i k e s t r u c t u r e shown by some of the i r o n c r u s t s r e covered from v i c i n i t y o f c o n c r e t i o n l o c a l i t y . Note l a y e r i n g w i t h i n m a t e r i a l of bubble and base and fragments o f sponges w i t h i n bubble. Approx. 1.6 X /38 139 r e p r e s e n t s sediments which accumulated and were then i n c l u d e d i n the s t r u c t u r e o f the c r u s t s by the deposi.tion of the g e l - l i k e m a t e r i a l . The l a y e r i n g mentioned i s due t o a l t e r n a t i n g l a y e r s of l o o s e porous and v i t r e o u s materials,. The nature of the m a t e r i a l which formed the bond wi t h the rock s u r f a c e i s not known. There i s no f e a t u r e o f the c r u s t which would g i v e an i n d i c a t i o n of age. I I I . " G l a u c o n i t e - M o n t m o r i l l o n o i d " P e l l e t s Murray and Macintosh (1968) d e s c r i b e d i n t e r s t r a t i - f i e d g l a u c o n i t e - m o n t m o r i l l o n o i d p e l l e t s from Queen C h a r l o t t e Sound. M i n e r a l o g i c and morphologic s t u d i e s o f J e r v i s I n l e t sediments r e v e a l e d the presence of p h y s i c a l l y i d e n t i c a l p e l l e t s (Figure 18d) . p e l l e t s were found over a c o n s i d e r a b l e area o f the s i l l as w e l l as i n l o c a l i z e d areas on the s i d e s o f the lower b a s i n . P e l l e t s were not noted i n samples c o l l e c t e d from the upper b a s i n . No X-ray or chemical analyses have been made of these p e l l e t s to date. The p e l l e t s are g e n e r a l l y s p h e r o i d a l and l i g h t y e l l ow-green t o gray-green i n c o l o u r . In the f r a c - t i o n s examined, the p e l l e t s are most abundant i n the f i n e sands ( i . e . 88 t o 63/u or 3.5 t o 4 0 ) but some .140 samples c o n t a i n e d p e l l e t s i n the 500 t o 350/u (1.0 t o 1.5 0 ) range. Both these f r a c t i o n s o f sample J-135, which i s near but not on the c o n c r e t i o n l o c a l i t y , were estimated to be 40% p e l l e t s . The f i n e r f r a c t i o n o f sample J-164 was a l s o about 40% p e l l e t s . Sediments c o l l e c t e d with c o n c r e t i o n s were, about 15% p e l l e t s f o r the f r a c t i o n s examined . Often recovered w i t h the p e l l e t s were sponge s p i c u l e s and r a d i o l a r i a n t e s t s . IV DISCUSSION The s i l l environment, e s p e c i a l l y on and near the medial d e p r e s s i o n i s m i n e r a l o g i c a l l y unique w i t h i n the study a r e a . Why manganese c o n c r e t i o n s and i r o n c r u s t s should form there and a p p a r e n t l y not elsewhere w i t h i n upper J e r v i s I n l e t i s not known. The area o f the medial d e p r e s s i o n i s a f f e c t e d by a bottom c u r r e n t w i t h an approximate v e l o c i t y o f 25 centimeters/second. T h i s c u r r e n t l i m i t s the d e p o s i t i o n of d e t r i t u s , both minerogenic and o r g a n i c , and i n some areas i s capable of winnowing, w i t h subsequent formation o f l a g depos- i t s . The s u r f i c i a l sediments of the c o n c r e t i o n l o c a l i t y are a dark red-brown c o l o u r f o r a depth o f about 1 to 2 c e n t i m e t e r s . Below t h i s l a y e r the s e d i - ments are g e n e r a l l y a t y p i c a l o l i v e - g r e e n . The 141 c o l o u r o f the s u r f i c i a l sediments i n d i c a t e s o x i d i z i n g c o n d i t i o n s probably due t o the constant renewal o f o v e r l y i n g waters and the lower o r g a n i c matter content o f the sediments. I r o n i s b e i n g d e p o s i t e d as g o e t h i t e c r u s t s on exposed rock s u r f a c e s w i t h i n the medial d e p r e s s i o n of the s i l l . A p p a rently s i m u l t a n e o u s l y and i n c l o s e p r o x i m i t y , manganese c o n c r e t i o n s are forming around rock fragments r e s t i n g on sediments. Whereas the source o f the g o e t h i t e i s l i k e l y a g e l formed i n the seawater, the c o n c r e t i o n - f o r m i n g manganese i s appar- e n t l y d e r i v e d from the s u b s t r a t e . F u r t h e r s t u d i e s which might prove i n t e r e s t i n g would be d e t e r m i n a t i o n of the c o n c e n t r a t i o n o f i r o n on the s u r f a c e versus the underside o f c o n c r e t i o n s and, although p o s s i b l y not y e t f e a s i b l e , the d e t e r m i n a t i o n o f groundwater c i r - c u l a t i o n w i t h i n the s i l l . What are thought t o be " g l a u c o n i t e - m o n t m o r i l l o n o i d " p e l l e t s are a l s o forming w i t h i n upper J e r v i s I n l e t , but they are not unique t o the s i l l . C e r t a i n samples c o l l e c t e d from the w a l l o f the lower b a s i n c o n t a i n e d these p e l l e t s i n c o n s i d e r a b l e q u a n t i t y , but no p e l l e t s were found i n the sediments o f the upper b a s i n . 142 Whether these p e l l e t s form on or beneath the sediment- water i n t e r f a c e i s not known. The depth z o n a t i o n n o t i c e d by Porrenga (1966) i n which g o e t h i t e occupies the 0 t o 50 meter zone and g l a u c o n i t e the 30 t o 2000 meter zone i s o n l y p a r t l y a p p l i c a b l e i n t h i s area. However, s i n c e i t i s not known i f the g o e t h i t e c r u s t s and p e l l e t s are forming p r e s e n t l y or what the f l u c - t u a t i o n s i n sea l e v e l have been s i n c e P l e i s t o c e n e time, l i t t l e can be s a i d . More thorough sampling might n e c e s s i t a t e r e v i s i o n of ideas about d i s t r i b u t i o n p a t t e r n s . V EXPLORATION I f , a t some time i n the f u t u r e , the mining o f con- c e n t r a t i o n s o f shallow marine c o n c r e t i o n s becomes p r o f i t a b l e , the q u e s t i o n w i l l a r i s e as t o how t o l o c a t e these d e p o s i t s . At present, the b e s t guide would probably be bathymetry. Favourable c o n d i t i o n s appear t o be achieved on the c r e s t s o f banks and s i l l s or on b a s i n margins. A l l p r e s e n t l y known l o c a l o c c u r r - ences o f c o n c r e t i o n s have been found i n the 100 t o 200 fathom range. However, the s i g n i f i c a n c e of depth i s not known. Movement o f the o v e r l y i n g waters i s needed t o m a i n t a i n a low sediment accumulation r a t e and o x i d i z i n g c o n d i t i o n s w i t h i n the bottom waters and top c e n t i m e t e r or so o f the sediments. The occurrence 143 of a stagnant to semi-stagnent b a s i n adjacent t o the e l e v a t e d area i s thought to be important ( P r i c e 1967). To date, not enough i s known about t r a c e element c o n c e n t r a t i o n s w i t h i n sea water and sediment i n areas where c o n c r e t i o n s form to enable one t o use such data f o r e x p l o r a t i o n . 144 3 i b l i o g r a p h y Armstrong, J . E. and W„ L. Brown, .1954, Late Wisconsin Marine D r i f t and Associated Sediments of the Lower Fraser Valley, B r i t i s h Columbia, Canada. B u l l . Geol. Soc. Amer., Vol. 65: 349-364 Armstrong, J . E . et al., 1965, Late Pleistocene Stratigraphy and Chronology i n Southwestern B r i t i s h Columbia and Northwestern Washington. B u l l . Geol. Soc. Amer., Vol.76: 321-330 Bacon, W. R. , .1.957, Geology of Lower Je r v i s Inlet, B. C. Dept.of Mines and Petroleum Resources B u l l e t i n 39 3 . C. Natural Resources Conference, 1956, B r i t i s h Columbia Atlas of Resources Carter, N. M. 1934 Physiography and Oceanography of Some B r i t i s h Columbia Fjords, Proc. F i f t h P a c i f i c S c i . Cong. 1933, Vol.1: 721-733 Cockbain, A. E. 1963, D i s t r i b u t i o n of Sediments on the Continental Shelf o f f the Southern B. C. Coast, Manuscript Report 15, I.O.U.B.C. Dobrin, M.B., 1960, Introduction to Geophysical Prospecting McGraw-Hill, 446 pp. Folk, R. L. 1961, Petrology of Sedimentary Rocks, The University of Texas, 154 pp. Folk, R. L. 1966, A. Review of Grain Size Parameters, Sedimentology 6: 7 3-93 Folk, R. L. and W.C. Ward, 1957, Brazos River Bar, a Study i n the Significance of Grain Size Parameters, J . Sediment. Petrol., 27: 3-27 G r i l l , E.V., J . W. Murray and R. D. Macdonald 1968, Todorokite i n Manganese Nodules from a B r i t i s h Columbia Fjord, Nature, Vol.129,No.552: 358-359 Grim, R. E„, 1968 Clay Mineralogy, McGraw-Hill,596 pp. Gucleur, S.M. and M.G. Gross,1964, Recent Marine Sedi- ments i n Saanich Inlet, a Stagnant Marine Basin, Limn.and Ocean., Vol.9, No.3: 359-37 5 H o l l a n d , S„S., 1964, Landforms o f B r i t i s h Columbia, Bo C. Dept.of Mines and Petroleum Resources, B u l l . No.48 K i t t r i c k , J.A. and S„W. Hope, 1963, a Procedure f o r the P a r t i c l e S i z e S e p a r a t i o n o f S o i l s f o r X-ray D i f f r a c t i o n A n a l y s i s , S o i l S cience 95s 319-325 L a z i e r , J.R.N., 1963, Some Aspects o f the Oceanographj. S t r u c t u r e i n the J e r v i s I n l e t System, M.Sc T h e s i U n i v e r s i t y of B r i t i s h Columbia LeRoy, O.E., 1908, P r e l i m i n a r y Report on a P o r t i o n o f the Main Coast o f B r i t i s h Columbia and Adjacent I s l a n d s , G eologic Survey o f Canada, Report No.996 P u b l i c a t i o n s 1908 V o l . 1 Manheim, F. T., 1965, Manganese-Iron Accumulations i n the Shallow Marine Environment, Symposium on Marine Geochemistry, Narragansett Marine Labor- ator y , U n i v e r s i t y of Rhode I s l a n d , Occas. P u b l i c . No. 3 - 1965. 217-275 Mero, J . L. 1965, The M i n e r a l Resources o f the Sea, E l s e v i e r P u b l i s h i n g Company, 312 pp. Murray, J.W. and E.E.Mackintosh, 1968, Occurrence o f I n t e r s t r a t i f i e d G l a u c o n i t e - M o n t m o r i l l o n o i d P e l l e t s , Queen C h a r l o t t e Sound, B r i t i s h Columbia, Canadian Jour, o f E a r t h S c i e n c e s , 5s 243-247 Pa n t i n , H.M. 1969, The Appearance and O r i g i n o f Colours i n Muddy Marine Sediments Around New Zealand, New Zealand J o u r . o f Geol. and Geoph., V o l . 12, No.Is 51-56 Peacock, M. A. 1935, Fjord-Land o f B r i t i s h Columbia, B u l l . Geol. Soc.of Amer.46s 633 P i c k a r d , G. L.,1961, Oceanographic Features o f I n l e t s i n the B r i t i s h Columbia Mainland Coast, J o u r . F i s h e r i e s Research Board o f Canada, V o l . 18, No. 6: 907-999 P i c k a r d , G.L. and G.K.Rodgers, 1959, Current Measure- ments i n Knight I n l e t , B r i t i s h Columbia, Jour, o f F i s h e r i e s Research Board o f Canada, 16: 635-678 P i c k a r d , G.L. and L.F. Giovando, 1960, Some Observa- t i o n s o f T u r b i d i t y i n B r i t i s h Columbia I n l e t s , Limn, and Oceanog. 5 (12): 162-170 Porrenga, D.H., 1966, G l a u c o n i t e and Chamosite as Depth I n d i c a t o r s i n the Marine Environment. Marine Geology 5: 495-501 Postma, H., 1967, Sediment Transport and Sedimenta- t i o n i n the E s t u a r i n e Environment i n E s t u a r i e s , Amer. Assoc. Adv. o f Sc i e n c e Publ. No. 83 :158-180 P r i c e , N.B., 1967, Some Geochemical Observations on Manganese-Iron Oxide Nodules from D i f f e r e n t Depth Environments, Marine Geology 5; 511-538 Roddick, J.A, 1965, Vancouver North, Coquitlam and P i t t Lake Map J.reas, B r i t i s h Columbia, G.S.C. Memoir 335 : 376 pp Shepard, P.P., 1954, Nomenclature Based on S a n d - S i l t - C lay R a t i o s , Jour. Sedimentary P e t r o l o g y , V o l . 24: 151-158 Soren, R.K. 1967, Manganese Nodules: Nature and S i g - n i f i c a n c e o f I n t e r n a l S t r u c t u r e , Economic Geology, V o l . 62, N o . l : T i f f i n , D.L. and J.W. Murray, 1966, Mapping O f f s h o r e w i t h Continuous Seismic, O i l Week, Nov.7,1966 Toombs, R.B.,1956, Bute I n l e t Sediments, Trans.Roy. Soc. Canada, Ser. 111,50: 59-65 Trask, P.D., 1938, Organic Content o f Recent Marine Sediments, Recent Marine Sediment -- A Symposium, Dover P u b l i c a t i o n s , 7 36 pp. T r i t e s , R.W„,1965, A Study o f the Oceanographic S t r u c t u r e i n B r i t i s h Columbia I n l e t s and Some of the Determining F a c t o r s , PhD T h e s i s , U n i v e r - s i t y o f B r i t i s h Columbia, Vancouver, B.C. Weaver, C.E.,1958, Geologic I n t e r p r e t a t i o n o f A r g i l l a ceous Sediments, P a r t 1, O r i g i n and S i g n i f i c a n c e o f C lay M i n e r a l s i n Sedimentary Rocks, Bull.Amer Assoc. Pet. Geol.,Vol.42, No.2 : 254-271 JERVIS INLET (Northern Portion) FIGURE 3 SAMPLE LOCATIONS 123° 46 1 L E G E N D GRAB SAMPLE SEISMIC PROFILE 123 s 42 CAMERA  JERVIS INLET (Northern Portion) FIGURE 14 TOTAL CARBON PERCENT 123 58 123,54 •1.87 123° 50' 123° 46 123* 42 ' i \ ! I i!_L JERVIS INLET (Northern Portion) FIGURE 20 SEDIMENT-TYPE DISTRIBUTION 123 58 123° 54 123° 50' 123° 46 123° 42 50*07'00 50° 06 0d 50* 05 00 JERVIS INLET (Northern Portion) FIGURE 21 CLAY PARTICLE PERCENT 123 46 123* 42

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