Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The impact of human activity on deltaic sedimentation, marshes of the Fraser River Delta, British Columbia Hales, Wendy J. 2000

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-ubc_2000-486419.pdf [ 19.82MB ]
Metadata
JSON: 831-1.0089776.json
JSON-LD: 831-1.0089776-ld.json
RDF/XML (Pretty): 831-1.0089776-rdf.xml
RDF/JSON: 831-1.0089776-rdf.json
Turtle: 831-1.0089776-turtle.txt
N-Triples: 831-1.0089776-rdf-ntriples.txt
Original Record: 831-1.0089776-source.json
Full Text
831-1.0089776-fulltext.txt
Citation
831-1.0089776.ris

Full Text

The Impact of Human Activity on Deltaic Sedimentation, Marshes of the Fraser River Delta, British Columbia By Wendy J. Hales B.A. University of British Columbia, 1989 M.Sc. McMaster University 1992 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Department of Geography) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA April 2000 © Wendy J. Hales In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of & , r > a / The University of British Columbia Vancouver, Canada Date DE-6 (2/88) Abstract To determine the impact of human activity on marsh sedimentation rates and growth patterns, the recent history of marsh development at the mouth of the Fraser River delta has been constructed. Lateral marsh growth is assessed through aerial photographs, while vertical sedimentation rates are resolved using sediment cores. Changes in marsh sedimentation rates and patterns were compared with historical information about natural events and human activity in the study area, to show that marsh sedimentary sequences record the impact of human activity. A total of 35 cores were collected, of which the seven longest (3.03 to 2.75 m in ground penetration length) with the best lamination sequences were analysed for 1 3 7Cs, heavy metal concentration, organic content, and sediment density and texture. The combination of these analyses enabled the cores to be dated to 1894, prior to large scale human interference in the deltaic system. To enable correlation between the cores, they were analysed for environmental magnetism. Aerial photographic mosaics were created for the years 1930, 1954, 1974 and 1994 in order to determine the rate of lateral marsh growth. Historical maps were also examined, but due to irresolvable map error, it was not possible to determine marsh areas accurately prior to the advent of aerial photography. The sedimentary record indicates that the marshes experienced rapid aggradation, an average of 2.10 g/cm /a, between 1910 and 1954, the period during which major river training structures were constructed in the study area. Laterally, the marshes also grew rapidly during this period: between 1930 and 1954 they experienced a 16 % increase in area (93 x 103 m2/a), including losses due to land reclamation. After this period, marsh aggradation slowed, as did lateral growth in most areas. The decline in vertical growth is attributed to the marshes attaining a balance with the new environmental conditions created by river management. This research shows that sedimentary sequences from undisturbed estuarine marshes provide historical information about the impact of human activity on sedimentation rates and patterns. In addition, earlier portions of the marsh sequences can be used to establish information about natural environmental conditions for comparison purposes in areas where such background data are otherwise unavailable. ii Table of Contents Abstract ii Table of Contents . iii List of Tables vi List of Figures vii Acknowledgements , viii C H A P T E R 1: I N T R O D U C T I O N 1 1.1 Introduction 1 1.2 Objectives 2 1.3 Marsh Dynamics 3 1.3.1 Marsh Development 4 1.3.2 Sedimentation and Erosion 5 1.4 Changing Relative Sea Level 7 1.5 Marshes and Human Activity 8 C H A P T E R 2: F R A S E R R I V E R D E L T A 11 2.1 Introduction 11 2.2 Natural History and Processes 13 2.2.1 Development and Structure of the Delta 14 2.2.2 Deltaic Processes 16 2.2.3 Sedimentation and Changes in the Intertidal and Subtidal Areas 21 2.2.4 Impact of Human Activity 23 2.3 Human History 25 2.3.1 Native Population 25 2.3.2 European Discovery and Settlement 25 2.3.3 Industrial Development: Pollution 26 2.4 Physical Alteration of the Delta 27 2.4.1 Dyking 28 2.4.2 Snag Removal 29 2.4.3 Dredging 29 2.4.4 River Migration and Training 31 2.4.4.1 River Mouth 32 2.4.4.2 Steveston and Ladner Bend 35 2.4.4.3 Trifurcation and New Westminster 37 2.4.5 River Management Time Periods 38 C H A P T E R 3: M A P P I N G T H E D E L T A 40 3.1 Introduction 40 3.2 Hydrographic Charts 41 3.2.1 History of Mapping the Fraser River Delta .41 3.2.2 Reliability and Accuracy of Fraser River Charts 43 3.3 Mapping Historical Marshes of the Fraser River delta 46 3.3.1 British Admiralty and Canadian Hydrographic Charts 46 3.3.2 Public Works Canada Charts 47 3.3.3 Aerial Photographs 49 iii 3.4 Results.... 51 3.4.1 Changes to Channel Morphology 51 3.4.2 Marsh Development 52 CHAPTER 4: SEDIMENT SAMPLING AND ANALYSIS 59 4.1 Introduction 59 4.2 Site Selection and Description 59 4.3 Core Collection and Handling 61 4.4 Sediment Core Analysis 68 4.4.1 Environmental Magnetic Susceptibility 68 4.4.2 X-ray Analysis 69 4.4.3 Sediment Analysis 71 4.4.3.1 Bulk Density 71 4.4.3.2 Organic Content 71 4.4.3.3 Grain Size 72 4.4.3.4 Chemistry 76 CHAPTER 5: SEDIMENT CORE DATING 83 5.1 Introduction 83 5.1.1 Dating approach 83 5.2 Caesium Dating 85 5.3 Laminations 86 5.4 Heavy Metal Concentrations 88 5.5 Sediment Texture 89 5.6 Chronological Synthesis 91 5.6.1 Combination of Techniques 92 5.6.2 Extrapolation of Dates to Other Cores 92 CHAPTER 6: SEDIMENTATION RATES AND MARSH DEVELOPMENT 100 6.1 Introduction 100 6.2 Sedimentation Rates 101 6.2.1 1954 to 1996 102 6.2.2 1910 to 1954 106 6.2.3 1894 to 1910 , 109 6.2.4 Prior to 1894 109 6.3 Sedimentation Patterns and Marsh Development 110 6.3.1 Marsh Development: Islands 113 6.3.2 Marsh Development: Front 115 6.4 Conclusion 117 CHAPTER 7: HEAVY METAL: CONTAMINANT STORAGE 120 7.1 Introduction... 120 7.2 Baseline Data 120 7.2.1 Developing Natural State Baselines 121 7.3 Mercury Contamination 123 7.3.1 Historical Use of Mercury '. 124 7.3.2 The Impact of Gold Mining in the Fraser River Basin 124 iv CHAPTER 8: CONCLUSION 129 8.1 Conclusions 129 8.2 Summary of Findings 133 8.3 Further Research 135 REFERENCES 136 Personal Communications 144 Aerial Photographs 145 APPENDICES 146 Appendix 1: Control Points used to create Aerial Photographic Mosaics 146 Appendix 2: Photographs of Core Longitudinal sections 147 Appendix 3: Results of Environmental Magnetism 155 Appendix 4: Results of Sediment Analysis 157 Appendix 5: Results of Heavy Metal Analysis 174 Appendix 6: 1 3 7Cs Analysis Results 178 v L is t of Tables Table 2.1: The main factors controlling sedimentation in the Fraser River delta 17 Table 2.2: Historical high water levels on the Fraser River at Mission and Hope (1876-1996). 18 Table 2.3: Loading summary of copper, lead and nickel in discharges to the South Arm 27 Table 2.4: River training structures in the Fraser River delta (1886-1994) 33 Table 3.1: Hydrographic charts used in this research 45 Table 3.2: Changes in marsh area between 1930 and 1994 54 Table 4.1. Core data 63 Table 4.2: Marsh environments characterised by substrate and vegetation cover 64 Table 6.1: Sedimentation rates for river training periods 102 Table 6.2: Inorganic sedimentation rates for river training periods showing marsh developmental stage 103 Table 6.3: Marsh sedimentation rates based on 1 3 7Cs dates from two studies 104 Table 6.4: Sedimentation rates for marsh developmental stages 114 Table 7.1: Background values of heavy metal concentrations 122 Table 7.2: Heavy metal concentrations from surface sediment 122 Table 7.3: Background and surface heavy metal concentrations for Barber 27 123 vi List of Figures Figure 2.1: The Fraser River delta, located in southwestern British Columbia 12 Figure 2.2: Lateral channel migration across the tidal flats between 1827 and 1912 15 Figure 2.3: Mean annual flow and maximum daily flow at Hope between 1912 and 1996 20 Figure 2.4: Historical dredging activity on the lower Fraser River 30 Figure 2.5: River training structures in the Fraser River delta 34 Figure 3.1: 1827 chart of the Fraser River (British Admiralty Hydrographic Chart) 42 Figure 3.2: Hydrographic charts showing channel change between 1860 and 1946 48 Figure 3.3: 1994 aerial mosaic of the study area 50 Figure 3.4: Marsh development between 1930 and 1994 53 Figure 3.5: Regions of marsh growth 54 Figure 4.1: Location of core sites in the Fraser River delta 61 Figure 4.2. Typical marsh environments in the Fraser River delta 65 Figure 4.3: Core logs from the Fraser delta marshes 66 Figure 4.4: Core logs from the marshes fronting the Fraser River delta 67 Figure 4.5: Environmental magnetism results from Fraser River delta marsh cores 70 Figure 4.6: Organic matter in the Fraser River delta cores 73 Figure 4.7: Grain size distribution in the island cores, Fraser River delta 74 Figure 4.8: Grain size distribution in the cores fronting the Fraser River delta 75 Figure 4.9: Results of heavy metal analysis of cores Barber 27 and Woodward 21 79 Figure 4.10: Results of heavy metal analysis of cores Duck 20 and Duck 31 80 Figure 4.11: Results of heavy metal analysis of cores Westham 29 and Westham 30 81 Figure 4.12: Results of heavy metal analysis of core Lulu 33 82 Figure 5.1: Results from 1 3 7Cs analysis 87 137 Figure 5.2: Examples of correlation between cumulative couplets and 1954 Cs results 88 Figure 5.3: Estimating 1910 in the Fraser delta marshes cores 90 Figure 5.4: Grain size distribution showing sand deposits from large floods 91 Figure 5.5: Results of the combined dating techniques for Barber 27 and Woodward 21 93 Figure 5.6: Results of the combined dating techniques for Duck 20 and Duck 31 94 Figure 5.7: Results of the combined dating techniques for Westham 29 and Westham 30 95 Figure 5.8: Results of the combined dating techniques for Lulu 33 96 Figure 5.9: Dated cores from the islands of the Fraser River delta based on environmental magnetism 98 Figure 5.10: Dated cores from the marshes fronting the Fraser River delta based on environmental magnetism 99 Figure 6.1: Stages of marsh development plotted against the organic content of each core.... 112 Figure 7.1: Mercury concentrations in Fraser River marshes 126 Figure 8.1: Relation between marsh growth, river regime, and river management 130 vii Acknowledgements I would like to thank my supervisor, Dr. M. Church, for his continued support and encouragement. Numerous people have provided invaluable assistance at various stages during this thesis. They include: Diane Pellerin, Daphne Hales, Catherine Griffith, Russell White, Annika White, Christie Steckler, Graham Shivers, Michelle Burfitt, Rebecca Brown, Kelley Hishon, Catherine Isaac, Derek Miller, Darren Ham, Hamish Weatherly, Cole Harris, Margaret North, Michael Roberts, Olav Slaymaker, Hans Schreier, Chris Jeffrey, Simon Dadson, Andre Zimmerman, Hjalmar Laudon, Manon Desforge, Rosemary Cann, Vincent Kujala, and lim Mintha. I apologise to those I have failed to list. Thank you also for your help. Analysis of Environmental Magnetism was made possible by the generosity of Dr. Randy Enkin, who made his lab at the Pacific Geoscience Centre available to me. Dr. Tark Hamilton, also of the Pacific Geoscience Centre, kindly conducted the preliminary, detailed 1 3 7Cs analysis. The remainder of the 1 3 7Cs analysis was done by Dr. Sandu Sonoc of the Department of Chemical Engineering, University of Toronto. 2 1 0Pb analysis was done by Jack Cornett at MYCORE Scientific. The cores were x-rayed by Spencer Dealing of the Radiology Department at the UBC hospital. All of these people provided help with, and insight into, the interpretation of their results. Thank you. Heavy metal chemical analysis was done at Chemex Labs, North Vancouver. Vibrocoring equipment was borrowed from Dr. M. Roberts of the Geography Department, Simon Fraser University. This research was made possible by funding from an Environment Canada Fraser River Action Plan grant awarded to Dr. M. Church, and a grant from the Natural Sciences and . Engineering Research Council of Canada, also awarded to Dr. M. Church. viii CHAPTER 1 INTRODUCTION 1.1 Introduction Deltas may be defined as deposits of riverine sediment that occur at the confluence o f a river and any body o f standing water. The morphology and stratigraphy o f a delta are controlled by a variety o f factors, which reflect the dual nature o f the deltaic environment, coastal and fluvial. The most influential of these are sediment input, fluvial discharge, tidal regime, wave energy, littoral currents and coastal morphology. Changes to any o f these factors w i l l ultimately affect the sedimentological regime of the delta. Deltas have long been a focus of human settlement in coastal areas, providing flat, arable land and good harbours. They also provide vital estuarine habitats for water fowl and fish. A s the ability of humans to alter their environment to suit their needs has increased dramatically during the last century, the impact of such activities is becoming more clearly apparent. In addition to being over harvested and polluted by human activity, many large deltas in the world have been physically altered to establish and maintain shipping channels. A n understanding of the sedimentological response to these physical alterations is necessary in order to ensure that human activity does not affect the deltaic processes that maintain viable habitats and maintain the delta in the face o f changing sea level. Marshes, a vital component of the estuarine habitat, are natural sediment sinks and, as such, provide a good opportunity to study the long term changes resulting from human activity. 1 The goal of this research is to determine the impact of human activity, such as establishing and maintaining an active shipping channel in the Fraser River delta, on the sedimentation in and spatial development of the marshes at the mouth of the river. The remainder of this chapter will identify in more detail the objectives of this study and provide a review of the pertinent literature. Following this, Chapter 2 is devoted to justifying the choice of the Fraser River delta as a study area and to providing the necessary background information about the delta. In addition, a historical time frame for the research is established in Chapter 2. The research has taken two primary directions. The first, a historical approach using maps and aerial photographs dating back to 1827 and 1930 respectively to establish patterns of channel development in the Fraser River delta, will be the topic of Chapter 3. The second approach to resolving the questions presented in section 1.2 is a physical study of the marsh sedimentary record. Chapters 4 and 5 comprise this study. Chapter 6 summarises the results of the field study in terms of sedimentation rates and marsh development, making connections to natural and human-induced historical changes in the delta. Findings secondary to the main purpose of the research are presented in Chapter 7. The final chapter, Chapter 8, provides a summary of the research and the conclusions. In addition, recommendations for further research are discussed. 1.2 O b j e c t i v e s The purpose of this study is to answer the following questions. 1) does human interference in deltaic systems alter marsh sediment deposition rate or the pattern of marsh development within a delta; and, if so, 2) are such changes preserved and identifiable in the sedimentary record; and, if so, 3) can observed changes in the sedimentary record be related to historical events? 2 These questions can be re-written in the form of a hypothesis: human interference in deltaic systems alters the hydraulic and sedimentary processes, resulting in changes to marsh sediment deposition rates and growth patterns within the delta, and evidence of these changes is preserved in areas with continuous sedimentary records and can be directly related to historical events. 1.3 Marsh Dynamics Coastal marshes are vegetated areas which occupy portions of the intertidal zone on most temperate coasts. They develop in low energy areas, behind barriers or spits or in the lee of islands, wherever a stable substrate and an adequate sediment supply exists. Marsh characteristics are determined by a wide variety of factors, the most important of which are local topography and sediment supply, tidal ranges and energy regimes, and indigenous marsh vegetation. Except for certain locations, such as the Fraser River delta, Columbia River estuary, San Diego coast and San Francisco Bay area, the geomorphology of the western coast of North America is not conducive to extensive marsh development (Chapman, 1977). Local geomorphology also controls the type and availability of sediment, a continuous supply of which is necessary to maintain marsh growth. Coastal areas backed by hard, resistant rock will tend to have a very limited supply of sediment and, consequently, marsh deposits are dominated by peat rather than inorganic materials (Orson et al., 1985; Chapman, 1977). In areas with high rates of sediment supply, marsh deposits are primarily inorganic (Orson et al., 1985). The Fraser River marshes are primarily inorganic. The history of marsh development in temperate regions is short in geological terms; marshes which exist today have developed since the last period of glaciation. In the case of the 3 Fraser River delta, which is approximately 8000 years old (Clague and Luternauer, 1991), marshes may have existed along its margins throughout its development. 1.3.1 Marsh Development Three processes can result in the initiation of a marsh: 1) accumulation of marine sediment in protected intertidal areas, 2) submergence of upland areas due to a rise in sea level, and 3) accumulation of fluvial sediments associated with deltaic formations (Orson et al., 1985). Each of these involves the accumulation of sediment in the intertidal area, one of the primary requirements for the establishment of marsh vegetation. Tidal range, which with nearshore topography controls the width of the intertidal area, influences not only the areal extent of marsh development, but also the diversity of plant species. With a large tidal range there is a greater vertical range for plant communities, resulting in greater plant diversity (Chapman, 1977). Thus macrotidal areas with gently sloping shores have the potential for the largest and most diversely vegetated marshes. The Fraser River delta is marginally macrotidal (mean tidal range is 4 m). Different sediment accumulation rates and inundation periods, determining the stage of plant succession, result in various levels of maturity within a marsh. Many marshes can be divided into a low marsh and a high marsh. In some, a middle marsh environment can also be identified. The younger, topographically lower, low marsh is influenced primarily by marine conditions, due to longer and more frequent periods of inundation (Frey and Basan, 1985). In temperate regions, the boundary between the low and middle or high marsh, determined by tidal regime, substrate composition and a topographic break in slope, is often identified by a cliff-like step (Davies, 1980). Such a step occurs in the marshes fronting the Fraser River delta, identifying the boundary between low and middle marsh (Hutchinson, 1982). Observations led 4 Davies (1980) to conclude that marsh steps are the result of wave attack focused at the break in slope between the nearly horizontal high marsh and the sloping low marsh. Youthful marshes, dominated by low marsh, tend to experience rapid lateral and vertical sedimentation and often have a well developed drainage system consisting of meandering creeks. Vegetation zonation in these marshes tends to be simple and there is little species diversity. As a marsh matures, the proportion of high marsh increases. In the high marsh, creeks are mostly filled in and distributed surface runoff is the main method of drainage. With the encroachment of terrestrial vegetation, there is an increasing variety of species. Evidence of succession from low to high marsh has been observed in outcrops of marsh deposits on erosional beaches in South Carolina and Georgia (Frey and Basan, 1985). Hutchinson (1982) provides a description of the low, middle and high marsh environments, and the associated vegetation communities, fronting the Fraser River delta. 1.3.2 Sedimentation and Erosion Sediment in estuarine marshes can be from a number of sources; it can be organic or inorganic, originate from marine, fluvial or terrestrial sources, and it may be transported into or out of a marsh by nearshore or tidal currents, fluvial activity or aeolian processes. Storm activity is very important to sedimentation in estuarine marshes, as is river flooding. Deposits up to 10 cm thick were found along the coastal marshes of Willapa Bay in Washington State following a single storm surge (Reinhart and Bourgeois, 1987). The impact of a storm, either net erosion or net deposition, depends on storm duration, tide and water level at time of storm (Stevenson, 1988; Stumpf, 1983). The majority of inorganic sediment delivered to the marshes of the Fraser River delta is fluvial in nature. In cold regions, such as much of Canada, ice rafting may also play an important role in both transporting sediment into marsh 5 areas and causing erosion (Ollerhead et al., 1999; Dionne, 1989; Scott and Martini, 1982). At present the climate is such that ice does not affect the Fraser Delta. As the elevation of marsh deposits increases and the tidal prism decreases, the ability of tidal currents to carry coarse sediment into marshes decreases, resulting in an upward and landward fining of sediment. Typically, younger, topographically lower marshes have greater vertical accretion rates than higher marshes (French, 1996). However, sedimentation patterns vary over time and between marshes (Letzsh and Frey, 1980; Ranwell, 1964). Most of the work done on the transport of sediment across the intertidal zone by tidal currents has been done on unvegetated tidal flats, the settling lag theory proposed by Postma (1961) being the most well accepted. The movement of sediment in marshes is most likely very similar to the processes discussed in the settling lag theory, but modified by the presence of vegetation, which slows water currents. A detailed account of sediment transport and deposition in a tidal marsh is given by Leonard (1997), who found that a combination of tidal creek geometry and position, and tidal stage control marsh sedimentology. Stevenson et al. (1988) provide a useful review of sediment transport processes in marshes along the eastern coast of the United States. Frey and Basan (1985) identified seven ways in which plants and animals induce sedimentation and reduce erosion: 1) plants reduce wave and current action; 2) vegetation creates eddies and causes deposition in lee areas; 3) some plants enhance clay flocculation by creating highly saline micro-environments; 4) roots help bind the surface, which is of particular importance along channels; 5) algal, bacterial and diatom films help trap sediment and stabilise the surface; 6) animals, such as bivalves, provide a rigid framework which induces sedimentation; and 7) invertebrate filter feeders trap inorganic and organic particles and deposit them as faeces. Erosion is most prevalent in two areas of a marsh, along the tidal channels and at the seaward edge. The main causes of erosion along creek banks are current scour and plucking of 6 sods, slumping of steep banks, and bioturbation (Letzsch and Frey, 1980). The front edge of a marsh is most susceptible to slumping resulting from wave erosion and undercutting, as has been noted along the marshes fronting the Fraser River delta by Williams and Hamilton (1994). They interpreted this phenomenon as an indicator of marsh deterioration. Overgrazing and trampling of marsh vegetation, for example by geese and muskrats, can also lead to erosion (Stevenson et al., 1988; Dionne, 1985). 1.4 Changing Relative Sea Level The maintenance of a marsh in an environment of rising relative sea level will occur only if the sedimentation rate is able to balance, or offset, the rate of sea level rise (Reed, 1990). Maintenance does not necessarily occur in situ, but may involve encroachment of the marsh onto adjacent land. In areas where landward expansion of the marsh is restricted by steep or rocky slopes or by artificial barriers, such as dykes, rising sea level may result in narrower marsh zones. Upward growth of the marsh may be accomplished by inorganic or organic material. In some cases, marshes are able to withstand rising sea levels by utilising sediment eroded off the front of the marsh, resulting in a retreat of the marsh's seaward margin, but an overall survival of the marsh (Reed, 1988) Natural subsidence, due to the compaction of marsh sediments under their own weight, may result in a relative rise in sea level. Over several thousand years silty marsh sediments with an original porosity of 80 to 90 % may be compressed to one fourth of their original thickness, while sediments with a higher organic component may be compressed to an even greater extent (Harrison and Bloom, 1977). For example, Harrison and Bloom (1977) found that over 7000 years the deposits of Connecticut coastal marshes had been compressed to 13 % of their original thickness under 10 m of overburden. 7 In areas of falling relative sea level, marshes may become stranded above the tidal limit, at which point a transition to a terrestrial environment occurs (Reed, 1990). Pethick (1981) suggests that typically the upper limit of vertical marsh growth is about 80 cm below the level of the highest annual tide. Falling sea level may result in marshes relocating seaward as growth occurs along the marsh front and terrestrial species take over the landward marsh. Similarly, terrestrial species may become established on marshes as a result of aggradation exceeding the upper vertical limit of marsh vegetation. Supra-tidal sedimentation as a result of high river stage in estuarine marshes may enhance this process. 1.5 Marshes and Human Activity Marshes, with their supporting vegetation, tend to be the most stable of the intertidal environments and, because of this, have frequently been used to study past environmental conditions. Research connecting marsh development and human activity can be divided into two groups. The first uses indicators of human activity as a technique for dating marsh sedimentary sequences. The second explores the impact of human activity on marsh development. A variety of techniques is used for dating marsh deposits, such as radioisotope analysis using 2 1 0Pb and 1 3 7Cs (see sections 5.1.1 and 5.2) (i.e. Cundy et al., 1998; Orson et al., 1998; Bunting et al., 1997; French, 1996; Allen et al., 1993; Bricker-Urso et al., 1989; DeLaune et al, 1989), pollen analysis (i.e. Bunting et al., 1997), storm deposits (i.e. Warren and Niering, 1993; Orson et al., 1990), foraminifera and diatoms (i.e. Bunting et al.,1997), sediment contamination (i.e. French, 1996; Bricker-Urso et al., 1989), artificial surface markers (i.e. Orson et al., 1998), human artefacts (i.e. French, 1996; Allen et al., 1993; Ritter et al., 1972) and historical records (i.e. Allen et al., 1993). At least two independent techniques are required to confirm dates (Allen et al., 1993). Several of these dating methods involve identifying the results of a known human 8 137 • * activity. Cs is radioactive fallout from nuclear testing. Pollen analysis can provide dates through the identification of introduced plant species and the decline of native species due to land clearance. Pollution and human artefacts, such as sawn timber and pottery, can provide dates if the time of introduction to the marsh is known. Artificial surface markers are a deliberately constructed dating technique. Marker material, such as glitter, is deposited on the marsh in order to provide a datable level in the future. While the link between human activity and marsh research is evident, the use of human activity for dating does not, and is not designed to, explore the impact of human activity on marsh dynamics Most research exploring the impact of human activity on estuarine and deltaic systems deals with water quality, pollution (i.e. Skowronek et al., 1994; Coakley et al., 1993; Allen and Rae, 1986; Yim, 1976) and the destruction of natural habitat (i.e. Gagliano et al., 1975; Gagliano, 1973). Only a few researchers specifically have looked at the impact of human activity on the rate of sedimentation. Cundy et al. (1998) found that a rapid increase in sedimentation in a microtidal Sicilian salt marsh pre-dated the main industrial period in the area and, consequently, concluded that the sedimentation reflected fluvial and catchment processes, not human activity. Similarly, a study of a sedimentary sequence in a marsh on Lake Erie, Ontario, found that, while European settlement had a marked impact on upland areas, it did not seem to have been significant in marsh development (Bunting et al., 1997). Recent road construction, however, had a locally pronounced effect on the marsh. Conversely, Kelly et al.(1988) state that many marshes formed along the eastern coast of the United States during European colonisation as a result of increased sediment supply due to early deforestation and agriculture. However, Kelly et al.(1988) provide no evidence of this change in sediment supply in the marsh sedimentary record. Along the Louisiana coast, a study of the impact of canals on marsh accretionary processes suggested that canals have a greater impact on marsh hydrology 9 than on sedimentology (DeLaune et al., 1989). These studies suggest that, while the link between human activity and marsh sedimentation rates has been made theoretically, the evidence of such a link has not yet been successfully identified in the sedimentary record of estuarine marshes. Establishing control sites for research on human impact on marshes can be challenging. The most common approach is to use a marsh with similar natural dynamics to the one under investigation. This approach was successfully used by DeLaune et al. (1989) on the Louisiana coast. Schropp et al. (1990) sampled estuarine sediments from remote areas of coastal Florida in order to identify natural heavy metal concentrations against which to compare samples taken from industrial areas. Deely and Fergusson (1994) used a similar approach to establish control data for a study of post-European settlement metal concentrations in a New Zealand estuary. The effects of human activity are so far reaching, however, that it is often very difficult, if not impossible, to locate unaltered marshes to act as control sites. One potential solution is to use buried marsh sediments pre-dating human activity in order to acquire control data. Luternauer (1977) suggests that sediment cores may be used to determine long term sedimentation rates in order to identify fluctuations in modern sedimentation related to human activity. This research attempts to show the direct impact of human activity on marsh sedimentation rates through the examination of cores. The impact of human activity on lateral marsh growth is studied through historical maps and aerial photographs. 10 CHAPTER 2 FRASER RIVER DELTA 2.1 Introduction The Fraser River delta (Figure 2.1), a sand-dominated deposit of 975 km2 area with an average thickness of 110 m, was formed by the Fraser River, which drains over 250,000 km2 of British Columbia (McLean and Church, 1999; Milliman, 1980). The delta is a good location for studying the impact of human activity on deltaic sedimentation because of the relatively recent history of significant human intervention in this system. This is due to the fact that settlement of the delta area by non-native people occurred only after the mid 1800s. By the time there was a need for establishing a navigable shipping channel up the Fraser River, the technology required for constructing large engineering projects and for dredging was readily available. The assumption is made that the native population had neither the need nor the means to drastically alter the physical state of the delta. Thus the Fraser River delta was transformed within a few decades from a natural, unaltered system to one controlled by large-scale human activity. Such a dramatic transition ought to be more visible in the sediment record than the slower transition that would have occurred in a delta with a longer history of intervention. Pre-intervention data from the sediment record will be used as an unaltered, natural control for comparison with that of the modified delta system. 11 12 The recent settlement of the Fraser River delta by non-native people, and the delta's importance to the Greater Vancouver Regional District, the heavily populated area which developed on and around it, also mean that there are fairly good records of channel configuration, river discharge and sediment load throughout much of the period of human intervention. This information forms a very good data base of background material, unavailable for many other deltas. Within the Fraser River delta, the research area was confined to the mouth of the main channel, namely the South Arm. While the North Arm is also used for navigation, and has consequently undergone river management, the majority of the river engineering work has focused on developing and maintaining a deep water shipping channel in the South Arm. The remainder of this chapter provides a review of the relevant literature on the Fraser River delta and gives the background information necessary for this study. First, a review of pertinent literature on the natural history and processes of the Fraser River delta is presented. This is followed by a brief outline of human history on the delta. Finally, the history of river management is documented. Since river management is inextricably linked to natural channel development, channel migration since 1860 will also be discussed. 2.2 N a t u r a l H i s t o r y and Processes Research on the Fraser River delta relevant to this study falls into four categories: 1) development and structure of the delta; 2) deltaic processes; 3) sedimentation and changes in the intertidal and subtidal areas; and 4) impact of human activity. 13 2.2.1 Development and Structure of the Delta A great deal of research has been done on the development of the Fraser River delta, primarily through the interpretation of sediment cores (i.e.; Monahan et al., 1993; Clague and Luternauer, 1991; Roberts, 1990; Williams and Roberts, 1989; Williams, 1988; and Clague et al., 1983). Their work has provided an understanding of the growth of the delta since the last glaciation and of the structure of underlying sediment facies. Radiocarbon dated wood from prodelta deposits beneath the delta apex, situated near New Westminster, indicates that the delta is a Holocene landform since the terrestrial surface emerged approximately 9000 years ago (Williams and Roberts, 1989). The subaerial delta now extends 23 km westward from its apex, where the Fraser River leaves the confines of Pleistocene uplands. Intertidal flats fronting the delta on its western edge, are up to 9 km wide, while the subaqueous delta plain is a further 2 km in width. The delta foreslope descends at an average angle of 1.5° into the Strait of Georgia (Monahan et al., 1993b). The southern delta front facing Boundary Bay is now inactive, separated from the mouths of the distributary channels by Point Roberts. A typical delta structural sequence is described by Roberts (1990), who found three major units in the northern section of the delta. The lowest unit (50 m thick) consists of fine to medium grained silts often interbedded with sand, originating in a delta front environment. The middle unit (5-25 m thick) is composed of well sorted medium to coarse grained sand, deposited on tidal flats. The upper layer consists of 1-2 m of intertidal silts, mantled by organically rich floodplain silts. Monahan et al. (1993b), Williams and Roberts (1989) and Mathews and Shepard (1962) describe similar findings. The nearly continous sand sheet underlying the upper delta plain was created by lateral migration of distributary channels across the delta tidal flats (Monahan et al, 1993b). Such 14 lateral migrations of distributary channels during the 1800s and early 1900s are shown in Figure 2.2. Abandoned channel systems, which once drained into Boundary Bay, have been reconstructed by Hutchinson et al.(1995). Radiocarbon dates from the base of a relic channel immediately south of Canoe Pass indicate that the channel existed in this location in the 18th century (Clague, 1996 pers. com.). All of this evidence indicates that prior to human activity the deltaic reaches of the Fraser River shifted channel position relatively regularly, raising the question of how channel control has affected delta growth. While developing a clear Figure 2.2: Lateral channel migration across the tidal flats between 1827 and 1912 (Public Works Canada, 1947). 15 understanding of the large-scale internal stratigraphy of the delta and its paleogeography, these studies do not provide the detail necessary for analysing the stratigraphy of the modern intertidal areas of the Fraser River delta. Clague et al. (1983) have identified a more detailed sedimentary sequence in the Fraser River delta, which proceeds from fine grained or sandy foreslope deposits through fine to medium sands of the intertidal environment and coarser sands of river channels, to mud or peaty silts of the floodplain. The intertidal facies, those of interest to this study, were found to be horizontally stratified with cross-bedding and bioturbation structures. Another useful account appears in the study by Gibson and Hickin (1997) of the Squamish delta, approximately 40 km north of Vancouver, which provides a facies model for intertidal marsh and sand flats. This study identified marsh deposits of alternating organic and inorganic annual couplets, overlying alternating sequences of fine and coarse laminae containing fine tidal rhythmites, attributed to intertidal sand flats. Similar structures have been observed in the Fraser River delta (Clague et al., 1983; Luternauer and Murray, 1973; Johnston, 1921). Swinbanks and Murray (1981) and Kellerhals and Murray (1969) also observed similar features in the intertidal zone of Boundary Bay. However, given that Boundary Bay is not influenced by a freshet and is dominated by winter storm activity, the system is different to that around the mouth of the Fraser River. 2.2.2 Deltaic Processes Three natural processes control the river regime in the deltaic reaches: fluvial discharge, tidal activity and sediment input. The first comprehensive overview of the Fraser River delta processes was presented by Johnston (1921). The main factors controlling sedimentation in the Fraser River delta are summarised in Table 2.1. 16 The Fraser River at Hope, the gauging station with the longest record (149 km upstream from the study area), has an annual mean discharge of 2,700 m V 1 . The river exhibits strong seasonality and the mean annual flood, which occurs during the freshet (May to July), is 9,790 m Y 1 (McLean et al., 1999). Flood levels have been recorded since the late 1800s (Table 2.2). In such a large and sparsely populated basin, most land uses are not likely to have a serious effect on either runoff or sediment yield (Church et al., n.d.). A possible exception is hydraulic gold mining which moved huge quantities of sediment in the Fraser River basin during the gold rush (late 19th century) (see sections 3.41 and 7.3.2). . Table 2.1: The main factors controlling sedimentation in the Fraser River delta. Freshet (May to mid July) Non-Freshet Discharge (at Mission) 3 410 mY1 (mean) 9 790mY' (mean) 17 200mY' (maximum: 1894 estimate) >1 500 mY1 Sediment Load (at Mission) 17 x 106 tonnes/year (mean) * 80% of sediment load transported 40-50% is sand Silt and clay dominate sediment load Tides ** 4 m at Sand Heads Tidal fluctuations restricted to below Mission (85 km upstream). Salt intrusion restricted to tidal flats. Tidal fluctuations felt at Sumas Mountain (95 km upstream). Salt water intrusion may reach New Westminister (35 km upstream) * Sediment load (1966-1986) at Mission consisted of: 17.9% sand (> 177um) 47.7% silt 18.8% sand (<177um) 15.5% clay ** Freshet tidal data is for flows exceeding 5 000 mY1 (data from McLean et al., 1999; Public Works Canada, 1989; Milliman, 1980) The nature of the Fraser River drainage area determines not only the characteristics of the discharge, but also that of the sediment load. The sediment sources of the Fraser River, which drains a glaciated, mountainous area, are primarily glacial till, glaciolacustrine silt, earth flows, and silty debris flow deposits. 17 Table 2.2: Historical high water levels on the Fraser River at Mission and Hope (1876-1996). Date Stage (m) Hope Mission Discharge (nrVs) Hope Mission Date Stage (m) Hope Mission Discharge (nrVs) Hope Mission 1876 7.001 1950 9.909 7.451 12 500 1882 - 7.34' - - 1955 9.391 - 11 300 1894 - 7.921 - 17 2002 1957 9.040 - 10 400 1905 - - - - 1964 9.601 7.01' 11 600 -1913 9.205 - 10 300 - 1967 9.312 - 10 800 13 500 1920 8.931 - 10 800 c 1972 10.141 7.077 12 900 14 400 1921 9.083 - 11 100 - 1974 9.318 6.770 10 800 13 100 1928 9.174 - 10 300 - 1986 9.216 6.137 10 600 12 400 1936 9.525 - 10 600 - 1990 - - 10 100 10 800 1948 10.973 7.611 15 200 Hope is 77 km upstream from Mission. - Indicates missing data. 1 Data: Northwest Hydraulic Consultants, 1999 2 Data: McLean et al., 1999 all other data: Environment Canada, 1999. Consequently, the sediment load is dominantly fine grained. A mean annual total sediment load of the Fraser River has been calculated by McLean et al. (1999) based on data from the Mission gauging station (1966 to 1986), which provides a good estimate of sediment input into the estuary. Mean annual total suspended sediment load is 17 million tonnes/year, consisting of approximately 36 % sand, 48 % silt and 16 % clay. The majority of the total sediment load (80 %) is transported between May and July, the freshet months, and the highest sediment loads occur in the highest discharge years. For example, the total suspended sediment load at Mission in 1972 (high flow: 12,900 m3/s) was 31 million tonnes (sand 44%, silt 42 % and clay 14%), while in 1983 (high flow: 8,490 m3/s) the total suspended load was only 8 million tonnes (sand 33%, silt 50 % and clay 17%). It is interesting to note that the sand content in suspension is higher during high flow years. During the non-freshet months, the discharge is lower and the sediment load is dominated by silt and clay (Milliman, 1980). Bed material in the lower reaches of the Fraser River is fairly uniform: median grain size ranges between 250 um and 350 um, and typically 97 % of the bed material is coarser than 125 um, while 92 % is coarser than 177 um 18 (Public Works Canada, 1989). The data available are insufficient to determine the division of the sediment load between the various channels of the Fraser River, however the South Arm is estimated to carry 91 to 97 % of the total load below New Westminster (Public Works Canada, 1989). Long-term trends in the Fraser River flow regime are significant to this study, because of the correlation between discharge and sediment transport capability. Cumulative annual departures in mean flow, calculated for the period between 1912 and 1996, show that there have been abrupt shifts in the regime (Figure 2.3). Between 1925 and 1948, mean flow levels were lower than average, while they were higher than average between 1948 and 1977. From 1977 to 1996, flow levels were again lower than average. A similar trend is visible in annual maximum daily flow levels. During periods of lower than average discharge, less sediment is transported and, consequently, less is available for marsh aggradation. Conversely, during periods of higher than average flows, more sediment is potentially available for deposition on the marshes. McLean and Tassone (1991), Public Works Canada (1989) and Northwest Hydraulic Consultants (1999) have developed sediment budgets for the years 1963 to 1974,1974 to 1984, and 1996 to 1997, showing that, in response to the dredging program, the river has degraded, lowering the bed an average of 8 - 12 cm/a (or 2 - 3 m over 25 years) between New Westminster and Sand Heads. The results of this research indicate that, during periods of high peak flows, the river's capacity to transport sediment is greatest, as was the case during 1963 to 1974. In 1997, a year with a high freshet and relatively low dredging, net aggradation occurred along most of the channel, indicating that during high flow years the river's increased capacity to move sediment results in overall net sediment deposition (Northwest Hydraulic Consultants, 1999). 19 15000 annual maximum daily flow 10000 (m'/s) mean 8676 m'/s , J , 5000 cumulated annual departures Q (maximum daily flow) -5000 mean flow (m'/s) (mean flow) 3000 2000 1000 cumulated annual Q departures 000 2000 -| -3000 -4000 -5000 year 1910 1930 1950 1970 1990 Figure 2.3: Mean annual flow and maximum daily flow at Hope between 1912 and 1996.Cumulated departures from the mean show periods of higher and lower than average flow: descending plots indicate persistently below average flow and ascending plots indicate persistently above average flow (McLean and Church, 1999; Environment Canada, 1999). The research also reveals that during 1974 to 1984 the volume of sediment removed by dredging greatly exceeded that of the total bed material load entering the system at Mission (dredging quantity: 46.1 x 106 tonnes; bed load material: 26.5 x 106 tonnes). This research only addresses the navigation channel, and does not attempt to explore the impact of dredging or the effect of high peak flows on side channels, sand flats and marshes of the delta, which are major sediment storage areas. Understanding how sediment moves into these areas is significant in defining a sediment budget for the Fraser River. 20 The Strait of Georgia is a macro-tidal environment, with a tidal range of up to 4 m at the edge of the Fraser River delta. The tidal reach of the Fraser River varies with flow: at low flow the effect of tides can be felt 98 km up the river, while at high flows tidal variations are restricted to the area downstream of Mission (85 km up the river). Similarly, the salt water intrusion into the river, or salt wedge, reaches further upstream, to New Westminster (35 km from Sand Heads), during low river flows and is pushed out to the tidal flats during the freshet (McLean and Tassone, 1991). Within the mouth of the river the tidal prism is large and, consequently, tides play a major role in forming the currents around the islands in this area. Changing relative sea level also affects the Fraser River delta. The impact of sea level change on delta growth has been studied in detail by Williams (1988). Delta settlement, due to sediment compaction, is in the order of 1.45 mm/a, according to geodetic levelling of the delta (Mathews et al., 1970). This rate, in combination with local isostatic subsidence of 0.76 mm/a and a global sea level rise of 1.49 mm/a (Gornitz, 1995), provides a relative sea level rise of 3.70 mm/a for the Fraser River delta. Future rates of sea level rise are expected to increase. An increase in global sea level of 48 cm by 2100 (4.44 mm/a) was the "best guess" scenario of the International Panel on Climate Change in 1992 (Gornitz, 1995). Historical sea level change along the coast of British Columbia is summarised by Clague et al. (1982). 2.2.3 Sedimentation and Changes in the Intertidal and Subtidal Areas A summary of the current trends of advance and retreat of the Fraser River delta foreslope is provided by Hoos and Packman (1974). Later work by Tassone (1990) indicates that on average the -90 m contour of the delta foreslope has advanced 4.5 m/a between 1932 and 1974, with even greater advance rates at the river mouths. The -10 m contour has remained relatively stable, except along the southern delta front where it appears to be retreating. Slope 21 failures along the delta foreslope have also been studied in attempts to identify sea-floor hazards in an area of significant human use (Barrie, 1999; Hart and Barrie, 1995). Much of this research is in response to the growing awareness of the potential for earthquakes and tsunamis in the area (i.e. Kulikov et al., 1999; Clague et al., 1992). Tidal flats, or sand flats, occupying extensive areas off the front of the subaerial delta, are mantled in well sorted sand (125 to 350 um) and slope gently seaward (approximately 0.05°) (Luternauer, 1980). The sedimentation pattern in this area has been defined using surveying techniques, core sampling and aerial photography (Luternauer 1977, 1976, 1975; Luternauer and Murray, 1973). Further research on the sand flats has focused on the distribution of pollutants (i.e. Feeney et al., 1994; Grieve and Fletcher, 1976). Research has also been done on the intertidal zone of Boundary Bay, an inactive section of the delta, which currently receives no sediment from the Fraser River (i.e. Swinbanks and Murray, 1981; Kellerhals and Murray, 1969). These studies defined the various bio-sedimentary zones across the intertidal area, finding that the primary control is elevation, which determines inundation levels. These studies also indicate the difference in environment between Boundary Bay and the active delta front. The Boundary Bay environment is sandy and saline, as opposed to the clay and silt rich brackish marshes of the Fraser River. This fact, in addition to a complete lack of freshet influence, distinguishes the Boundary Bay system from that of the Fraser River. Although these studies deal with modern sedimentary processes, and acknowledge that these may be influenced by human interference in delta processes, they do not and are not designed to prove such a connection. Luternauer (1977) and Luternauer and Murray (1973) both indicate a need to determine sedimentation rates for the intertidal areas, and suggest that coring deeper than their 1 m cores may provide information about the natural fluctuations in sedimentation rates. Such information would enable researchers to distinguish between the 22 consequences of human activity and those of natural fluctuations. This research attempts to determine such information for the marshes of the Fraser River delta. The majority of research conducted in the marshes of the Fraser River delta is biological in nature, concerned with species distribution and dynamics (i.e. Grout et al., 1997; Patterson, 1990; Hutchinson, 1988 and 1982). The marshes in the lower Fraser River delta exist in three areas. One area of marshes lies landward of the sand flats, running parallel to the subaerial delta, occupying a zone approximately 1 km wide near the high tide level. The intertidal islands within the river mouths comprise the second group of marshes, and the third group exists as fringing marshes along the banks of the river channels. Except for those existing in Bounday Bay and south of the Roberts Bank Coal Terminal, which are areas isolated from fresh river water, the marshes of the lower Fraser River delta are brackish in nature, and should not be classified as either salt marshes or fresh water marshes. Marsh plant communities and associated ecological zones, high marsh, middle marsh and low marsh, are described in Chapter 4 (see Table 4.2). 2.2.4 Impact of Human Activity The only study to directly address the effect of river management on Fraser River marsh sedimentation is that by Williams and Hamilton (1995). Using 1 3 7Cs to determine 1954 and 1964 levels in shallow trenches dug in the marshes fronting Lulu Island, they concluded that sedimentation rates had dramatically decreased from 1954 to 1994 (see section 6.2.1 for more detail). While being a very useful study, as it establishes post-1954 sedimentation rates, the conclusion, which attributes this decline in marsh sedimentation rate to dredging and engineering structures, must be considered with caution. The study does not take into account that the 1954 to 1964 sedimentation rates may have been unnaturally high as the marsh adjusted to new environmental conditions created by river management. Further research into historical marsh 23 sedimentation rates is needed to determine natural rates in this area, before statements about the impact of river management can logically be made. In his paper on the consequences of training walls and jetties on the aquatic environments and macroinvertebrates of the Fraser and Squamish estuaries, Levings (1980) identifies three changes in the Fraser intertidal area resulting from human activity. He notes that the dumping of dredge spoils on the upper intertidal zone has altered the sediment distribution across the marshes and sand flats. This dumping occurred between the Iona Causeway and the North Arm Jetty, and is, consequently, not within the area of concern to this research. Secondly, he notes that scour holes have formed in the vicinity of the jetties as a result of constricted ebb tidal flow. And finally, Levings suggests that the expansion of the Sturgeon Bank marsh (see section 3.4.2) and the sand waves on the tidal flats may be the consequence of wave refraction due to the jetties. Another area of research concerned with the consequences of human activity on the Fraser River delta is that of sediment and water pollution. Since the 1970s, several studies have documented changing concentrations of numerous chemicals in the delta (i.e. Feeney et al., 1994; Swain and Walton, 1993; Standi, 1980; Grieve and Fletcher, 1976). Dorcey (1991) provides a good review. Although the situation over the last 30 years is understood, there is little information about the natural levels of many of these pollutants in the delta. Consequently, as with sedimentation rates, there is a need to obtain information about the delta state prior to human intervention in order to accurately assess the impact of human activity. An attempt to create such background information, secondary to the goals of this research, is presented in section 7.2. 24 2.3 H u m a n His tory 2.3.1 Native Populat ion The indigenous population of the Fraser River delta prior to European contact consisted of the Tsawwassen and Musqueam peoples (Harris, 1992). Numerous other peoples, such as the Kwantlen, Cowichan, Nanaimo, and Saanich, arrived at the delta to fish during the summer. Seasonal villages of plank houses were located at various sites around the delta. Late in the summer, several thousand people travelled up the Fraser River to fishing grounds in the Fraser Canyon. On returning through the delta, many collected Indian potato or Wapato (Sagittaria latifolia) from the delta marshes (Harris, 1992). Despite this activity in the delta, there is no evidence to suggest that the indigenous peoples physically altered the delta morphology beyond local disturbance around villages and food collection sites. Consequently, for all intents and purposes, the delta was unmodified from a natural state when Europeans arrived. 2.3.2 European Discovery and Settlement The first non-native documented sighting of the Fraser River delta was in 1791 by the Spanish explorers, Jose Maria Narvaez and Don Francisco Elisa, governor of Nootka Sound. They sketched the location of the river, but did not explore it. The following year both a Spanish expedition, led by naval officers Dionisio Galiano and Cayetano Valdes, and a British expedition, led by Captain George Vancouver, entered the Strait of Georgia, but again failed to explore the Fraser River beyond the tidal flats. In 1808 Simon Fraser travelled down the Fraser River from the interior, but failed to reach the Strait of Georgia. In 1827 the first non-native settlement in the area was established by the Hudson's Bay Company, with the construction of Fort Langley, 60 km up river from the mouth. Initial settlement and farming were concentrated in the area around the fort. 25 The first farm in the delta was that of Hugh McRoberts, located on Sea Island in the North Arm of the river (Ross, 1979). The Ladner family became the first to farm on the south side of the river below Fort Langley when they settled near Chalucthan Slough in 1868, the site of present-day Ladner. In his memoirs compiled by his daughter in 1979, Ellis Ladner, born in 1871, describes the delta as a prairie with tangled grass hummocks and hardhack (Spirea douglasii). Along slough and river banks, where the soil was more productive than on the prairie, grass, clover, hazel, willow, crab apple and alder grew. Fir and spruce were found along some sloughs at a distance from the main river channel (Ladner, 1979). Another clue to the condition of the delta is given in this description by Ellis Ladner: "Without dykes, almost any full-moon tide overflowed the land for a considerable distance, and the receding tide took only the bulk of the water from the land. Without drainage, the excessive moisture in the soft ground of the prairie disappeared only by evaporation" (Ladner, 1979, p.37). Thus, terrestrial areas in the mouth of the delta were still flooded monthly along their margins in the late 1800s. 2.3.3 Industr ial Development: Pollut ion Industrial and urban activity developed very rapidly in the delta, making it difficult, if not impossible, to accurately attribute specific pollutants to specific industries. The first industries in the Fraser River delta, such as agriculture, fish canning, ship building and wood preparation, would probably only have polluted very localised areas. Today pollution is wide-spread. Stancil (1980) provides a summary of the origins of selected heavy metals discharged into the lower Fraser River (Table 2.3). Primary sources are stormwater drains and sewage treatment plants. Automobile traffic produces a significant amount of pollution in the Fraser Valley, and contaminated runoff from roads reaches the river via storm drains (Schreier, Dec. 1997 pers. com.). 26 Table 2.3: Loading summary of copper, lead and nickel in discharges to the South Arm, Fraser River. Total Copper (kg/d) Total Lead (kg/d) Total Zinc (kg/d) Municipal Landfill Leachates 0.18 0.13 3.07 Industrial Discharges 0.14 0.40 0.20 Sewage Treatment Plant Discharges 103.9 36.90 84.10 Stormwater 14.5 50.0 30.0 (data from Standi, 1980) Prior to the opening of the Iona Island Waste Water Treatment Plant in 1963, there was no sewage treatment in Greater Vancouver. Sewage was discharged directly into the most convenient body of water. Discharge water from Iona, located at the mouth of the North Arm, contaminated the intertidal area fronting the delta until a deep water discharge was constructed in 1988. Other treatment plants which affect the study area are the Lulu Island and Annacis Island plants, opened in 1973 and 1975 respectively. A sewage lagoon, built in the marsh opposite Ladner in 1963, would also have influenced the study area until it closed in 1980, after which it continued to be used for several years on an emergency basis (Giuliani, Dec. 1999 pers. com.). Water and sediment contamination in the Fraser River delta can be divided into two groups: heavy metals such as lead, zinc and copper; and synthetic organic compounds such as chlorinated hydrocarbons (including pesticides and wood preservatives). In this study, heavy metal pollutants are of more interest than synthetic organic compounds, because the latter did not come into widespread use until the latter half of the twentieth century. 2.4 Physical Alteration of the Delta In addition to chemically altering the delta sediments through pollution, non-native settlement of the area has resulted in rapid physical alteration through river management. River 27 management in the Fraser delta consists of four activities, dyking, snag removal, dredging and river training. 2.4.1 Dyking Initiated in the late 1800s, as land owners strove to protect individual plots of land from inundation, dyking is now an integrated municipal effort which protects approximately 55 000 ha to the 1894 flood level (Fraser Basin Management Program, 1994). 90 % of river channels in the Fraser Valley are now dyked (Milliman, 1980). This activity has successfully removed the terrestrial portion of the delta from the fluvial system, except during extraordinarily large flood events. Large areas of marsh have been lost as a result of dyking and draining the land. Prior to dyking, the terrestrial areas of the delta consisted of marsh, peat bog, prairie, deciduous forest and coniferous forest. The exact area of marsh environment in the delta prior to dyking is unknown. Estimates of marsh distribution in the mid 1800s have been made using early surveyors' notes (North et al., 1979) and pre-dyking inundation patterns based on modern contour lines (Forrester et al., 1975, in Fraser River Estuary Study Steering Committee, 1978). Unfortunately, neither study can be used to determine marsh area. In the first, surveyors' criteria for distinguishing marsh from terrestrial environments are unknown, and the seaward limit of marshes was not surveyed. The second study, which identified potential areas of marsh habitat using modern contour lines and known habitat requirements, unfortunately used a base-map from the 1970s. As a result, large areas of marsh were included which did not exist in the mid 1800s. For the purpose of this study, the portion of the delta now protected by dykes is considered lost to the deltaic system, and consequently will not be considered. 28 2.4.2 Snag Removal Snag removal, the removal of logs, tree stumps and other debris hazardous to shipping, began in 1882. The number of snags removed each year averaged between 200 and 300. Although snag removal has definitely altered the appearance of the intertidal areas, the impact of this activity on the marshes is unknown. When Captain Vancouver saw the front of the delta in 1792, he described the delta front as a shoal which "continues along the coast to the distance of seven or eight miles from the shore, on which were lodged, and especially before these [river] openings, logs of wood, and stumps of trees innumerable" (as quoted in Ross, 1979). Johnston (1921) also mentions large volumes of drift wood in the river during the freshet, which collect in the river channels and "along the shore face of the delta" (the marshes?). The sand flats, he notes, were remarkably clear of debris in the early 1900s. Today very few logs or stumps are seen. A boom, the Agassiz debris trap, constructed in 1979, replaced boats as a means of removing floating debris from the river. On average 90 000 m3, which is approximately 90 to 93 % of wood debris in the river, is caught in the trap each year (Zak, Jan. 2000 pers. com.). 2.4.3 Dredging Dredging, to establish and maintain a navigable channel between the Strait of Georgia and New Westminster, began in 1880. Since this time dredging has continued annually, resulting in a deeper channel. Historical dredging activity is shown in Figure 2.4. Prior to 1957 most dredging was carried out by Public Works Canada, with little or no borrow (contract) dredging. Between 1958 and 1960 records are only partially complete. From 1961 to 1974 dredge records are complete, but the borrow records are not; however it is unlikely that borrow dredging constituted more than a very small amount. After 1974 all records are complete (Northwest Hydraulic Consultants, 1999). 29 Sediment budgets developed for the lower Fraser River indicate that between 1974 and 1984 dredge volumes exceeded natural bedload incoming volumes by a factor of nearly two (McLean and Tassone, 1991; Public Works Canada, 1989). Between New Westminster and Sandheads, dredging has lowered the river bed an average of 8 -12 cm/a since the 1960s (Northwest Hydraulic Consultants, 1999). Dredging has also had an impact on areas outside the main navigation channel: upstream areas and side channels have deepened in response to the deeper main channel. Deepening the navigation channel has also changed the distribution of current velocities across the channel (Northwest Hydraulic Consultants, 1999). However, since most of the marshes are not located immediately adjacent to the main channel, these changes in velocities may not affect marsh areas. Fraser River Dredging Activity 7 -| 6 average 5 ^ per year over 4 - 15 years 3 - ^ \ 2 -1 -0 -i ^  T U-Average dredging (m /a x 10 ) South Arm North Arm 1961-1974 1.636 0.225 1975-1991 4.698 0.389 1992-1996 2.093 0.005 l l l l I I I T~T llll I I I I I I I I O 2 S ~ ON O - T t OO 0\ ON C \ O >/-) ON o vo ON o ON o\ o oo ON o ON ON Year (data from Northwest Hydraulic Consultants, 1999; Public Works Canada 1989 and 1957) s Navigation H Borrow (records lost prior to 1975) Figure 2.4: Historical dredging activity on the lower Fraser River. On the other hand, lowering of the river bed by dredging has resulted in an overall drop in water level. Tidal guages at Steveston and New Westminster show that Fraser River water levels have decreased since the mid 1960s, while the tidal gauge at Point Atkinson (at the mouth of the outer part of Vancouver Harbour) shows no such trend (Northwest Hydraulic Consultants, 30 1999). This decrease in river water level due to a deeper main channel, causes an increase in the tidal prism, which, in turn, results in greater tidal current velocities (Tarbotton, June 1999 pers. com.). Increased tidal velocities and decreased river water level would decrease sediment transport and deposition in the marshes. Dredge spoils have been traditionally dumped in four locations: within the river, on the subaqueous delta front, at deep water dumping sites, and on land as construction fill. With the exception of dumping spoils back into the river channel, all of these disposal methods effectively remove the dredge material from the deltaic system. Between 1974 and 1984 only 7% of dredge material was deposited in the river (Public Works Canada, 1989). Prior to human activity, much of the bed material would have been available for transport across the delta front by longshore currents. In 1987 dredge spoil was dumped on the sand flats immediately behind the west end of the bend in the Steveston North Jetty. The purpose was to create an experimental dredge spoil pad for marsh habitat creation. The area, successfully planted with marsh vegetation, has grown since its initiation. It is completely isolated from all other marshes, and, consequently, is not considered in this study. 2.4.4 R i v e r Mig ra t i on and Tra in ing As with dredging, the purpose of river training is to establish and maintain a navigable channel. The Fraser River shoals naturally as it approaches the Strait of Georgia and, left to themselves, the main channels shift frequently (Ladner, 1979; Johnston, 1921) (Figure 2.2). Training walls and jetties constrain the main channel throughout the delta, eliminating lateral migration and inducing scouring of the channel bed. Jetties have also effectively extended the river channel 11 km across the tidal flats, increasing the ability of the river to retain material in suspension and to transport sediment offshore (Milliman, 1980). 31 On the South Arm and the main channel downstream of New Westminister, river training structures are located in three areas: at the river mouth, in the Steveston - Ladner Bend area, and near New Westminister (Table 2.4 and Figure 2.5). Information in the following sections pertaining to river training structures and channel migration is compiled from three sources, Public Works Canada (1949), Public Works and Government Services (1994) and the charts discussed in Chapter 3 (see Figure 3.2), unless otherwise indicated. 2.4.4.1 River Mouth In 1860 the main entrance channel to the South Arm swung south across the tidal flats. At that time the development of a channel directly west of Steveston was evident, and by 1886 this channel carried the majority of the flow. In order to secure a deep water channel across the tidal flats, the Department of Public Works Canada has constructed numerous training features in this area (Figure 2.5). The first was a series of dams built between 1886 and 1904 on the tidal flats west of Reifel Island and the mouth of the South Arm. No.l Dam, located across the southern channel on the tidal flats, was most likely an attempt to restrict the amount of southward flow and to constrain the river to one channel, the same function performed at a later time by the South Steveston Jetties and the Albion Dykes. No.2 Dam appears to have been constructed along the southern side of the active channel, possibly required due to a shift in the channel as a result of No. 1 Dam. No. 3 Dam was built along the northern side of the channel with the intent of closing the entrance of Hayseed Slough, which flowed to the northwest. Later, a northward shift in the channel left No. 3 Dam in the middle of the shipping lane, where it remained as a submerged dam just south of the bend in the Steveston Jetty until it was removed (date of removal is unknown, but probably during the late 1920s). 32 Table 2.4: River training structures in the Fraser River delta (1886-1994). FRASER RIVER TRAINING STRUCTURES (numbers correspond with Figure 2.5) # Name Construction Date Purpose 1 No. 1 Dam 1886-1893 - prevent channel from flowing south across tidal flats, no longer exists. 2 No. 2 Dam 1888-1894 - prevent channel from flowing south across tidal flats, supersedes No. 1 Dam, no longer exists. 3 No. 3 Dam 1900-1904 -control north side of channel, closed Hayseed Slough, later removed as it was in shipping lane. 4 Ewens Slough Dam 1900? - closed slough across Westham Island. 5 Duck Is. Wing Dams 1910-1913? -unknown, probably to divert flow north to prevent erosion of Westham Island, obsolete. 6 Steveston North Jetty 1912-1932 -control north side of South Arm, improve navigation channel, extend channel across tidal flats. 7 North Arm Jetty 1914-1917 - control south side of North Arm, extend channel across tidal flats. 8 Woodward Training Wall 1922-1936 -control south side of channel, promote scouring, reduce dredging. 9 Woodward Dam 1925-1927 -close Woodward Slough channel, deflect flow into main channel. 10 Steveston Wing Dams 1925-1929 -3 dams, deflect flow towards main channel, increase channel scouring, increase accretion of Steveston Is. 11 Annieville Dyke 1927-1930 - constrict channel, promote scouring near Annacis Is., replaced 3 groins in this position (since 1900?). 12 Steveston South Jetty No. 1 1930-1932 - prevent drainage to south, promote scouring, too far south, obsolete. 13 Albion Dyke No. 1 1935-1936 - control channel, replace Steveston South Jetty No. 1, too far south, obsolete. 14 Sapperton V Dyke 1935 - divide flow between main (Port Mann) channel and Sapperton Channel, moved up stream in 1949, removed in 1994. 15 Albion Dyke No. 2 1936-1940 - replaced Albion Dyke No. 1, control channel, promote scouring. 16 Kirkland Is. Bifurcation 1949 - divide flow between South Arm and Ladner Reach. 17 Steveston South Jetty No.2 1954 - extension to Albion Dyke No. 2, to close drainage gaps to south of main channel. 18 Steveston Rock Dam 1954 - prevent Cannery Channel from silting up, partially removed in 1956 to allow channel flushing. 19 Sapperton Wing Dams 1955 - divert flow into main channel, protection for booming grounds. 20 Steveston Is. Shearboom 1960 - prevent floating debris from entering Cannery Channel, obsolete. 21 Trifurcation Wall Phase 1 1967 - promote local scouring, reduce dredging. 22 Trifurcation Wall Phase 2 1968-1969 - divide flow between South Arm, North Arm and Annacis Channel, reduce sedimentation of Annacis Channel and erosion of Annacis Island. 23 Trifurcation Wall Phase 3 1969-1970 - promote local scouring, reduce need for dredging. (data from Public Works Canada , 1994; 1957) 33 34 Strangely, none of these early attempts at river training are shown on the contemporary hydrographic charts, and the fate of these structures is unknown. If their purpose was to focus the river into the westward flowing channel, then they were successful. A series of jetties and dykes now controls the Fraser River across the tidal flats, with the intent of maintaining a navigable channel by promoting scouring. The first of these to be constructed, the Steveston North Jetty, was built in six stages between 1912 and 1932, and continues to function in the same location today. The southern side of the channel was initially controlled by the Steveston South Jetty No. 1, built in 1930-1932. The channel was further narrowed by the construction of the first Albion Dyke in 1935-1936. However, it was quickly realised that both these structures were too far south to be effective, and the Albion Dyke No. 2 was built immediately north of them in 1936-1940, rendering the Steveston South Jetty No.l and the Albion Dyke No. 1 obsolete. A later structure, the Steveston South Jetty No. 2 (1950-1952) superseded the downstream section of the Albion Dyke No.2, further constraining the channel. The second entrance to the South Arm is Canoe Pass, to the south of Westham Island. By 1899 a channel was charted across the tidal flats and marked by buoys. Although Canoe Pass, originally referred to as the South Channel, varied yearly in depth and navigability (Ladner, 1979), it was used by fishing boats, as was indicated by the canneries existed along its shores, until the middle of the 1900s. Today Canoe Pass is used primarily by small recreational boats. 2.4.4.2 Steveston and Ladner Bend The greatest changes in channel location in the delta have occurred in this region. In 1860 the main channel followed Sea Reach along the east coast of Westham Island and then hugged the south shore until reaching the present location of Ladner Marsh. At this point the 35 channel swung northward past Deas Island to continue upstream. Upstream of Deas Island there has been very little change in the channel location over the last 140 years. In 1860 the islands located today in the middle of Ladner Bend did not exist, (see Figure 3.2). Between 1880 and 1884 dredging occurred in Woodward Slough, suggesting that the main channel was starting to favour this middle route. However, comments in Ladner's memoirs (1979) suggest that the southern route continued to be the main deep water channel into the 1890s. By 1899, however, the main channel had shifted to the middle route through Woodward Slough and the island configuration had become similar to that of today. Between 1860 and 1899 Ladner Marsh, Deas Island and Tilbury Island all accumulated large quantities of sediment, as did the other islands in Ladner Bend. In 1899 Steveston Island did not exist. Over the next few decades a bar developed and by 1924 an island had begun to form. A series of wing dams was built in the vicinity of Steveston Island between 1925 and 1929 to deflect flow into the main channel, thereby enhancing scouring and reducing the need for dredging. Steveston Island was constructed from dredge spoils during the 1930s and was added to during the next decades (Watmough, 1972). By 1912 the shipping channel was well established in Woodward Slough. Three pile wing dams were built on the northwest end of Duck Island. The dates of construction and the original purpose of the wing dams are unknown, but they appear to have been built some time between 1910 and 1913. They were most likely designed to deflect flow north in order to lessen erosion on the eastern banks of Westham Island (Tarbotton, June, 1999 pers. com.). Later, sedimentation around the base of the pilings choked off the downstream end of Woodward Slough. In 1912 the northern channel, following the southern shore of Lulu Island, began to develop. This channel, once sufficiently deep, would be the most direct shipping route from 36 New Westminster to the river mouth. By 1918 shipping traffic was using the northern route, although the Woodward Slough channel was still open. As the northern channel widened, it eroded the southern portions of Gilmore Island and the northern side of the large shoal that eventually became Woodward Island. This shoal compensated by expanding southward, constricting Woodward Slough. In order to prevent the river from diverting south again through the Ladner Bend islands, a training wall (1922-1936) was constructed along the northern side of the large shoal, Woodward Island, and a dam (1925-1927) was built between Rose and Woodward Islands, closing off Woodward Slough. A potential return of the river to the southern route through Ladner Reach, following erosion of the upstream end of Kirkland Island, was prevented by the construction of the Kirkland Bifurcation in 1949. Designed to re-establish the 1919 location of the upstream tip of Kirkland Island, the Bifurcation controls flow division between Ladner Reach and the Main Channel. This combination of training structures effectively prevented the main channel from shifting, and continues to hold it in position today. Little change has occurred in the Ladner Bend area since the 1930s. 2.4.4.3 Tr i furcat ion and New Westminster In the area between Annacis Island and New Westminster there are two sets of river training structures. The oldest is on Sapperton Bar, the eastern section of the shoal known as City Bank. Between 1860 and 1899 City Bank accreted upstream. In 1935 a V-dyke was built at the upstream end of the Sapperton Bar in order to divide the flow between the main channel and Sapperton Channel. Eventually an island formed between the arms of the V, and the dyke was no longer necessary to split the flow. The dyke pilings were removed in 1994. The second set of river training works is the Trifurcation Wall at the northeastern end of Annacis Island. This large project, constructed between 1967 and 1970, was undertaken in order 37 to control the amount of flow entering the North and South Arms and Annacis Channel, and in order to promote local scouring. At present approximately 12 % of flow is carried by the North Arm (Northwest Hydraulic Consultants, 1999). The Trifurcation consists of a series of training walls along the southern shore of the South Arm and along the southern shore of Annacis Island, a V-wall at the upstream tip of Annacis Island and two rock weirs off New Westminster. 2.4.5 River Management Time Periods Four distinct periods of river management can be identified for the South Arm of the Fraser River: 1) Prior to 1880 - Prior to 1880 there was no river management in the lower Fraser River. Localised structures, such as fishing weirs and docks, would have had a negligible impact on overall sedimentation patterns. 2) 1880 to 1910 - In the years following 1880 snag removal, small scale dredging and construction of three small dams on the tidal flats occurred. The activity during this period was minor compared to that of following years. 3) 1910 to 1954 - During this time all major river training structures in the delta area were built and large scale dredging to deepen the shipping channel began. This was the most active period of river management. 4) 1954 to present - This period is one of maintenance. Little further river training occurred, with the exception of the construction of the Trifurcation Wall at Annacis Island, approximately 10 km upstream from the study area.. The main activity during this period was dredging to deepen the channel in order to accommodate increasingly large ships. The most intense period of dredging was between 1974 and 1994, when an average of 4.48 x 106 m3 of sediment was removed from the South Arm each year. 38 These distinct periods in the management of the Fraser River provide a framework , against which the sedimentary development of the marshes can be compared in order to assess the impact of human activity. 39 CHAPTER 3 MAPPING THE DELTA 3.1 Introduction The objective of this research is to determine the impact of human activity on the pattern of deposition within the Fraser River delta. Short of an intensive coring program to determine the subsurface nature of the whole delta, the only way to establish images of the delta surface morphology at various times in the past is through historical records. The period for which historical records of the Fraser River delta morphology exist is relatively short, commencing only in the early 1800s. These records include maps, written accounts, sketches and, post 1928, aerial photographs. Although many different types of maps exist of the delta area, hydrographic charts, those surveyed with the purpose of showing the river channels and banks, were chosen for this research. Maps created for other purposes, such as those delineating property boundaries, frequently overlook details concerning non-terrestrial areas, such as marshes. Hydrographic charts also provide the best coverage of the delta, from 1827 to present. However, it is not possible to use them for quantitative analysis, as will be explained in sections 3.2.2 and 3.3.1. Consequently, maps created from aerial photographs, as described in section 3.3.3, are used to determine changes in marsh area. 40 3.2 Hydrographic Charts 3.2.1 His tory of M a p p i n g the Fraser R ive r Delta The earliest charts of the Fraser River delta were produced by the British Admiralty. The first British Columbian navigation data obtained by the Admiralty were the charts and sailing directions compiled by Captain George Vancouver during his voyage of 1792-1794. Vancouver's collection included information from earlier voyages by Captain James Cook, Spanish explorers, and marine fur traders. However, these explorations noted only the presence of a river mouth, and failed to realise the size and potential importance of the Fraser River delta. The earliest chart of the river was produced in 1827. Unfortunately, the river configuration of the 1827 chart is so unlike that of later charts, that it is not useful as a baseline for comparing channel morphology over time (Figure 3.1). The first systematic surveying of the Fraser was done under Captain George Henry Richards between 1858 and 1859, resulting in the chart published in 1860, which was used as the base map for publications until the 1940s. The responsibility for surveying and for producing maritime charts shifted to the Canadian government after British Columbia entered Confederation in 1871. However, the British Admiralty agreed to continue surveying the B.C. coast when needed if the Canadian government bore half the cost. Admiralty surveys were conducted until 1910, when the last British Admiralty survey vessel in B.C. was decommissioned. The Admiralty, however, continued to publish charts of the British Columbian coast based on earlier surveys and new Canadian information until the mid 1950s. The Canadian Hydrographic Service produced its first chart of B.C. in 1909, and when the British Admiralty cancelled its B.C. charts in 1954, the files were transferred to the Canadian Hydrographic Service (Sandilands, 1970). 41 42 The Federal Public Works Department, or Public Works Canada (now the Department of Public Works and Government Services), assumed responsibility for Fraser River navigation channels in 1871, the year British Columbia entered Confederation. Unfortunately, records prior to 1898 were destroyed in a fire which razed much of the city of New Westminster in that year (Public Works Canada, 1949). Charts of the navigation channel have been produced since 1885, but are available only from 1898. Frequently more than one chart was produced per year due to the unpredictable shifting of sand bars during the freshet. 3.2.2 Reliability and Accuracy of Fraser River Charts There are a number of problems with historical maps and charts which limit their use for accurately determining changes in sediment patterns over time. Surveying techniques changed from manual depth sounding and surveying to the use of aerial photography, satellite imagery, and computerised soundings and surveying during the period covered by this report (1860-1994). Changes in chart production and publication technology, from manual drafting to computerised digitising, have also occurred during this time period. As a result of these advances, chart accuracy has also changed. Crowell et al. (1991) estimate that the error in locating control points for historical American topographic maps (scale of 1:10 000) is 2.5 to 5.0 m on a map dated 1860, and less than 1.5 m on one from 1969. While these values cannot be applied to the hydrographic charts of the Fraser River, they do provide some insight into the variation that can be expected between charts of different ages. A reference system or control points must be present on all charts, in order to accurately compare charts of different ages Changes in surveying standards over time may further complicate comparison of charts of different ages. For example, recent charts tend to include more detailed information about shoals and other bottom features than older charts, because of the greater draft requirements of 43 modern ships. In addition to changes to surveying techniques over time, surveying standards change between organisations. The Fraser River charts considered in this chapter were surveyed by four different organisations, the Hudson's Bay Company for the British Admiralty (1827 chart), the British Admiralty, the Canadian Hydrographic Service, and Public Works Canada, and consequently may reflect different surveying standards. The policy of the British Admiralty, for example, is to always record the minimum depth measured, which results in a tendency to exaggerate the volume of sediment present (Carr, 1980). On the other hand, the size of sediment bodies surveyed at high water may be underestimated when water depths are corrected to a common reference plane, such as low low water. This is not a problem if areas under water during surveying, but exposed at low low water, are accounted for. Changes in scale, as well as in datum, may also greatly alter the apparent changes in sediment areas between different charts (Carr, 1980). Consequently, the differences between the various scales and planes of reference used in the charts of the Fraser River (Table 3.1) must be rectified before detailed and accurate comparisons can be made. Unfortunately, information about the planes of reference are missing from the earlier charts. Detailed information regarding the time period over which the surveying was done and the way in which the survey data were modified to a uniform datum level also is vital for accurately interpreting hydrographic charts of the Fraser River because water levels fluctuate both daily and seasonally. Since surveys took place over the duration of several tidal cycles, measurements taken at different tidal stages would have to be altered to a uniform water level. For example, surveyors of the 1827 chart spent nine days charting the channel across the tidal flats (Sandiland, 1970), while information on the 1860 chart suggests that surveying was done over a two month period. Seasonal variation in river level would also have to be accounted for. 44 Table 3.1: Hydrographic charts used in this research. Date Publisher and chart # Chart Scale Projection Datum 1827 survey by Hudson Bay Company British Admiralty Chart #1922 1:72960 (not accurate) not provided not provided 1860 British Admiralty Chart #1922 1:72960 (not accurate) not provided not provided soundings: March - April 1874 corrections on 1860 survey British Admiralty 1:72960 (not accurate) not provided not provided soundings: March - April 1899 corrections on 1860 survey British Admiralty Chart #1922 1:72960 (not accurate) not provided not provided soundings: March - April 1915 survey by Canada corrections on 1860 chart British Admiralty Chart #1922 1:71510 not provided mean low low water (52.43 ft below bench mark on New Westminster post office) or 8.47 ft below mean tide at Sand Heads 1932 survey by Canada corrections on 1860 chart British Admiralty Chart #1922 1:72900 not provided reduced approximately to mean low low water (52.43 feet below bench mark on New Westminster post office) 1946 survey by Canada corrections on 1860 chart British Admiralty Chart #1922 1:72000 gnonomic mean low low water (52.43 feet below bench mark on New Westminster post office) Another problem encountered in historical charts of the Fraser River is that of revised, or corrected, charts. Only a few complete surveys of the river have been done, such as those for the 1827 and 1860 charts. The majority of charts are the result of localised survey data being added to printing plates containing information from earlier surveys. Information describing which sections have been revised is contained in Notices to Mariners, published by the Canadian Coast Guard since 1859 (Sandilands, 1970). Furthermore, since the middle of the 1900s charts have been showing less and less detail of areas away from the navigation channel. Hydrographic charts of the Fraser River produced during the last few decades show no detail of side channels, banks and marsh areas. 45 Even if these technical problems associated with historical hydrographic charts are overcome, there is a problem with interpretation of geomorphic features. Early maps, surveyed on the ground, often relied on several individuals providing their interpretation of what they saw. In the case of marshes in a tidal environment, this problem becomes paramount. The difficulty of distinguishing between terrestrial, marsh and marine environments is compounded by the tidal stage at the time of observation. Areas in the Fraser delta which appear to be dry land covered with herbaceous plants and small shrubs at low tide, may in fact be inundated at high tide. Intertidal areas of the Fraser delta have been labelled as either marsh, land or sand bar on consecutive charts, suggesting that variations in interpretation are indeed a problem. 3.3 Mapping Historical Marshes of the Fraser River delta The creation of a series of maps to show the development of the delta and the marshes has taken three distinct steps. Initially, small scale British Admiralty and Canadian hydrographic charts showing the whole delta area were used to produce images of general delta development. Next, as a result of problems discovered in the first step, large scale Public Works Canada hydrographic charts showing just the study area were used. Finally, aerial photographs were employed. In this section, the steps involved and the problems encountered will be outlined. Charts were digitised using Roots® digitising program. Changes in marsh area were determined using Arclnfo®, a program which also allows for correction of chart distortion. 3.3.1 British Admiralty and Canadian Hydrographic Charts Small scale British Admiralty and Canadian hydrographic charts were chosen to create a sequence of maps showing the development of the delta and the marshes because they provided the longest record, from 1860 to present. However, the lack of stable features in early charts 46 limited the control points to bedrock points to the north of the delta and to Fort Langley, to the east of the delta. These control points were not sufficient to establish a uniform reference grid or to overcome chart distortion. Once the charts were digitised and computer correction was attempted, it became apparent that the charts prior to 1915 have discontinuities resulting from inconsistent surveying technique. In addition to this, land masses were not accurately surveyed and the charts portray erroneous areas and shapes, which is evident in later charts when compared to aerial photographs from the same period. There also tends to be a lack of information about the extent of the marshes along the front of the delta. Consequently, the small scale hydrographic charts are useful only for providing an overall impression of changing channel morphology between 1860 and 1991 (Figure 3.2). 3.3.2 Public Works Canada Charts Large scale charts produced by Public Works Canada were considered as a source to determine marsh areal change. While these provide reasonably good coverage, 1898 to present, they too are fraught with problems. The earlier maps provide good detail of marshes, islands and the delta front, but the problem of surveyor interpretation of marsh boundaries exists, as it does in the small scale hydrographic charts. On later charts, detail of features peripheral to the navigation channel is greatly reduced. Eventually, no information regarding marsh boundaries is provided. In addition, there is a complete lack of a uniform reference system and no control points with which to create one. Finally, the 1965 chart is completely missing an island in Ladner Reach which can be seen in 1964 and 1974 aerial photographs. Such omissions reduce confidence in the accuracy of the charts. For these reasons, the Public Works Canada charts were not used. 47 3.3.3 Aerial Photographs The first aerial photographs of the Fraser River delta were taken directly along the river in 1928. Two years later the whole delta was photographed. Creating maps of marsh areas from aerial photographs has several advantages. Primarily, there is no intermediary, such as a surveyor or cartographer, whose criteria for identifying marshes would be unknown. Secondly, the first aerial photographs were taken after the delta had been developed with roads, providing numerous, easily identifiable control points from which to create a reference grid. There are three main problems with aerial photographs. One is the increasing distortion towards the edges of the photographs, avoided by using only the central portion of each photo. Distortion due to changes in land elevation is not a problem in a flat delta. The second problem involves the timing of the photography flight. Flights at different tidal stages can provide divergent impressions of marsh area. Fortunately, most of the flights cross the delta at reasonably low tide. In the one year (1954) when the lowest edge of the marsh was submerged, the marsh vegetation under water shows up distinctly darker than the adjacent sand flats, making it possible to identify the marsh boundaries. Marsh boundaries were identified as the outer limit of vegetation, excluding eel grass (Zostera marina). Familiarity with the appearance of marsh vegetation on aerial photographs, obtained during field work using photos, aided accurate interpretation of earlier photographs. Areas with trees were considered land, as were any dyked areas without clear access to tidal waters. Photographs from 1930, 1954, 1974 and 1994 were scanned with a Canon Imagerunner 550, and fitted together to create a composite with sufficient control points (Figure 3.3). The control points used are listed in Appendix 1. The photo mosaics were then digitised using Roots. To ensure the accuracy of the resulting maps, they were fit to a 1991 controlled digital map of the delta provided by FREMP (Fraser River Estuary Management Program). 49 Figure 3.3: 1994 aerial mosaic of the study area. 50 The area of Brunswick Point was missed during the 1930 aerial photography. An aerial photograph from 1932 was used to fill in the gap in the 1930 composite. All photographs used are listed in the reference section. 3.4 Results The attempts to map the changes in the surface morphology of the Fraser River delta produced three results. The first, a series of maps between 1860 and 1991, have been compiled to show the general changes in river morphology (Figure 3.2). Secondly, a detailed account of marsh development between 1930 and 1994 was created from aerial photographs (Figure 3.4). Finally, based on the aerial photographs, changes in marsh area were calculated using Arclnfo® (Table 3.2). 3.4.1 Changes to Channel Morphology Figure 3.2 shows the changes in the deltaic reaches of the Fraser River between 1860 and 1991. General areas of sediment gain are shown for the periods 1860 to 1899 and 1899 to 1946. When considering these maps, one must remember that they reflect only what was presented on historical charts and may not be accurate for the reasons mentioned earlier. A detailed discussion of channel change is presented in section 2.4.4., along with the implementation of river management. The most striking change is the apparent influx of sediment into the delta between 1860 and 1899. Many side channels and backwaters filled in during this period. The most notable area of sediment gain occurred in the islands opposite Ladner. In 1860 the main channel flowed along the south bank of the river at Ladner. At this time there was a cluster of islands close to the northern bank. By 1899 the main channel had shifted to a more central route and islands had 51 formed in the former main channel. The appearance of these islands was relatively rapid, as indicated by this comment by Ellis Ladner: "In the latter part of the 1890s, the S.S.Yosemite could make a complete swing opposite the warf [at Port Guichon, immediately downstream from Ladner]. In the channel opposite Port Guichon, within the next 15 years, a sand bar formed and was submerged only by higher tides. By 1940 the area was a long, low island with willows growing on it." (Ladner, 1979). During this period of rapid sedimentation in the delta, two large floods occurred, one in 1882 and the second, the largest flood recorded on the river, in 1894. These events would have carried a lot of sediment into the delta area, which otherwise may not have reached the delta over such a short time period. Other periods of high flow, such as 1912 to 1925, and 1948 to 1977, have occurred without such a large influx of sediment. Relatively low dredging activity during the majority of the high flow periods suggests that there was no uncommonly large increase in sediment load. Consequently, it is possible that the unusually large volumes of sediment reaching the delta during the late 19th century are the result of specific activities. During this period the Fraser River gold rush was taking place in the Fraser Canyon and areas further up river (see section 7.3.1 for details on the gold rush). Mining, particularly hydraulic mining, washed huge volumes of material into the river. This was also the period when much of the area'adjacent to the river banks was cleared for the first time, also presumably increasing the sediment load of the river. 3.4.2 Marsh Development Figure 3.4 shows the development of the marshes in and adjacent to the study area between 1930 and 1994. In general there has been an increase in marsh area, as is demonstrated in Table 3.2. Figure 3.5 delineates the regions used to calculate marsh area in Table 3.2. 52 Table 3.2: Changes in marsh area between 1930 and 1994 based on aerial photographs. Marsh area (m x 10 ) 1 Marsh area loss/gain (%) 1930 1954 1974 1994 1930-1954 1954-1974 1974-1994 1930-1994 Lulu Island 3620 4750 4720 5910 31 -1 25 63 Fronting Wesfham-Reifel Is. 2440 4500 5620 7280 84 25 30 198 Brunswich Pt. 800 770 1690 1780 -4 119 5 123 Ladner Bend Islands 3490 4060 4210 4500 16 4 7 29 Reifel Island 1030 0 0 0 -100 - - -100 Banks 2640 2170 1320 1250 -18 -39 -5 -53 Total Marsh 14020 16250 17560 20720 16 8 18 48 Total Marsh without Reifel Island and Banks 10350 14080 16240 19470 26 15 20 88 Figure 3.5: Regions of marsh growth. Losses to marsh area occurred primarily as a result of land reclamation. The reclamation of the majority of Ladner Marsh is the primary cause of the high loss (- 50 %) in marsh area along the river banks between 1930 and 1974. Smaller, natural losses have occurred due to channel migration (such as along the north side of Woodward Island) and the succession to treed 54 terrestrial areas (such as on Duck and Barber Islands). Marsh growth shown on this map is preceded by development of sand bars (sandy) and tidal flats (muddy). These features were omitted to avoid further complicating the diagram. Steveston Island, or Shady Island as it is also known, is included as land throughout the maps since it is primarily constructed and has only a negligible area of marsh along its north side. Between 1930 and 1954 major changes happened in the marshes fronting Westham and Reifel Islands. Rapid marsh growth occurred in the lee of Steveston South Jetty No.l, built in 1930-32. The patchy nature of the 1930 marsh along southern Westham Island was filled in by 1954. Marshes of the Ladner Bend Islands experienced their largest period of growth (16 %) during this time, due to the construction of river training structures in this area. The largest change is the development of Woodward Island. New marsh formed on the sand bars, which had formed in the old channel after Woodward Slough was closed off by Woodward Dam (1925-27). The largest loss of marsh between 1930 and 1954 occurred when the eastern half of Ladner Marsh was reclaimed for cultivation. Much of Reifel Island, although dyked prior to 1930, was also cultivated during this period, as was the upstream end of Barber Island. The apparent loss of 4 % of marsh area off Brunswick Point is most likely due to error associated with patching the 1930 composite with the 1932 aerial photograph. During this period, 1930 to 1954, there was a total increase in marsh area of 16 %, the majority of it off Westham and Reifel Islands due to the construction of jetties in the area. The second largest flood recorded on the Fraser River, 1948, occurred during this period, and would have been instrumental in transporting sediment into the delta. However, given that the majority of this period, 1930 to 1948, was one of low flows, training structures and not river regime must be responsible for much of this growth in marshes. 55 Between 1954 and 1974, a period of high river flows, further growth occurred in the marshes fronting Reifel Island following the construction of the Steveston South Jetty No.2 in 1954. It is unfortunate that no aerial photographs exist prior to the construction of the Steveston North Jetty, begun in 1912 . Given the rapid growth of marshes in the lee of the South Jetties, it is likely that rapid growth also followed the construction of the North Jetty. The extent of the growth in the lee of the Steveston South Jetties and Albion Dykes is greater than that in the lee of the Steveston North Jetty. This is because the Steveston South Jetties and Albion Dykes consist of pilings, and are pervious, allowing a greater quantity of sediment to pass through than the solid Steveston North Jetty. The marshes to the south of the main channel have a sandier, firmer substrate than those to the north, indicating that coarser sediment passes through the Steveston South Jetties and Albion Dykes. Due to deterioration of these structures, the amount of water flowing through them is increasing: at present, approximately 27 % of the flow in the main channel escapes through Albion Dyke No. 2 (Northwest Hydraulic Consultants, 1999). Another area of rapid marsh growth, 119%, between 1954 and 1974 is situated off Brunswick Point, vegetating an area that was sand flats in the 1930s. This growth is possibly in response to a decrease in flow through Canoe Pass following the Kirkland Bifurcation (1949), which directed flow away from Ladner Reach. Flow must have also been impeded by the development of two small islands off Ladner. Growth of these islands was greatly assisted by the dumping of dredge spoils, which can be seen as land in the middle of each island. Dredge spoils were also dumped on the southern tip of Ladner Marsh. Adjacent to this more marsh was lost in Ladner Marsh due to the construction of a sewage lagoon in 1963. These losses, in addition to the loss of Deas Island marshes, account for much of the negative growth (-39 %) in marsh area along the banks of the Fraser River between 1954 and 1974. Further marsh area off Reifel and Westham Islands was reclaimed during this period, as was Garry Point at Steveston. 56 The loss of Garry Point is responsible for the negative marsh growth, -1 %, off Lulu Island. In all other areas off Lulu Island the outer edge of the marsh advanced seaward between 1954 and 1974. The biggest expansions in marsh area between 1974 and 1994 are adjacent to the channel mouths in the lee of the jetties in front of both Lulu Island, and Westham and Reifel Islands. The marshes off the north end of Lulu Island also experienced rapid growth. One possible factor in this growth is the large scale dredging which occurred during this period, increasing the amount of sediment in suspension, and therefore available for marsh development. Further loss (-5 %) of marsh area to land reclamation occurred along the banks of the river. As in the period between 1930 and 1954, marsh area increased greatly during a period of low river flow. If the areas with large losses due to land reclamation are removed, Reifel Island and the Banks, the resulting marsh gains are 26 % (155.4 x 103 m2/a) in 1930-1954,15 % (108.0 x 103 m2/a) in 1954-1974, and 20 % (161.5 x 103m2/a) in 1974-1994. These results suggest that river regime, characterised by high flow during 1954 to 1974 and mainly low during the other periods, is not the controlling factor in determining the rate of lateral marsh growth. Marsh growth during 1930 to 1954 occurred immediately following the construction of the river training structures in the area, and dredging activity was at its peak between 1974 and 1994. Dredging, by increasing the amount of sediment in suspension, may be a significant factor in marsh growth. It is also interesting to note that lateral expansion of the marshes was taking place during rising relative sea level, which is normally associated with reduced rates of marsh seaward growth. Relative sea level rise between 1930 and 1994 is estimated to be 237 mm, based on the figures provided in section 2.2.2. The actual relative sea level rise may be somewhat lower, due to slower rates of eustatic sea level change in the early part of the century. 57 Small patches of marsh are now forming off the front of Westham Island (Figure 3.4). These are likely indicators of future areas of marsh development. It appears that the marshes along the front of the Fraser River delta naturally have a very irregular shape and grow laterally by colonising small patches, which later become the leading edge of the marsh as the areas in between become vegetated. This chapter has dealt with the areal extent of marsh development, rather than vertical marsh growth. Information about the vertical growth of the marshes has to be derived from cores, and is the subject of the following chapters. 58 CHAPTER 4 SEDIMENT SAMPLING AND ANALYSIS 4.1 Introduction The purpose of this study, to identify the impact of human activity on the marshes of the Fraser River delta, requires that a sedimentological history of the marshes be developed. In order to achieve this end, a set of sediment cores was collected, allowing comparison between the sedimentary record and the known historical record of human activity. In this chapter, selection of core sites and core collection will be discussed, followed by core analysis and results. 4.2 Site Selection and Description The selection of specific sites within the delta for data collection was possibly the most important step in ensuring the success of this project. Sites for sampling were carefully selected based on a series of requirements, which are: 1) a continuous depositional environment over the period of interest (1800 to present), undisturbed facies and clear depositional layers; 2) sedimentation must have been affected by human activity (such as training walls and dredging); and 3) must be easily accessible by boat or from land. Additional sites, which have been less directly impacted by human activity, are desirable for comparison purposes, although no Fraser River marsh is truly unaffected by large scale human activity. The only marshes not influenced 59 by large scale human activity are those pre-dating the late 1800s. Consequently, subsurface evidence dating from this time will be used to provide a natural control, where possible. Hydrographic charts and air photographs, dating back to 1860 and 1930 respectively, were consulted in order to select the least disturbed sites, since cores with minimal erosion are required to ensure a complete historical record. Due to the size of the Fraser delta, it was decided to focus solely on the Main or South Arm of the river. This channel contains the largest volume of maritime traffic and, consequently, is the focus of most dredging and river training activity. Using the requirements listed above, four areas were identified as potential core sites. These are immediately north of the Steveston North Jetty, immediately south of the Steveston South Jetty, and in the islands of the Ladner Bend area which are affected by the Woodward Training Wall and Dam and by the focusing of the main channel to the northern route. The fourth area selected is along the front of Westham Island at the mouth of Canoe Pass. This area is least likely to have been affected by training structures or dredging as Canoe Pass is a subsidiary channel, and as such has been relatively unaltered, except for a change in flow resulting from the diversion of the main channel from Ladner Reach to more northerly routes. In this study, the core sites in the marshes fronting Westham and Lulu Islands are referred to collectively as those from the front, while core sites on the smaller islands, Woodward, Barber and Duck, adjacent to the main channel, are referred to as the island sites. Within these areas, specific core sites were selected in the field on the basis of apparent length of record, determined where possible from lamination sequences visible in channel banks, maintaining a good spatial distribution of sites, and accessibility. South of the Steveston South Jetty, the area occupied by the George C. Reifel Bird Sanctuary had to be avoided, reducing the marsh available for coring. Permission to core all the other areas was obtained through F.R.E.M.P. (Fraser River Estuary Management Programme). 60 4.3 Core Col lect ion and Hand l ing A reconnaissance field season was completed during the summer of 1995. Nineteen cores were collected using a percussion method involving a sledge hammer and PVC tubing (7.62 cm internal diameter, 1.5 m length) (Figure 4.1). The average barrel penetration depth was 1.2 m, however, due to compaction of the sediments, the average core length in the ground was 0.96 m. Loss of material during core recovery further shortened the cores, with a resulting average core length of 0.73 m. Two cores were lost. Preliminary examination of the cores determined that longer records were required to access depositional environments pre-dating large scale human activity. Figure 4.1: Location of core sites in the Fraser River delta. 61 In order to penetrate deeper into the marsh sediments, a vibrocorer was used during a second field season. The vibrocorer, which works on the principle of liquifaction rather than mechanical force to drive the core barrel into the sediment, functions best in saturated sands and silts (Smith, 1984). Liquifaction of the sediments, resulting from the vibrations produced by the corer, occurs immediately adjacent to the core barrel, affecting less than a third of a centimetre of sediment on the inside and outside of the barrel (personal observations). Smith (1987) demonstrated that using a 7.5 cm internal diameter core barrel, as opposed to a smaller one, increased the penetration speed, reducing the compaction of the sediments. Sixteen cores were collected during the summer of 1996 using a portable vibrocoring rig and 7.5 cm internal diameter aluminum barrels (Figure 4.1). Barrel penetration depth ranged from 1.13m to 3.18 m, limited either by the length of the barrel or by channel and tidal flat sands beneath the marsh deposits. The resulting cores were 0.98 m to 2.54 m in length, showing compaction rates ranging from 13% to 62% (Table 4.1). Core depths mentioned in this report are not corrected for compaction, unless otherwise stated. The cores are labelled with the name of the island from which they were removed and a number (e.g. Lulu 33). Core sites were located using air photographs from 1986 (scale of 1:12,100). The numerous small channels which drain the marshes are visible on the photos, making this method very accurate. Where necessary, a GPS receiver was also used, as was triangulation from objects on dry land. One problem was determining the height of the marsh surfaces above a datum, in order to compare the cores. Due to the difficulty of establishing a known datum to which all the core sites could be compared in an area with highly variable water levels, it was decided to use substrate and marsh vegetation as a surrogate. The pattern of vegetation zonation in the Fraser River marshes is determined primarily by elevation, and thus inundation, with factors such as salinity and sediment texture being of secondary importance (Hutchinson, 1982). 62 Table 4.1. Core data. Core Name Barrel Penetration Depth (m) In-ground core length (m) Compaction % Final core length (m) Recovery % Duck 20 2.86 1.80 37 1.98 92.8 Woodward 21 2.87 2.09 27 2.51 97.6 Woodward 22 2.48 1.71 31 1.94 100 Duck 23 2.70 1.38 49 1.14 100 Reifel 24 1.40 1.20 14 1.17 95.0 Reifel25 1.71 1.27 26 1.23 97.2 Woodward 26 1.13 0.98 13 0.38 38.8 Barber 27 2.75 2.02 27 2.36 100 Barber 28 3.18 1.59 50 1.59 99.4 Westham 29 3.00 1.70 43 1.61 94.7 Westham 30 3.03 1.87 38 1.60 96.3 Duck 31 3.02 1.85 39 1.83 97.8 Woodward 32 2.74 1.04 62 0.91 100 Lulu 33 2.98 2.54 15 2.40 100 Lulu 34 2.83 1.60 43 1.52 99.4 Canoe Pass 35 1.91 1.64 14 1.15 100 Note: Final core length may include some stretching during core extrusion. Core compaction is the in-ground compaction resulting from the vibrocoring technique. Recovery % is the percentage of core successfully removed from the ground. Consequently, core sites may be grouped by vegetation or marsh zone, establishing a surrogate for elevation. O f course, having similar vegetation patterns today does not indicate similarity in the past. In this case, the depositional record is used to determine the environment of the period in question. The surface environments of the cores are summarised in Table 4.2. Typical marsh environments are shown in Figure 4.2. Once on dry land, the cores were extruded from the aluminum barrels onto a barrel of pre-cut (in half lengthwise) P V C tubing. The P V C barrels were then closed using the other half barrel and secured with copious amounts of duct tape. The P V C barrels were cut to the length of the cores and capped to ensure no leakage and no movement within the barrel. After the cores were analysed for environmental magnetic susceptibility (see section 4.5), which required whole cores, the cores were sliced open lengthwise using a blade sharp enough to cut through the marsh vegetation, and cleaned of any smearing resulting from the cutting. Ha l f the core was securely wrapped in plastic and stored, while the remaining half was photographed and logged before being sampled for further analysis (see Appendix 2). When not in use, the cores were stored in a 63 dark, cool basement, as no available refrigeration unit was large enough to accommodate them. A stylised representation of the core logs is shown in Figures 4.3 and 4.4. The purpose of these diagrams is to illustrate the sedimentary records of the cores, highlighting the areas of continuous visible laminations, which typically consist of clayey-silt and silty-sand alternating layers. In some cores, portions of the laminated record have been naturally disturbed to a point where laminations are no longer clearly detectable. These are labelled as distorted in the diagram. Table 4.2: Marsh environments characterised by substrate and vegetation cover. Environment (elevation)* Substrate Typical Vegetation Cover Core Sites** High Marsh > 415 cm Solid to stand on, High clay and silt content. Thick cover, variety of plants, typically: Potentilla anerina ssp. pacifica (silverweed), Typha latifolia (cattail), Agrostis exarata (spike bentgrass), Car ex lyngbyei, Lyngby's sedge Distichlis spicata spp. spicata (seashore saltgrass) Barber 27 Barber 28 Duck 20 Duck 23 Duck 31 Woodward 22 Middle Marsh 365-415 cm Soft to stand on, Puddles of water, Hummocks on the delta front, High clay and silt content. Thick cover, monoculture, typically: Scirpus maritimus (seacoast bulrush), Scirpus validus (soft-stemmed bulrush) Car ex lyngbyei, (Lyngby's sedge) Triglochin maritimum (sea arrow-grass) Woodward 26 Woodward 32 Woodward 21 Canoe Pass 35 Westham 29 Westham 30 Low Marsh 280-365 cm Sinking to soft to stand on, Standing water, Increasing sand content at lower levels. Cover sparser, substrate visible, typically: Scirpus americanus (american bulrush), Scirpus validus (soft-stemmed bulrush) Lulu 33 Lulu 34 Reifel 24 Reifel 25 (lowest edge of low marsh) Tidal Flats < 280 cm Solid to soft to stand on, Sandier. Low cover, sparser, typically: Ruppia maritima (ditch-grass), Zostera marina (common eel-grass) * Environmental divisions are based on personal observations and those of Hutchinson (1982). The elevation is given as centimeters above the local tide datum (300 cm below geodetic at Sandheads) **Core sites are listed in order of elevation, with Barber 27 being the highest and Reifel 25, the lowest, (based on data from Hutchinson, 1982; vegetation named according to Pojar and MacKinnon, 1994). 64 Middle marsh along a marsh creek, Woodward Island Figure 4.2: Typical marsh environments in the Fraser River delta. 65 66 67 4.4 Sediment Core Analysis The purpose of collecting sediment cores from the marshes of the Fraser River delta is to provide a sedimentary history showing the impact of river training and dredging. In order to do this, three steps must be completed: 1) the cores must be correlated, enabling comparison between cores; 2) the sedimentary history of each core must be established; and 3) the cores must be dated in such a way as to enable comparison with river training and dredging history. Environmental magnetism was used to correlate the cores. Sediment analysis included bulk density, organic content, grain size distribution and chemical analysis. Cores were x-rayed to expose laminations not otherwise visible. All sixteen cores were analysed for environmental magnetism and bulk density, however due to intense time and labour requirements, the other procedures were carried out only on those cores most likely to provide good results. The seven longest cores with the clearest, most continuously laminated sequences were chosen, on the basis that a laminated sequence indicates an undisturbed depositional history. These cores are Barber 27, Duck 20 and 31, Woodward 21, Lulu 33, and Westham 29 and 30. The methods used to correlate the cores and develop a sedimentary history will be presented in this chapter, along with the relevant results. Dating the cores will be discussed in Chapter 5. 4.4.1 Environmental Magnetic Susceptibility Whole cores were transported to the palaeomagnetics laboratory at the Pacific Geoscience Centre of the Geological Survey of Canada to be analysed for environmental magnetic susceptibility using a Sapphire Instruments susceptibility meter. In order to determine the range over which the sample's magnetic field would affect the sensor, a rock plug was passed through the scanner. It was found that the sensor detected the sample's magnetic field over a 5 cm range. Consequently, the cores were analysed at 5 cm intervals to eliminate overlap, and the 68 top and bottom readings of less than 5 cm from the core ends were discarded. The results are presented in Figure 4.5. Susceptibility meter results assume a constant core density. However, due to the varying characteristics of the core sediments, a constant core density is highly unlikely. In order to rectify this problem, the results are corrected using the average density of each segment analysed. Correlation of the cores based on environmental magnetism is presented in Figures 5.9 and 5.10, with the dating results from Chapter 5. Data are in Appendix 3. 4.4.2 X-ray Analysis Once the procedures requiring whole cores were complete, the cores were split into two half barrels, logged and subsampled. Sections for x-ray analysis were cut from the flat face of a half barrel of each of Barber 27, Duck 31, Woodward 21, Lulu 33, and Westham 29 and 30. These cores were selected for their laminated sequences. Westham 15, a core from the first field season, was also selected because it had been tested for 1 3 7Cs along with Duck 31. It was hoped that x-ray analysis would help to determine whether or not annual couplets existed. The resulting slabs, 0.8 x 4 x 26 cm, were analysed at the UBC Hospital Radiology Department using the medical mammography machine (technical specifications: Senograph 600T, aluminum target, setting at 27 kV and 25 mA current and recorded on Kodak Min-R film). Results of x-ray analysis are used in Chapter 5 (see cumulative couplets in Figures 5.6 to 5.9). 69 4 . 4 . 3 S e d i m e n t A n a l y s i s Four techniques were applied to analyse the core sediments. Bulk density was determined in order to correct the environmental magnetism. Organic content provides a measure of the marsh environment at the time of deposition. Grain size is also an indicator of depositional environment, and the fourth technique, chemical analysis for heavy metals, can be used as a dating technique. Results are listed in Appendices 4 and 5. 4 .4 .3 .1 B u l k D e n s i t y All sixteen cores were analysed for bulk density. The seven cores selected for detailed analysis were sliced into 1 cm sections, which were then cut with a "cookie cutter" of a known volume (16 cm3) to remove the layer disturbed by contact with the barrel and gently disaggregated using a mortar and rubber pestle. The 1 cm interval was selected as it provided a sufficient quantity of sediment for use in all other procedures, and yet it was small enough to reflect any subtle changes. The other cores were sampled at 5 cm intervals to replicate the intervals used for environmental magnetic analysis. Samples, approximately 1550, were dried at 105 C for 24 hours to remove hygroscopic moisture. Bulk density was determined as dry weight per sample volume or g/cm3 and used to correct the environmental magnetism. 4 . 4 . 3 . 2 O r g a n i c C o n t e n t Organic content of the sediments was determined using a loss on ignition approach (LOI), which involves burning the samples in a muffle furnace. The temperature at which sediment is burnt and the duration of the burn vary widely between studies (e.g. Evans, 1997; Arnaud, 1997; Bricker - Urso et al., 1989). A search of marsh literature indicated that the most commonly used procedure is to burn for 4 hours at 450 C, the temperature above which clays are 71 affected (DeLaune et al., 1989, Bricker - Urso et al., 1989). To ensure that this LOI method removed all organic material, a test was performed on identical subsamples which were either burnt, burnt and then treated with hydrogen peroxide, or treated with only hydrogen peroxide. The results indicated that burning at 450 C for 4 hours was sufficient to remove all the organic material. Large pieces of organic matter were removed and weighed prior to burning. Subsamples (3-4 g) of the seven cores selected for LOI analysis were taken from the 1 cm interval samples dried at 105 C. The results, expressed as organic content percent of the dry weight, show a decrease in organic matter down core. The highest organic concentrations are in the marsh layer at the surface (Figure 4.6). Due to natural decomposition, the lack of organic matter at depth does not necessarily indicate lack of a marsh environment. A combination of sediment texture and organic content is a more successful indicator of past marsh environments. 4.4.3.3 Grain Size Grain size analysis was undertaken to determine sediment texture using a combination of sieves and a Micromeritics SediGraph 5100 system. The grain size of the inorganic component of the sediment was determined at 2 cm intervals for all seven cores (Figures 4.7 and 4.8). Samples of 3 - 6 g were made by combining adjacent samples from the LOI procedure. Test runs were conducted on samples which had been either burnt, burnt and treated with hydrogen peroxide, or treated solely with hydrogen peroxide, demonstrating that the LOI procedure did not alter the sedigraph results. Samples were passed dry through sieves with openings of 250um, 180pm and 125um in order to determine medium (>250um), and fine (125-250um) sand. The very fine sand (63-125 um), silt (4-63 um) and clay (<4 um) fractions were determined using the SediGraph machine. The 180 um sieve was added, because sand of less than 177 urn is transported as wash load, not bed material load, in the Fraser River (McLean et al., 1999). 72 73 75 4.4.3.4 Chemistry The cores were analysed for heavy metal1 content for two reasons: 1) to see if the signature of human pollution is visible in the Fraser River delta sediments as it is in those of the lakes and marine environments in the region (e.g. the Strait of Georgia, MacDonald et al., 1991; Bumaby Lake, MacCallum, 1995); and 2) if the signature is distinguishable, to use it as a dating tool (see Chapter 5). A portion (2-3 g) of sediments, dried at 105 C and sieved to less than 63 um, was analysed for a suite of elements using a nitric-aqua-regia leach and ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Mercury was analysed by cold vapour atomic absorption. Sample intervals were variable, increasing down core to reflect increasing sedimentation rates. Chemical analysis was done at Chemex Labs in North Vancouver. Results, shown in Figures 4.9 to 4.12, present only the seven most interesting of the thirty-two elements analysed. Aluminum is of interest as it is remobilized from the soil during land clearance practices, such as forestry, as a result of increased organic carbon mobility (Schreier et al., 1997). Likewise, storm events can also increase aluminum concentrations in surface waters. Land clearance and storms have a similar impact on iron (Schreier et al., 1997). Zinc is generally increasing everywhere in the environment and is a good indicator of human activity (Schreier, Dec. 1997 pers. com.). Zinc was routinely used by the pulp and paper industry and is a common element in urban runoff (Macdonald, 1991). Wood and coal combustion are major sources of atmospheric zinc (Pott and Turpin, 1996). Copper is naturally very high in the sediments of the region, in addition to being a common element in urban runoff and sewage, due, for example, to copper pipes. Human-induced lead contamination in the environment is generally attributed to the use of leaded gasoline, which was introduced in the early 1920s ' The term, heavy metal, in this study refers to the nitric-aqua-regia leach, and consequently includes aluminum. 76 (Macdonald, 1991). In Canada, environmental lead concentrations have generally been decreasing since the introduction of unleaded gasoline in 1972. By 1990 unleaded gasoline was mandatory (Pott and Turpin, 1996). Lead in gasoline was replaced by manganese, making this element of interest since its occurrence has consequently increased in the environment. Mercury is another good indicator of urban pollution. It is not exactly known why, although batteries probably constitute a major mercury source (Schreier, Dec. 1997 pers. com.). Mercury, which is very volatile and tends to move with organic matter, is also released from the soil during burning and flooding (Schreier, Dec. 1997 pers. com.). In the Fraser River marshes, mercury may also be associated with sediments derived from Fraser Canyon placer mining during the 19th century gold rush (see section 7.3). It is often difficult to distinguish between human-induced changes in heavy metal concentrations and those produced by natural environmental conditions. Consequently, appropriate checks must be implemented by exploiting indicators unaffected by human activity to ensure there is no confusion with natural changes. A reference element, one uninfluenced by human activity, may be used to normalise metal concentrations, in order to remove natural fluctuations in the environmental signal. Previous studies of heavy metal contamination in coastal sediments have used aluminum as a reference element (Schropp et al., 1990; Hanson et al., 1993). Aluminum is an abundant element, has a strong, positive correlation with many other elements in natural sediments (Windom et al., 1989), and natural aluminum concentrations are not likely to be significantly altered by human activity (Schropp et al., 1990). Unfortunately, this is not the case in the Fraser River delta. Land clearance and forestry, both frequently accompanied by burning, remobilize aluminum from the soil (Schreier, Dec. 1997 pers. com.). The recent timing of the onset of these activities in the Fraser basin results in an overlap of this aluminum signal with that of heavy metal contamination from other human activities. 77 Consequently, aluminum is not an appropriate reference element in the Fraser River delta. Barium, on the other hand, also occurs widely in the natural environment, and is not widely used in industry, particularly the transportation industry, a major source of pollutants in the Fraser Valley. Normalising the down-core heavy metal concentrations with barium produces results which correspond reasonably well to those of heavy metal concentrations found in Burnaby Lake (McCallum, 1995) and the Strait of Georgia (Macdonald, 1991) and to those of other studies of the Fraser Delta (Turner, 1995 and Grieve and Fletcher, 1976). 78 Barber 27 Al(%) Fe(%) Zn(ppm) Cu(ppm) Mn(pprnl Hg(ppb) Pb(ppm) 200 4 250 -I - — , — . — . — . 0 2 4 0 2 4 0 60 120 0 40 80 0 600 1200 0 60 120 0 10 20 Al/Ba Fe/Ba Zn/Ba Cu/Ba Mn/Ba Hg/Ba Pb/Ba Woodward 21 Al(%) Fe(%) Zn(ppm) Cu(ppm) Mn(ppm) Hg(ppb) Pb(ppm) 250 i [ i i [ i — , — , — , — , i , , , , - . i n , , 0 1 2 3 2.5 3.5 4.5 40. 80 120 0 50 100 150 0 300 600 0 100 200 0 10 20 Al/Ba Fe/Ba Zn/Ba Cu/Ba Mn/Ba Hg/Ba Pb/Ba Legend unaltered metal concentrations — metal concentration/ Ba concentration Figure 4.9: Results of heavy metal analysis of cores Barber 27 and Woodward 21. 79 Duck 20 Al (%) Fe (%) — — jo | o to OJ y< o l / i o i / i o o o o © Zn(ppm) Cu(ppm) Mn(ppmL Hg(ppb) Pb (ppm) _ ui o — — OS vo tv> to Ov O KJ to to to ~q to -O — — to O O O O © U*i UN o-i U » > U 1 U 1 U 1 © 0 1 © U 1 0 ^ 7 ft j ! L T J Note: top value of Pb not shown is 404 ppm. 0 2 4 6 0 2 4 6 0 80 160 0 100 200 0 700 1400 0 100 200 0 20 Al/Ba Fe/Ba Zn/Ba Cu/Ba Mn/Ba Hg/Ba Pb/Ba Duck 31 Al (%) Fe (%) — — tO tO tO OJ OJ J> t o ^ o t o ^ L n o o i o - o o o v o o to o o o o o o o o o o o o o Zn(ppm) Cu(ppm) Mn(ppm) Hg(ppb) Pb(ppm) o 50 100 D. Q 150 200 250 to OJ OJ -fc. — o v u i o u i © j > a s o o o — to o o o o o o o o o o o o 0 1 2 3 4 5 0 1 2 3 4 5 40 80 160 0 50 100 0 300 600 0 50 100 0 10 20 Al/Ba Fe/Ba Zn/Ba Cu/Ba Mn/Ba Hg/Ba Pb/Ba — unaltered metal concentrations — metal concentration/ Ba concentration Figure 4.10: Results of heavy metal analysis of cores Duck 20 and Duck 31. 80 Westham 29 Westham 30 Al (%) Fe (%) N J N> O J U> Zn (ppm) Cu (ppm) Mn (ppm) — — — M to O N O O O N ) O O O O o o o o o o o o o o © Hg(ppb) Pb(ppm) <~n o ! j j 250 0 2 4 6 10 30 50 0 100 200 0 250 500 0 350 700 0 150 300 0 10 20 Al/Ba Fe/Ba Zn/Ba Cu/Ba Mn/Ba Hg/Ba Pb/Ba Legend unaltered metal concentrations — metal concentration/ Ba concentration Figure 4.11: Results of heavy metal analysis of cores Westham 29 and Westham 30. 81 Lulu 33 Al(%) Fe(%) Zn(ppm) Cu(ppm) Mn(ppm) Hg(ppb) Pb(ppm) 250 J — , — , — , — , H , , , , , - . 1 — : 1 0 4 8 0 4 8 12 0 100 150 200 0 100200300 0 500 100 0 350 700 5 25 45 Al/Ba Fe/Ba Zn/Ba Cu/Ba Mn/Ba Hg/Ba Pb/Ba Legend — unaltered metal concentrations — metal concentration/ Ba concentration Figure 4.12: Results of heavy metal analysis of core Lulu 33. 82 C H A P T E R 5 S E D I M E N T C O R E D A T I N G 5.1 Introduction In order to determine the impact of river training on marsh sedimentation, it is necessary to identify the sections in the cores which correspond with the various periods of river training. As determined in Chapter 2, the major periods of river training are as follows: 1) Prior to 1880 - unaltered, no river training; 2) 1880 to 1910 - small scale, localised dredging, and channel dams on tidal flats; 3) 1910 to 1954 - major dredging and construction of major river training works; 4) 1954 to 1996 - extensive dredging, but little further river training other than the construction of the Trifurcation Wall at Annacis Island. 5.1.1 Dat ing approach A major challenge of this study was to provide an accurate dating system for the cores. 1 4 C dating can provide long term records, as it has for the Fraser River delta (e.g. Williams and Roberts, 1989), but lacks short term resolution, rendering it useless for the time period of this study. Consequently, the initial plan for dating the cores involved using two radionuclides, 2 1 0Pb and 1 3 7Cs, both commonly used in marsh sedimentation studies (e.g. Chmura and Rosters, 1994; Allen et al., 1993; DeLaune et al., 1989). Pb, a natural isotope which forms part of the uranium-238 decay series, has a half life of 22 years and can provide dates within the last 150 to 83 200 years (Wise, 1980). Unfortunately, the Pb concentration in the samples analysed was very low, a tenth of the value required for chronological resolution. The average concentration in Fraser River marsh samples was 0.017 Bq/g, while the average concentration in a successful lake study in southern British Columbia was 0.166 Bq/g (Arnaud, 1997). The lack of 2 1 0Pb in the marshes of the Fraser River delta is due to the high rate of sedimentation relative to that of 2 1 0Pb input to the river from the atmosphere. Almost all the 2 1 0Pb in the sediment is from in situ decay of Ra, the parent isotope, and cannot be used for dating (Cornett, 1997 pers. com.). Consequently, another dating approach had to be developed. It was decided to attempt to create a time sequence for the cores using four different indicators, 1 3 7Cs, laminations, heavy metal concentrations, and sediment texture. 1 3 7Cs, if successful, would provide the location of the 1954 and 1964 levels (see section 5.2). Identification of the beginning of industrialisation based on heavy metal concentrations in the sediment would help isolate the early years of this century. Analysis of sediment texture would identify large flood deposits. Finally, if the laminations were proven to be annual couplets, they would allow years to be counted in continuously laminated sections of core. Individually the results from each of these techniques, which are presented in this chapter, are insufficient to date the cores. Combined, however, they are sufficient, as is shown in section 5.6. A fifth technique, identification of datable artefacts, was also attempted. Exposed channel banks in the marshes were searched for early evidence of sawn wooden planks, which might indicate the marsh level at the time of European colonisation. However, a native tree, Thuja plicata (western red cedar), naturally breaks into pieces resembling planks, making casual identification of sawn planks almost impossible after more than one hundred years of burial in marsh sediments. Although other techniques exist which may have also provided dates, such as 84 pollen analysis to identify the introduction of foreign species, and thermoluminescence, they were not employed due to the specialised procedures required, the labour intensity, or the cost. 5.2 Caesium Dating Caesium-137 ( Cs), artificially produced by atomic fission, has existed in the atmosphere since high-yield thermonuclear weapons testing began in 1952. Dating sediment cores using 1 3 7Cs relies on identifying the onset of 1 3 7Cs in sediment (measurable quantities were not present in soils prior to 1954) and horizons of peak concentrations, which correspond to periods of high nuclear testing activity, such as 1963/1964 and 1971 (Ritchie et al., 1990; Wise, 1980). 1 3 7Cs dating has been successfully carried out in Fraser River delta marshes by William and Hamilton (1995). They found no evidence of downward diffusion of the 1 3 7Cs signal due to chemical remobilization or bioturbation. Initially two cores, Duck 31 from the islands and Westham 15 from the delta front, were analysed for 1 3 7Cs by T. Hamilton at the Pacific Geoscience Centre, in order to determine the success of the technique. The cores were analysed in 2 cm increments, which resulted in a dry weight of approximately 30 to 80 g per sample. The procedure is non-destructive, and samples were recovered for further analysis. Other cores were analysed for 1 3 7Cs at the Department of Chemical Engineering and Applied Chemistry, University of Toronto. Full core analysis was undertaken for core Lulu 33 using a standard sample size of 2 g. This proved to be too small and results, while identifying the 1964 level of peak activity, did not have the resolution necessary to identify the 1954 onset of 1 3 7Cs. Tests were successfully repeated on select samples using larger quantities (~ 30 g) in order to locate thel954 level. All other cores were analysed with the intent of identifying only the 1954 level. With this in mind, a probable 1954 level was identified in each core and samples were prepared to 85 bracket this location. Results were assessed in terms of being either "alive" or "dead". Dead samples, those below 1954, had readings less than the detection level of 6 Bq/g (the acceptable error for readings was +/- 6 Bq/g). All other results were considered live, and consequently above 1954. Results are shown in Figure 5.1. Data are in Appendix 6. 5.3 Laminations Laminations visible in the cores from the Fraser River marshes typically consist of alternating clayey-silt and sandy-silt layers. In the upper portions of the cores, the sediment becomes finer and more organic rich. Frequently, layers of dense organic material are evident. These are interpreted to be the accumulation of a year's herbaceous growth, which dies in the autumn and is buried by the winter and spring sediment deposition. X-ray techniques, used to expose laminations not otherwise visible, as described in section 4.4.2, were particularly useful in the organic rich sections. In order to use the laminations as a dating technique, it is necessary to prove that they are annual couplets, consisting of a coarser layer deposited during the freshet and a finer layer deposited during the rest of the year. Often an organic layer is associated with the couplets. Examples of the results of comparing the 1954 1 3 7Cs level with that of the 42nd couplet (1954 to 1996) are shown for cores Duck 31 and Westham 30 in Figure 5.2 (see Figures 5.5 to 5.8 for results of other cores). In most cases the 1 3 7Cs date is slightly higher in the core than the couplet count, but it is so close in all but one core, Woodward 21, that it proves that the couplets are indeed annual. The difficulty of distinguishing and counting the couplets accurately in the densely organic material at the top of each core is the most likely reason for the couplet count falling below that of the , 3 7 Cs 1954 level. 86 5-7 14-16 f 34-36 I •s Q o. E f Q I a. D B a r b e r 27 1954 10-12 20-22 1 0 Bq/kg 2 0 D u c k 20 30 1954 0 10 Bq/kg 20 W o o d w a r d 21 30 34-36 44-46 64-66 74-76 10 20 Bq/kg W e s t h a m 15 30 40 1.5-3.5 4-5 5-6.5 6.5-8.5 T 8.5-10.5 [ 10.5-12.5 12.5-14.5 14.5-16.5 16.5-18.5 18.5-20.5 20.5-22.5 22.5-24.5 24.5-26.5 26.5-28.5 36.5-38.5 1 1964 1954 5 Bq/kg io W e s t h a m 29 15 30-32 40-42 50-52 "j 954 E O f f & D u c k 31 0-2 2-4 4-6 6-8 8-10 10-12 12-14 14-16 0 16-18 18-20 | 20-22 22-24 | 32-34 40-42 48-50 58-60 1964 1954 0 10 20 Bq/kg 30 40 L u l u 33 0-2 44-46 46-48 48-50 54-56 60-62 64-66 68-70 74-76 78-80 1954 1sl attempt: insufficient resolution for 1954 0-2 8-10 ' 16-18 24-26 32-34 48-50 E3 1964 (34-36cm) 0 20 40 Bq/kg 1 0 Bq/kg W e s t h a m 30 20 30 20-22 'S * 30-32 f cS 40-42 50-52 1954 10 20 Bq/kg 30 10 D n 20 Bq/kg 30 Figure 5.1: Results from 1 3 7Cs analysis. Note: Duck 31, Westham 15 and Lulu 33 were analysed continuously downcore, hence identification of 1964. In all other cores the sample interval is not continuous, so 1954 can only be identified as a region between samples 87 250 ^ 1954(137Cs) 3 3 150 _ Duck 31 0 0 20 40 60 80 100 120 140 160 180 200 220 240 depth (cm) 250 1954(I37Cs) „ 200 1 Westham 30 0 20 40 60 80 100 120 140 160 180 200 220 240 depth (cm) Figure 5.2: Examples of correlation between cumulative couplets and 1954 137Cs results. 5.4 Heavy Metal Concentrations The purpose for analysing for heavy metals is to identify the onset of industrial activity, which began in the Fraser Valley area in the early 1900s, in order to provide a date in the lower portion of the cores. The method of analysis and the results are described in section 4.4.3.4. In order to identify the beginning of human-induced sediment contamination, one would ideally hope to find a steady natural background signal at the base of the core, with an increase in metal concentrations towards the top of the core. The beginning of the increase in metal concentrations would be the point at which human-induced contamination began, barring any natural changes in the sediment chemistry. In the Fraser River cores this pattern is most clearly demonstrated by zinc and aluminum. The ability to identify the early 1900s using analysis of heavy metal concentrations in the Fraser River delta is confirmed by comparing results from the delta with those of two neighbouring environments, Burnaby Lake (McCallum, 1995) and the Strait of Georgia (Macdonald, 1991) (Figure 5.3). Burnaby Lake is in a small urban watershed 88 in the Greater Vancouver Regional District, which drains into the Fraser River near the head of the delta, and the Strait of Georgia is the body of water into which the Fraser River drains. Both these environments were cored during the last two decades and successfully dated using 2 1 0Pb. Not surprisingly, the Fraser marsh results are more similar to those of the Strait of Georgia, which also has a large catchment basin, than they are to those of Burnaby Lake, with its intensely urbanised watershed. Sediment core heavy metal data also exist for the tidal flats fronting the Fraser River delta (Grieve, 1977) and for marshes along the North Arm of the Fraser (Turner, 1995). Unfortunately neither study is useful as a comparison for dating purposes. The study of the North Arm provides only a 1964 1 3 7Cs date for one core, and the tidal flat study does not provide dates at all. Identification of the beginning of industrial activity using heavy metal analysis can be seen for each Fraser River delta core from this study in Figures 5.5 to 5.8. 5.5 Sediment Texture The methodology and results of grain size analysis were presented in section 4.4.3.3. One of the results of determining the grain size distribution was the identification flood deposits. Two exceptionally large floods have occurred within written history, one in 1894 and the other in 1948. All the core sediment records show thick sandy deposits within the finer marsh deposits. If such deposits occurred in only a few cores or in dramatically different levels within the cores, one would assume that they were channel deposits. However, photographic evidence dating back to 1930 (air photos) suggests that no channels have existed in the core locations since this date. The intra-marsh channels today are very stable, steep-sided features, the beds of which are deeper than many of these sandy deposits. In addition, the beds of these contemporary channels tend to be muddy rather than sandy. 89 Depth (cm) c N it a. o <D o pper o o U m o o -> o E 2 3 O qd„, Depth (cm) I I I I I I I o o o o ON t-~ v> co G\ 0\ G\ I I I I I I I I I o o © o o — o r-» «ri c-> o\ oo oo oo oo E a . o. s •a u _1 Depth (cm) S3JEQ q j Depth (cm) _o o o ON 2 o a oo (3 00 O ~ "S ° 2 -O es a> -a O « O £ s" c3 o CJ .2 •2 8 § o in o ON o '3 C/3 qd„, qd„, J . S CJ . CJ CJ ^ E cj 03 Cv) CJ •ii e -a 5 CJ 3 E • — 2 P'SJ O ^ o ° <£ o G -2 S +! O cj g cS cn u. cj - 3 fc g « C • s 'S £ £ S s — o c M a x> 3 11^ ~ .2 -g to "3 »3 W| fJ . . 1 3 cj cj O 90 All of these facts, in conjunction with the fact that the upper of these sandy deposits (or the 1948 flood deposit), found in Barber 27 and Westham 29 and 30, occurs immediately below the 1954 137 Cs level, indicates that they are indeed flood deposits. The grain size distribution of one core, Westham 30, with the flood deposits indicated, is depicted in Figure 5.4. Grain size and flood data for all the other cores can be seen in Figures 5.5 to 5.8. Cores Duck 20 and 31 were protected by the Woodward Training Wall and Dam at the time of the 1948 flood, which may explain why sandy flood deposits are not visible in these cores. Similarly, Lulu 33 was isolated from the main channel by the Steveston North Jetty by 1948. Woodward 21 was also protected by Woodward Training Wall and Dam in 1948, but was at a much lower stage in marsh development (i.e. lower relative to water level) and more vulnerable to flooding. Consequently recent flood deposits are visible in this core. depth (cm) Figure 5.4: Grain size distribution showing sand deposits from large floods. 125-250 um best indicated flood activity. 5.6 Chronological Synthesis Individually each of the dating techniques discussed is inadequate to provide sufficient dates to identify the required time periods: prior to 1880,1880 to 1910, 1910 tol954, and 1954 137 to 1996. 1954 ( Cs) is the only date determined by a technique able to stand alone without 91 corroboration by an independent dating method. It is the combination of the various approaches which provides the required dates. 5.6.1 Combina t ion of Techniques Figures 5.6 to 5.12 combine the four dating techniques used in this study, 1 3 7Cs analysis, annual couplets, heavy metal contamination, and grain size distribution. 1 3 7Cs analysis indicates the 1954 level in all eight cores analysed (Barber 27, Duck 31 and 20, Woodward 21, Lulu 33 and Westham 15, 29 and 30), and the 1964 1 3 7Cs position in two of those (Duck 31 and Lulu 33). Flood data, derived from grain size analysis, provides 1894 dates for all but Woodward 21, which is not sufficiently deep to include this deposit. Sediment analyses of heavy metal concentrations isolate the beginning of industrial activity in the region, approximately 1910. And, finally, proving that the laminations are in fact annual couplets allows years to be counted within sections of uninterrupted laminations in all the cores (see section 6.2.4). 5.6.2 Extrapolat ion of Dates to Other Cores Now that eight cores (seven vibrocores and Westham 15, from the reconnaissance field season) have been successfully dated, it is possible to extend much of this dating knowledge to the other nine cores via core correlation based on environmental magnetic susceptibility and visual assessment of core sediment texture. Figures 5.9 and 5.10 show the correlated cores. It is important to note that core depths are not corrected for the compaction resulting from coring procedures and natural settling due to the weight of the marsh sediments. The reason the cores have not been corrected for compaction is that sediment with different densities will compact at different rates, making it almost impossible to accurately correct. In addition, the sequence of events, which is important for establishing a chronology, is unaffected by compaction. 92 o o o o o o o N O OO « » N f l tN CN — — O O o © o © o o o © w> © w") © m m tN CN — — 0/„ 3Z|S }U3UIip3S %IV (uidd) uz 93 sjaidncQ C N •a OS -a o o c ca C N ca x> S3 OQ o ca 3 .a-'c JS o u 60 e '-4-* cj T3 T3 U C o o ca JS ca 8 3 E a. u Q E E "(N — (N 3. g o m i 55 i CN 00 <N O I "fr A — — vo rf V sC> n^ O \ 0 vO vO v^ O 0 S* 0S" 0S* O- Q*V BO/IV rf o (N —' o o o o ©' o ©' o - I — I — I — h -eg/uz in m — ©' C3 CD CQ 31 H 1 h o o o o o o «-> o >n o <n o r-i <N — —! o ©' l l l l o o o o o o o M O M VO ^ N 5 -s o S r-l w r-l u~ o o o 00 © vo o O.T3 3 tn U 0 3 u S ° a I S |«§ —• c u vo JS • -— 3 .2 -S <<- t. o o ca © -o I O : 00 2<g © VO © © IN "co J s O K o/0 azis juauiipas %IV (uidd) uz ^g/oz — — o o o © o o >n © m CN — — S}3]dncQ SAjiernuinQ a . '3 o o — ^•2 •5 i i I T3 o c cd O u o © © © © o © © •n © %n © vj © <N r-i —'• —I ©' ©" o/0 3ZJS JU3UIJP9S %IV o o © o © o o N O OO VO * N (uidd) uz a . u Q J 4 o 3 Q T 3 c CO O CN J* O 3 Q o o cn <D 3 2" ' S J 5 o CD 60 C -a o c IS £ o o u J= 3 « VO in fi 3 ,60 tu 94 eg/IV B8/DZ CN — — O en B T3 § ON CN -c O o 3 a* o CU 60 CO •o t> .a e o o u a; e 3 o/ 0 3 Z | S jnsraipss %IV ( m d d ) u z s^ 3idno3 aAjjemuin^ 95 %>2500um %180-250um| %125-180um %125-60um %4-60um %<4um Depth (cm) 0 20 40 i 1 r 60 80 100 120 140 160 180 200 220 1954 C"Cs) i Note: sandy section between ~1910 100 and 170 cmis interpreted (metals)| as disturbance due to the construction of Steveston 1894 North Jetty (1912-1932). (flood) Interval between Cs1 3 7 samples Flood deposit bed thickness Approximate1 1910 level ! Figure 5.8: Results of the combined dating techniques for core Lulu 33. 96 Those cores which were not subject to detailed analysis (Barber 28, Duck 23, Woodward 22, 26 and 32, Lulu 34, Reifel 24 and 25, and Canoe Pass 35) were visually assessed for any dramatic changes in sediment texture in order to identify potential flood deposits and changes in channel patterns. Woodward 32 lies in the old Woodward Slough, the major shipping channel until it shifted to the northern route in the early 1920s. An abrupt change in the sediment texture of this core from sand to finely laminated silts and sands at 58.5 cm below the surface (not corrected for compaction) (see Figure 4.3), is interpreted to be the result of the closure of Woodward Slough by Woodward Dam in 1927 immediately upstream of the core site. In the same year, hydraulic fill was placed on Woodward Island to seal new channels which were threatening to cut across its width. In Woodward 22, a thick silty layer, unlike sediment observed in any other core, is interpreted to be reworked sediment from this hydraulic fill, providing a date of 1927 for the base of this layer. Reifel 25, from the low marsh south of the Steveston South Jetty, is continously laminated the length of the core, enabling a core base date of 1964 to be established by counting couplets. Reifel 24 is also well laminated, and in this core dates for 1964, 1954 and 1943, the base of the laminated section, are established. 97 98 99 CHAPTER 6 SEDIMENTATION RATES AND MARSH DEVELOPMENT 6.1 Introduction In order to determine whether dredging and river training structures have had an impact on the development of marshes in the Fraser River delta, it is necessary to know the marsh sedimentation rates and patterns of growth. Theoretically, as a marsh grows in elevation relative to water level, both the total sedimentation rate and the mean grain size decrease as inundation becomes less frequent. This is a very general statement, and one that assumes no change in sediment source and supply, and no drastic changes in marsh hydrology: increased ponding, for example, may increase local sedimentation rates. Changes in substrate texture, sedimentation rate, and inundation frequency are reflected in a change in marsh vegetation. Unlike sedimentation rates in more slowly changing environments, such as lake beds, marsh sedimentation rates naturally change over relatively short periods of time even with no fluctuations in sediment delivery to the marsh region. Consequently, changing sedimentation rates and patterns are not necessarily the result of human activity. However, sudden shifts or changes in these rates and patterns indicate a sudden alteration in sediment delivery or depositional conditions, which may be the result of human activity. In this chapter, sedimentation rates and patterns are presented based on the dating scheme developed in Chapter 5 and links to river training structures and dredging are explored. 100 6.2 Sedimentation Rates A compounding factor in determining marsh depositional history is compaction, which occurs naturally under the weight of marsh sediments. Local subsidence of the Fraser River delta under its own weight has been estimated at 1.45 mm/a by repeated geodetic levelings (Mathews et al., 1970). Correction for natural compaction is not simple, since compaction rates vary depending on depth, length of burial, weight of overburden, and material characteristics such as porosity and organic content. Compaction of the cores also resulted from the vibrocoring procedure, as demonstrated in Table 4.1. In order to avoid the problems of compaction, rates will be presented in terms of mass per unit area per year (g/cm2/a) where possible. For comparison purposes, rates are also presented in terms of depth corrected for coring compaction per year (cm/a). It is assumed that coring compaction was uniform throughout the core, because of the difficulty of determining variable compaction rates. Correction for natural compaction is not attempted. Manipulation and control of the deltaic portion of the Fraser River has occurred in four phases, as identified in Chapter 2. These are: 1) Prior to 1880 - unaltered, no river training; 2) 1880 to 1910 - small scale, localised dredging, and channel dams on the tidal flats; 3) 1910 to 1954 - major dredging and construction of major river training structures; 4) 1954 to 1996 - extensive dredging, but little further river training other than the construction of the Trifurcation Wall at Annicis Island. Sedimentation rates for each of these periods are presented (Table 6.1) and discussed, starting with the most recent period, 1954 to 1996. Dating constraints limit the calculation of sedimentation rates prior to 1894, the date determined by flood deposits. Consequently, sedimentation rates are presented for 1894 to 1910 rather than 1880 to 1910. Attempts to 101 calculate sedimentation rates prior to 1894 will be discussed in section 6.2.4. The sedimentation rates discussed in this chapter are based on the inorganic, or mineral, portion of the sediment, because a large portion of the organic matter is produced in situ and, therefore, does not necessarily reflect changes in sediment delivery. Marsh developmental stages mentioned in the following sections are explained in section 6.3. Table 6.1: Sedimentation rates for river training periods. core date depth (cm) years (a) uncomp. depth (cm) total accretion (g/cm2/a) inorganic accretion (g/cm2/a) annual growth (cm/a)** Barber 27 * 1954-1996 0-11 42 12 0.26 0.24 0.29 1910-1954 11-52 44 49 1.32 1.27 1.11 1894-1910 52-60 16 9 0.73 0.71 0.56 1709-1894 60-177 185 137 0.83 0.81 0.74 Duck 20 1954-1996 0-16 42 22 0.33 0.31 0.52 1910-1954 16-90 44 100 2.03 1.98 2.27 1894-1910 90-108 16 24 1.74 1.72 1.50 Duck 31 * 1954-1996 0-16 42 26 0.17 0.16 0.62 1910-1954 16-70 44 87 1.03 0.99 1.98 1894-1910 70-92 16 58 1.30 1.28 3.63 pre 1894 0.23-0.5 Woodward 21 1954-1996 0-52 42 58 1.73 1.66 1.38 1910-1954 52-230 44 199 7.17 6.91 4.52 Lulu 33 1894-1910 0-52 42 65 1.27 1.20 1.55 1910-1954 52-200 44 184 5.65 5.55 4.18 1894-1910 200-224 16 30 2.11 2.05 1.88 Westham 29 1954-1996 0-46 42 81 1.01 0.95 1.93 1910-1954 46-105 44 106 2.10 2.05 2.41 1894-1910 105-125 16 36 2.00 1.96 2.25 Westham 30 1954-1996 0-46 42 84 1.14 1.10 2.00 1910-1954 46-100 44 99 2.05 2.01 2.25 1894-1910 100-136 16 66 3.52 3.46 4.13 * see section 6.2.4 for explanation of the pre 1894 values. In Duck 31 a range of couplet frequency is shown. ** core depth was corrected (uncompacted) for coring compaction in order to determine annual growth (cm/a). 6.2.1 1954 to 1996 During the period 1954 to 1996, the primary river training activity was dredging. By 1954 the main training structures, the dykes, jetties and training walls directly affecting the study 102 area were in place. The only major training structure built during this period was the Trifurcation Wall, constructed in 1967-1970 at the upstream end of Annacis Island, 16 km upstream from the study area. The purpose of this structure is to divide the flow between the North and Main Arms of the river, and to promote local scouring, reducing the need for dredging the channel adjacent to Annacis Island. It is unlikely that the construction of the Trifurcation Wall had much impact on the marshes at the mouth of the river. Table 6.2 shows the sedimentation rate of inorganic material in the marshes for each core over the period 1954 to 1996. The cores from the high marsh environment exhibit a slower rate of sedimentation, with an average of 0.24 g/cm /a, than those from the middle and low marshes, which have an average rate of 1.23 g/cm2/a. This difference is understandable, given the higher elevation of the high marsh areas relative to water level, and the consequent decrease in inundation time. Table 6.2: Inorganic sedimentation rates for river training periods showing marsh developmental stage. date 1954 to 1996 1910 to 1954 1894 to 1910 core g/cm /a marsh stage g/cm2/a marsh stage g/cm /a marsh stage Islands Barber 27 0.24 high 1.27 middle to high 0.71 middle Duck 20 0.31 high 1.98 middle 1.72 sand Duck 31 0.16 high 0.99 middle to high 1.28 sand to low Woodward 21 1.66 low to middle 6.91 tidal flat channel Front Lulu 33 1.20 low 5.55 tidal-sand-low 2.05 tidal flat Westham 29 0.95 middle 2.05 low to middle 1.96 sand to low Westham 30 1.10 middle 2.01 low to middle 3.46 sand to low Sedimentation rate changes during this period have been examined by Williams and Hamilton (1995) in a transect across the middle section of the marshes fronting Lulu Island. Their results, along with those of this study, are presented in Table 6.3. The time periods considered are those identified by 1 3 7Cs analysis, 1954 to 1964 and 1964 to present. An overall 103 decrease (average of 52 %) was found in the sedimentation rates at all the sites from the 1954 to 1964 rates to the 1964 to 1996 rates. Williams and Hamilton (1995) saw this decline in sedimentation rate as indicative of an eroding marsh, and pointed to increasing levels of dredging starving the marshes of sediment as the likely cause. There are, in fact, three possible explanations for such a decline in sedimentation rate over time. First, as mentioned before, it is natural to see a decline in sedimentation rate as the marsh elevation increases. In this case, however, one would not expect to find low marsh rates declining to levels lower than the earlier high marsh rates (average low marsh rates for 1954 to 1964 and 1964 to 1991/96 are 1.65 and 0.87 cm/a respectively, while average high and middle marsh rates are 1.25 and 0.61 cm/a respectively for the same periods). This overall drop in sedimentation rate does suggest that marsh sedimentation rates have been declining since 1964 beyond levels that might be explained by natural marsh elevation growth and natural sediment compaction. Table 6.3: Marsh sedimentation rates based on Cs dates from two studies. date 1954-1964 1964-1991 change in sediment-ation rate 1954-1964 1964-1996 change in sediment-ation rate marsh stage cm/a cm/a *cm/a *cm/a •core high 1.13 0.46 - 59 % Duck 31 middle 1.60 0.85 - 47 % 1.03 0.48 - 53 % Westham 15 low 0.80 0.63 -21 % 2.11 1.36 - 46 % Lulu 33 2.05 0.61 - 70 % tidal flats 1.00 0.26 - 74 % 0.60 0.33 - 45 % (Williams and Hamilton, 1995; data from marsh fronting Lulu Island) (this study) Secondly, it is possible that dredging, which is estimated to remove more bed material from the estuarine reaches of the Fraser River than is naturally delivered by the river (McLean and Tassone, 1991), is responsible for decreasing the sediment available for marsh growth. Dredging activity was relatively low between 1954 and 1964, the period when the marshes are 104 aggrading rapidly. On the other hand, dredging activity peaks between 1974 and 1994, when vertical marsh growth is slower. However, bed material in the Fraser River is fairly uniform in the lower reaches of the river: median grain size ranges between 250 and 350 um, and typically 97 % of the bed material is coarser than 125 um and 92 % is coarser than 177 um (Public Works Canada, 1989). Conversely, typical grain size of marsh sediment in the lower Fraser River is less than 60 um, suggesting that dredging of bed material primarily greater than 177 um in size is not going to result in depletion of sediment available for marsh growth. In fact, dredging may increase the amount of material in suspension, therefore increasing the amount available to be washed into the marshes, as was suggested by the rapid lateral growth of the marshes during the period of high dredging (1974-1994). However, while dredging may not have a direct impact on the amount of sediment potentially available for marsh growth, it does affect the sediment available for sand and tidal flats, and for the growth of the earliest stage of marsh development. Reduction of sediment availability and subsequent decline of these areas, which lie seaward of the marshes, would bring the marshes under increased wave attack, resulting in increased erosion. In addition, by increasing the channel cross section and the water prism, tidal currents in the marsh areas may be greater, possibly reducing sedimentation. Consequently, dredging could be responsible for reduced sedimentation rates in the Fraser River marshes by indirectly changing hydraulic conditions affecting the marshes. The fact that tidal flats have sustained the greatest decrease in sedimentation rate (an average loss of 63 % between 1954 to 1964 and 1964 to 1996) supports this hypothesis. Thirdly, it is possible that the decrease in marsh sedimentation rates over this period is, in fact, a relic of an earlier environmental change, that of river training structures, which were built primarily between 1910 and 1954. If river training structures created sheltered environments 105 conducive to marsh development, it is possible that a period of rapid marsh growth occurred following the construction of these structures. This possibility will be considered in more detail in sections 6.2.2, 6.3.1 and 6.3.2. If this did occur, explaining the high sediment rates between 1954 and 1964, it is possible that sedimentation rates would rapidly decrease as a new equilibrium between marsh growth and the new estuarine regime, initiated by the training structures, was achieved. If this is the case, then one would expect marsh sedimentation rates to return to levels similar to those of equivalent marsh stages prior to human interference. Most likely, a combination of these three explanations, natural marsh growth, dredging and river training structures, plays a role in the decrease seen in marsh sedimentation rates between 1954 and 1996. Study of earlier periods of marsh growth may shed some light on this situation. 6.2.2 1910 to 1954 Although dredging occurred throughout this period, the dominant factor was the construction of all the major river training structures in the study area (see Table 2.4 for dates and descriptions of training structures). Sedimentation rates during this period were generally higher than during any other period in the history of river management (Table 6.2). Average sedimentation rate for core sites which were middle to high marsh between 1910 and 1954 is 1.74 g/cm2/a. For those sites which were low to middle marsh sites during the same period, the -y average sedimentation rate was greater, 2.03 g/cm /a, while the average sedimentation rate was the greatest in the core sites which were still primarily sand or tidal flats, 6.40 g/cm2/a. Every core site, with the exception of the Westham Island sites, was directly affected by the construction of river training structures during this period. At the beginning of this period the main shipping channel, and the dredging activities which maintained it, was located in the central route, which is now Woodward Slough, running 106 between Duck and Woodward Islands. Woodward Island did not exist at that time in its present form. By 1918 the shipping channel had shifted to the northern route, where it is today, rendering Woodward Slough a backwater. The narrowing of Woodward Slough by wingdams on the south end of Duck Island in approximately 1910-1913, and the eventual closure of Woodward Slough by the Woodward Training Wall (completed in 1936) and Dam in 1927, dramatically changed the hydrologic conditions among the islands, creating a backwater suitable for marsh development, affecting the core sites on Duck Island. The period from 1910 to 1954 had the greatest sedimentation rates of any period studied in Duck 20. The same is true for Barber 27. While Barber 27 may not have been directly affected by the closure of Woodward Slough, changing hydrologic conditions, as the main channel shifted northward, and increased turbidity due to the construction activity would have affected this site. Woodward Island, both a cause and the effect of the shipping channel shifting to the northern route, grew rapidly once protected by Woodward Training Wall, as is demonstrated by the high sedimentation rate in Woodward 21 between 1910 and 1954 (6.91 g/cm2/a). Lulu 33 core site also underwent drastic changes during this period. Prior to 1912 this core site was open to the Main Channel and subject to currents created by the river and by waves from the south. After the construction of the Steveston North Jetty (the first and landward section was completed by 1914), which was completed by 1932, the core site was protected from the Main Channel. Although Luternauer (1980) found that sediment transport over the delta front was predominantly from south to north, Feeney et al. (1994) found that tidal currents just north of the Steveston North Jetty exhibited primarily east-west flow and frequent flow southward towards the jetty. Johnston (1921) stated that northwest winds, those second to the prevailing easterly winds in duration, most affected currents because of their long fetch. The impact of tidal and wind generated currents north of the Steveston North Jetty may have resulted 107 in sediment piling up against the newly built jetty, creating the high sedimentation rates found in Lulu 33 during 1910 to 1954. In addition, construction of the jetty would likely have disturbed the general area, resulting in an increase in sediment mobility, possibly explaining the sandiness of this section of the core. The Westham Island cores, while not directly affected by river training structures, were probably influenced by a reduction of sediment being transported south along the delta front from the Main Channel after the construction of the Steveston South Jetty (1930-1932 and 1954) and the Albion Dykes (1935 and 1936). Also the shift of the main channel from Woodward Slough to the northern route between 1910 and 1920 and the construction of the Kirkland Bifurcation in 1949 to maintain the focus of the river in the northern route, must have reduced the flow in Canoe Pass. This probably resulted in more stable conditions for marsh growth along the front of Westham Island. During this period, 1910 to 1954, rapid vertical accretion occurred at all the core sites, as a result of the construction of the river training structures, which altered the hydraulic conditions in the area. These elevated vertical sedimentation rates agree with the increased lateral accretion rates observed between 1930 and 1954, which were also attributed to the building of the training structures. The highest sedimentation rates occurred in Woodward 21 and Lulu 33, 6.91 g/cm3/a and 5.55 g/cm3/a respectively. Both these sites are immediately adjacent to training structures, which effectively isolated the sites from the main river channel. In the case of Lulu 33, disturbance of the sand flats by the construction of the Steveston North Jetty appears to have directly altered the sediment characteristics in this section of the core. 108 6.2.3 1894 to 1910 Although the period of initial river training activity occurred between 1880 and 1910, sedimentation rates cannot accurately be determined prior to 1894 due to dating constraints. No. 3 Dam (1900-1904) was built on the tidal flats to control the water flow through Hayseed Slough, north of the main channel. It is unlikely that this structure had much impact on the sedimentation rates of marshes fronting the delta since it did not impede sediment transport along the delta front. Between 1894 and 1910 dredging activity continued (~ 222,000 m3 per year for the whole of the lower Fraser River) (Public Works Canada, 1949). Sedimentation rates between 1894 and 1910 are 0.71 g/cm2/a for Barber 27, the only core site to have middle marsh development at that time. All other sites are sand or tidal flats grading into low marsh during this period. The average rate for sand flats grading into low marsh is 2.23 g/cm2/a. Tidal flats (predominantly muddy) and sand flats (sandy) have a combined average of 1.89 g/cm /a. Woodward Island was only starting to develop during this period, and Woodward 21 core site was in the main shipping channel through Sea Reach and Woodward Slough. 6.2.4 Prior to 1894 The main activities prior to 1894 were the construction of No.l and 2 Dams (1886-1894) on the tidal flats south west of Steveston in order to prevent the main channel from taking a southerly route across the tidal flats. Like No.3 Dam, these dams probably had minimal impact on the sedimentation rates of the marshes fronting the delta, since they also did not impede transport of sediment along the delta front. Dredging prior to 1894 was restricted to Woodward Slough (120,000 m3 in 1880), Ladner (19,430 m3 in 1892), and New Westminster (38,800 m3) (Public Works Canada, 1949). Only the dredging in the first two locations would have had any 109 impact on the study area. The volumes removed, however, are extremely small compared to modern dredging quantities of 4 million tonnes per year (McLean and Tassone, 1991). Due to the constraints of the dating system, no sedimentation rates can be confidently determined prior to 1894. However, x-rays of Duck 31 and Barber 27 do show laminations prior to the 1894 flood deposit. Barber 27 is at a low marsh stage of development during this period. In Barber 27, the laminations are very difficult to distinguish due to the nature of the sediment. Rates of 0.64 cm/a (0.74 cm/a corrected for coring compaction) appear to be accurate to a depth of 177 cm (not corrected). Below this point, from 177 to 180.5 cm, the sedimentation rate increases to approximately 1.0 cm/a. Using the sedimentation rate 0.64 cm/a, the date of Barber 27 at 180.5 cm, the point at which sand flats changed to a low marsh environment, is 1716. Given the difficulty of accurately counting laminae, it would appear likely that the low marsh in Barber 27 developed around 1700, the year of the last large earthquake to affect this area (Satake et al., 1996). Immediately below this level, the sediment is contorted (see Figure 4.3). In Duck 31, a sand flat prior to 1894, laminations suggest variable rates of sedimentation, ranging from 1.4 to 0.50 cm/a (2.3 to 0.81 cm/a corrected for coring compaction) interspersed with unlaminated sandy deposits. These sedimentation rates for Barber 27 and Duck 31 probably reflect low marsh and sand flat sedimentation rates in these areas prior to human activity. It must be remembered, however, that the cores have not been corrected for natural compaction, suggesting that the rates were actually higher at the time of deposition. 6.3 Sedimentation Patterns and M a r s h Development An alternate, and possibly more rewarding, approach to assessing the impact of river training on the marshes of the Fraser River delta, is to examine the stages of marsh development and to consider the cause of shifts from one stage to another. Based on organic content, 110 sediment texture and visual assessment of the sediments, marsh development stages have been assigned to the cores (Figure 6.1). These stages are, in increasing elevation: 1) Sand flat - less than 2 % organic content and predominantly sandy sediment; 2) Tidal flat - at the same general elevation as sand flats, but distinguished by silt and clay sediments, may have high levels of organic tidal detritus; 3) Low marsh - typically 2-4 % organic content, with alternate silt and sand layers; 4) Middle marsh - typically 4-6 % organic content, and predominantly silt and clay; 5) High marsh - usually greater than 6 % organic content, almost entirely silt and clay. This is a general scheme, based on both personal observations and the documented horizontal sequence of marsh developmental stages in the Fraser River delta (Hutchinson, 1982). Patterns of development seen horizontally across a marsh, seaward to landward, may be replicated vertically with increasing elevation above water level (Frey and Basan, 1985). This appears to be the case in the Fraser delta marshes. Development stages within cores were compared to modern surface environments to ensure they were accurately identified (see Table 4.2 for description of surface environments). For example, surface characteristics in Reifel 25 provided a model for low marsh deposits. Visual examination of the cores helped to distinguish between organic matter deposited in situ (e.g. roots throughout sample), and that from elsewhere, tidal or fluvial detritus (e.g. isolated thick organic, often woody, layers) (see Appendix 2). Because marsh vegetation communities vary between sites of similar marsh developmental stage, the organic content of the substrate also varies. Consequently, some cores depart from the proposed model. In these cases, specifically the surface environments of Barber 27 and Lulu 33, personal knowledge of the vegetation and substrate was used to determine the marsh stage. Lulu 33 is also finer grained than other cores of low marsh environments, because it is separated from the main channel of the river by the Steveston North Jetty. I l l 112 While each stage of marsh development below that of the surface environment probably existed in some form at each core site, only the dominant ones have been identified in Figure 6.1. For example, the middle marsh stage has been grouped in with the high marsh stage in cores Duck 20 and 31. On the other hand, since the stages are portions of a continuum, in some cores a marsh developmental stage is so long that it can be subdivided. This is the case in Lulu 33 where an upper low marsh stage can be identified, based on organic content and personal knowledge of the core site. In most cores, the shift between developmental stages appears to be fairly sudden, suggesting a response to a change in environment. It is the possible change in environment, driving the development of the marshes, which will be examined in the following sections. Sedimentation rates for the various marsh stages are listed in Table 6.4. Dates are determined by interpolation between closest known dates and by counting annual couplets where possible. 6.3.1 Marsh Development: Islands The Duck Island cores, 20 and 31, have very similar histories. Both were sand flats, or bars, prior to the turn of the century. In 1898 and 1897, Duck 20 and 31 respectively, a low marsh environment developed, initiated by deposits from the 1894 flood, which would have raised the surface elevation sufficiently for vegetation to take root. The growth of the low marsh on Duck Island was probably further enhanced by the construction of three wingdams (—1910-1913) at the southern end of the island, constricting flow in Woodward Slough and altering tidal flow patterns. Duck 31 core site, behind the remnants of these dams, probably benefited the most from the more sheltered environment created by the dams. A similar shift in marsh stage can be seen in Barber 27. Following the 1894 flood, Barber 27 developed from a low marsh 113 environment into a middle marsh environment. Again, it is likely that the 1894 flood deposit elevated the marsh surface sufficiently for a new marsh environment to develop. Closure of Woodward Slough in 1927, after the shipping channel was established in the northern route (c. 1918), would also have enhanced marsh development in these islands. Barber 27 became a high marsh environment in 1931, probably not directly as a result of the closure of Woodward Slough, but of the main channel becoming firmly established in the northern route. Table 6.4: Sedimentation rates for marsh developmental stages. core marsh date years depth uncomp. total inorganic annual stage depth accretion accretion growth (a) (cm) (cm) (g/cm2/a) (g/cm2/a) (cm/a)** Barber 27* high 1931-1996 65 0-35 40.87 0.67 0.64 0.63 middle 1894-1931 37 35-60 29.19 1.00 0.97 0.79 low 1709-1894 185 60-177 136.54 0.83 0.81 0.74 sand 180-234 63.06 Duck 20 high 1947-1996 49 0-25 33.11 0.47 0.44 0.68 low 1898-1947 49 25-85 79.47 1.46 1.43 1.62 sand 85-198 149.66 Duck 31 high 1940-1996 56 0-34 40.50 0.35 0.33 0.72 low 1897-1940 43 34-80 74.52 1.02 0.99 1.73 sand- 80-181.5 170.09 Woodward 21 middle 1972-1996 24 0-25 27.99 1.41 1.35 1.17 low 1950-1972 22 25-60 39.18 2.29 2.20 1.78 tidal 1912-1950 38 60-225 184.71 7.65 7.37 4.86 sand 225-230 5.60 Lulu 33 upper low 1961-1996 35 0-40 49.76 1.14 1.08 1.42 low 1936-1961 25 40-80 49.76 1.93 1.87 1.99 tidal 1912-1936 24 80-170 111.96 6.87 6.76 4.67 sand 170-238 84.59 Westham 29 middle 1949-1996 47 0-65 115.91 1.48 1.41 2.47 low 1907-1949 42 65-115 89.61 1.91 1.87 2.12 sand 115-155 71.33 Westham 30 middle 1950-1996 46 0-55 100.64 1.34 1.30 2.19 low 1890-1950 60 55-125 128.09 1.94 1.91 2.13 tidal 1870-1890 20 125-147 40.26 1.43 1.39 2.01 sand 147-160 23.84 * see section 6.2.4 for explanation of the pre 1894 values. ** core depth was corrected (uncompacted) for coring compaction in order to determine annual growth (cm/a). 114 In 1949 the flow into the island area was further decreased by the construction of the Bifurcation structure at the upstream end of Kirkland Island (in response to increased flow and erosion in Ladner Reach following erosion of Kirkland Island after 1919, which was exacerbated by the 1948 flood). Changes in flow patterns following 1927 appear to have resulted in a temporary decrease in organic content in the sediments of Duck Island, suggesting an increased inorganic deposition rate. This may have led to the establishment of a high marsh by 1940 in Duck 31. The high marsh in Duck 20 appears to have been initiated, or at least aided, by deposits from the 1948 flood, which appear as a fine grained, inorganic layer. The location of Woodward 21 was in the middle of the main shipping channel in 1894. As the main channel became established in the northern route, a sand bar developed at this site (c.1912). By 1922 a tidal flat was well established, probably aided by material deposited during the large 1921 freshet. The closure of Woodward Slough in 1927 and the protection of Woodward Island by Woodward Training Wall (1922 - 1936) resulted in the very rapid growth of Woodward Island. Sedimentation rates during this period, 7.37 g/cm2/a, are the largest recorded in these cores. In 1950, Woodward 21 became a low marsh environment, following the 1948 flood. In 1972, it then shifted to an upper low marsh aided by deposits from the large freshet of that year. 6.3.2 Marsh Development: Front Development of the marshes along the front of the delta follows a similar pattern. Westham 29 and 30 both shifted to a low marsh environment at the turn of the century from sand and tidal flats, probably caused by the 1894 flood deposits and the shift of the main channel from Ladner Reach to Woodward Slough in the 1880s. This shift would have resulted in a decrease in the flow through Canoe Pass, creating a more stable environment along the front adjacent to 115 Canoe Pass. Prior to this, Westham 30 experienced a short period of fine grained sediment deposition, with high organic content. The pattern of this sedimentation is consistent with that created by an object, such as a log, deposited on sand flats. Fine sediment and tidal detritus would have collected in the lee of the log for several years before the sand deposits associated with the 1894 flood buried them, raising the surface elevation sufficiently for marsh vegetation to be established. In both Westham 29 and 30, the evolution from low marsh to a middle marsh (albeit a marginal middle marsh), occurred immediately following the 1948 flood, suggesting once again that flood deposits play an important role in marsh development. The development of Lulu 33, on the other hand, is dominated by human activity. A muddy tidal flat with moderate organic content prior to 1912, Lulu 33's development shifted not to a marsh but to a sand flat. This shift coincides with the construction of the initial, landward section of the Steveston North Jetty (1912-1914). An erosional contact, visible at 178 cm depth (not corrected for compaction) suggests a sudden change in environment. Rapid sedimentation, as indicated by the annual couplets, over the next two decades is the second highest sedimentation rate found in the cores (6.76 g/cm /a). During the actual construction of the initial section of the jetty, the sedimentation rate was even greater, with 24.7 g/cm2/a deposited between 1912 and 1916. This translates into 16.3 cm of sediment per year (corrected for compaction). This rapid growth is attributed to changing circulation patterns as a result of the jetty. The increasingly sandy nature of the sediment is due to disturbance of sand flats by the construction activity. It is also possible that the site was used as a storage area for construction material or dredge spoil, but no record of such activity exists. By 1936, with the completion of the Steveston North Jetty in 1932, the site had stabilised and a low marsh developed. Sedimentation rates returned to values typical of a low marsh environment (1.87 g/cm2/a). Continued 116 sedimentation resulted in the upward growth of the marsh, which developed into an upper low marsh in 1961. 6.4 Conclusion Patterns of marsh development in the Westham Island cores, 29 and 30, which were the least affected by river training structures and dredging, suggest that the Fraser River marshes naturally shift rapidly from one stage to another, as opposed to experiencing a more gradual transition. Flood deposits appear to be the major catalyst for these shifts, as is seen in every core except Lulu 33. Flood deposits both increase the surface elevation, altering inundation patterns, and coarsen the sediment texture, increasing drainage. In addition, flood deposits bury existing vegetation, creating space for new colonising species. These changes may supply the environmental conditions required for a new marsh vegetation community to become established, resulting in a change in marsh type. Human-induced changes are primarily of two kinds, either a change in hydraulic conditions or a change in sediment delivery rates. Changing hydraulic conditions, the primary the consequence of river training structures, directly affected all the cores studied, with the exception of Westham 29 and 30. Growth patterns of Duck 20 and 31 and Barber 27 were influenced by the closure of Woodward Slough and the construction of the Kirkland Bifurcation. The development of Woodward 21 was directly linked to the construction of Woodward Training Wall and Dam, and Lulu 33 marsh is the result of Steveston North Jetty. However, the natural patterns of estuarine development, such as shifting channels and floods, were the primary impetus behind the development of these marshes. The river training structures simply furthered the process, and then stabilised it, possibly allowing for a longer period of uninterrupted marsh growth than would have occurred in a natural environment. For 117 example, erosion along Ladner Channel between 1919 and 1949, when the Kirkland Bifurcation was built, suggests that the main channel may have naturally shifted once again to a more southerly route, probably eroding marshes in this area. Lulu 33 is the sole exception. The growth of the marsh at this site appears to be in response to the construction of the Steveston North Jetty, rather than a natural event. There is no clear connection between dredging, which would mainly alter sediment delivery rates, and marsh development. In marshes primarily constructed of material less than 63 urn, it is unlikely that dredging channel bed sands decreases the sediment available for marsh aggradation. On the other hand, it is quite possible that, by disturbing the river bed, dredging actually increases the amount of sediment in suspension and, therefore, available to be washed into the marshes. However, the decline in sedimentation rate after 1964, a period which corresponds with the most active dredging (1974-1994), suggests that increased turbidity is not a significant factor in vertical accretion. Another factor to consider is the impact of dredging on sand flats. By removing sand which would otherwise have been distributed across the intertidal delta platform, dredging may be causing degradation of the sand flats and the lowest marsh areas which depend on fine sand for growth. If this is the case, which seems likely, degradation of these areas, combined with rising sea levels, will result in increased wave attack and erosion of the marshes, at least partially explaining the overall drop in sedimentation rate seen in the delta front marshes between 1964 and 1996. River training structures, by focusing the transport of sediment directly offshore, exacerbates this situation. Similarly, restriction of flow into the islands may also have resulted in a decrease in sedimentation rates, as is seen in Duck 31 since 1954. However, other possible explanations for this drop in sedimentation rate must be considered. It may be a result of a return to more typical marsh sedimentation rates, following the rapid marsh growth which occurred 118 between 1910 and 1954, the period which saw the construction of most river training structures in the study area. It is interesting to note that the trends in vertical marsh accretion do not correspond to the trends in river flow. Marsh sedimentation rates are high between 1910 and 1954, a period which is characterised by both high (1916-1925, and 1948-1954) and low (1925-1948) flows. Similarly, the period of decreased marsh aggradation (1964-1996) occurs during both high (1954-1977) and low (1977-1996) flow conditions. Another human-induced change in the river which has not been considered in great detail is the removal of large woody debris. Prior to snag removal, which began in 1880, large numbers of uprooted trees and logs were carried down the river during the annual freshet. Many of these were deposited on the tidal flats, where they may have created the protected environment required to initiate marsh growth. In 1792 Captain Vancouver reported that the front of the delta was covered with innumerable logs and stumps. Johnston (1921) also reported large numbers of logs in the river during the freshet, of which many were deposited on the marshes. Logs strewn across the marsh surface may have acted as a breakwater during periods of high wave activity. Contrarily, movement of such large debris during storms or periods of unusually high water must have created havoc as they dragged across the marsh surface. Today large woody debris is captured and contained by the Agassiz Debris Trap. Jetties and training walls also deflect floating debris away from the marshes, with the result that woody debris is no longer the factor in marsh sedimentation that it once was. 119 CHAPTER 7 HEAVY METAL: CONTAMINANT STORAGE 7.1 Introduction Heavy metal content of the core sediments was originally analysed with the intent of determining the onset of human-induced pollution, which successfully provided a date for the early 20th century (see section 5.4). In addition to this, heavy metal analysis has also resulted in some insight into sediment conditions prior to pollution and the impact of very early non-native human activity. These findings are by no means conclusive and are presented as preliminary results only, which should be pursued in future research. Estuaries located near urban areas have three main sources of heavy metals: natural weathering of rocks in the drainage basin, material transported by ocean and coastal currents, and waste produced by human activity (Deely and Fergusson, 1994). Most contaminants rapidly become associated with particulate matter and settle out of the water column (Hanson et al, 1993). Consequently, depositional environments, such as marshes, can provide long term storage for contaminated sediments. 7.2 Baseline Data One of the challenges in assessing human impact on the environment is obtaining background values with which to compare it. Due to the pervasiveness of human activity, it is becoming increasingly difficult, if not impossible, to find "natural, undisturbed" environments to 120 use as baselines in such assessments. The Fraser River delta is both a primary focus of urban-industrial development in British Columbia and a vital estuarine habitat. Little detailed information exists about deltaic environments prior to urbanisation and industrialisation. The earliest scientific study of the Fraser River delta is that by Johnston in 1921, which provides water quality data, but no information about heavy metal concentrations in the sediments. Consequently, there is no study prior to urban, industrial and agricultural development to provide baseline data. Other studies such as Grieve and Fletcher (1976) and Swain and Walton (1993) have sampled modern surface sediments for heavy metals, but have made no attempt to develop "natural-state" baselines. The size and geologic complexity of the Fraser's drainage basin make it impossible to find a comparable, uncontaminated surrogate and, consequently, there are no systems from which we can obtain comparisons in order to appraise human impact. In this situation, a viable way to create "natural-state" baselines for parameters, such as heavy metal concentrations, is to core into sedimentary environments which pre-date large scale human activity. Heavy metal analysis is discussed in section 4.4.3.4 and the identification of the beginning of human-induced contamination can be found in section 5.4 and Figures 5.6 to 5.9. 7.2.1 Developing Natural State Baselines With the onset of human-induced heavy metal contamination in the marshes clearly identified, it is now possible to assess the background conditions. Two cores, Woodward 21 and Lulu 33, did not extend below the level of human impact, and the record of another, Westham 29, is confounded by recurrent flood deposits. Since flood deposits appear to confuse the signal, particularly that of lead, they are avoided, where possible, when estimating background concentrations. Results for the remaining four cores are listed in Table 7.1. These 121 concentrations can be compared with surface values in order to assess the impact o f human activity. Core surface values and those from a B . C . Ministry o f the Environment study are shown in Table 7.2, demonstrating that there has indeed been a change in heavy metal Table 7.1: Background values of heavy metal concentrations. core depth (cm) Al (%)* Pb (ppm)* Zn (ppm)* Barber 27 56-190 1.34 ±0.18 8 ± 4 69.56 ±6.22 Duck 20 111-150 1.62 ±0.04 7 ± 2 83.00 ±2.02 Duck 31 111-150 1.61 ±0.16 8 ± 0 76.00 ± 4.06 Westham 30 106-145 1.37 ±0.32 7 ± 2 68.86± 11.81 * mean heavy metal concentrations in sediments below large scale human activity, (± 2 standard deviations). concentration since the onset of human-induced contamination. Lead levels have been dropping in the surface sediments o f the Fraser River delta as a result o f the phasing out of lead in gasoline, which culminated in complete elimination in 1990 (Swain and Walton, 1993). Lead concentrations appear to be higher in the core surface samples (16 ppm), than in the sediment of the adjacent Ewen Slough (8.34 ppm). This is most likely a factor o f the depth of the core surface samples, which effectively average concentrations over several years. Lead concentrations in Ewen Slough were 17 ppm in 1985 (Swain and Walton, 1993). Table 7.2: Heavy metal concentrations from surface sediment. core depth (cm) A l % Pb (ppm) Zn (ppm) Barber 27 0-5 2.41 12 92 Duck 20 0-4 2.21 16 100 Duck 31 0-4 2.02 16 100 Westham 30 0-3 2.2 10 92 Ewen Slough* 8.3 89 * Ewen Slough data collected in 1992, from slough bottom sediment. Sediment < 2 mm was analysed, of which 75.5% was < 63 nm (Swain and Walton, 1993). While these cores are sufficient to prove that the method is a valid one, they are neither long enough nor numerous enough to provide viable "natural-state" baselines for the Fraser River delta. One core, Barber 27, however, does have a sufficiently long history to provide good 122 baseline data for its location. This information is presented in Table 7.3 along with surface sediment metal concentrations for this site. Although the data presented are insufficient for statistical analysis, they are adequate to show that this approach will provide an acceptable method for determining "natural-state" baselines in the Fraser River delta. Further analysis of these and other longer cores will establish a set of baseline data which, in conjunction with ongoing surface sediment analysis, will improve assessment of human impact on the marshes of the Fraser River delta. Table 7.3: Background and surface heavy metal concentrations for Barber 27. Barber 27 * depth (cm) Al (%) Ba (ppm) Cu (ppm) Fe (%) Mn (ppm) Ni (ppm) Pb (ppm) Zn (ppm) background 56-190 1.34±0.18 112±18 32±6 2.87±0.52 320±86 43±10 8±4 69.56±6.22 surface 0-5 2.41 90 49 4.14 1145 53 12 92 *Barber 27 is the core with the longest history, and consequently the best background information. (± 2 standard deviations). 7.3 Mercury Contamination The presence of high mercury concentrations in several cores has led to speculation about the effect of gold mining in British Columbia on the Fraser delta marshes. Natural background levels of mercury in the marsh sediments appear to be 50 to 60 ppb. In four of the cores, Barber 27, Duck 20, Westham 29 and Lulu 33, mercury concentrations greatly exceed background levels at depths dating from the late 19th and early 20th centuries (Figure 7.1). The elevated concentrations vary from 100 to 320 ppb. Other areas of high mercury levels exist in the upper portions of the cores, dating from the latter half of the 20th century. This mercury contamination can be attributed to industrial and urban activity at that time. 123 7.3.1 Historical Use of Mercury The largest use of mercury prior to industrialisation in British Columbia was in placer gold mining. Mercury, or quicksilver, was employed to extract fine particles of gold from the sediment, because of its ability to "incorporate the gold within itself, while excluding foreign matter" (R.W. Paul, "Mining Frontiers of the Far West, 1848-1880" p.20, as cited in Galois, 1970). The gold was then extracted from the mercury by heating and the mercury was recovered to be reused. Mining practises involved moving large quantities of sediment and water through sluice boxes, rockers or pans in order to "wash" the gold from the matrix. Mercury was typically placed behind the riffles of the sluice box or rocker, or in a thin layer at the bottom of the pan (Galois, 1970). Discarded sediment was dumped or washed into any available water body, often the Fraser River or its tributaries Although nuggets and coarse gold could be recovered at the initial stages of the gold rush without the aid of mercury, it was used from the beginning, as is indicated by this comment in the San Francisco Newsletter, no.47, p.2, dated May 20 to June 5, 1858: at Hills Bar (3 miles south of Yale) men were "anxiously awaiting quicksilver [mercury] in order to accumulate $10 to $12 a day" (cited in Marshall, 2000). The mercury used in the Fraser River gold rush came from one source, California (Marshall, Dec. 1999 pers. com.). The large majority of the miners also came from California, where a gold rush began in 1849 in the eastern Sacramento River basin in the Sierra Nevada. These miners brought with them mining techniques which included the use of mercury, which was mined on the western side of the Sacramento River basin in the Coastal Mountains. 7.3.2 The Impact of Gold Mining in the Fraser River Basin In 1858, when the discovery of gold became public, an onslaught of gold seekers poured into British Columbia. Gold mining was initially focused on the gravel bars and terraces of the 124 Fraser Canyon region. As the easily accessible gold-bearing sediment was exhausted, hydraulic mining, using gravity pressurised jets of water to demolish terraces and wash sediment into sluices, became the predominant mining practise (Galois, Dec. 1999 pers. com.). A second gold rush occurred in the Cariboo in 1860, and this area quickly became the main gold mining region. The hydraulic mining period in the Cariboo was from 1877 to 1931, with a large investment in hydraulic mining occurring in the 1890s (Galois, 1970). Gold mining moved huge quantities of sediment, in some areas leaving behind nothing but fields of boulders where river terraces had once existed. Whole terraces were removed and the land surface lowered by several metres. The sediment, once the gold was removed, was washed into the Fraser River and its tributaries. Large quantities of mercury, which preferentially binds to fine sediment and organic matter, must have been washed into the river, although the objective was to retain the mercury and the gold along with it. There must also have been accidents involving spilt mercury. It is not conceivable that mercury did not reach the Fraser River. The quantities of mercury used in the British Columbia gold rushes are not known. However, during the California gold rush an estimated 3.5 x 106 kg of mercury was added to sediment during hydraulic mining between 1852 and 1884 (Bouse et al., 1997). In addition to disturbing and destroying large tracts of land, gold mining contaminated the environment. Elevated levels of mercury are found in both the river sediments and those of the receiving water bodies as a result of the California gold rush in the Sacramento River basin (Slotton, et al., 1997; Domagalski, 1998). Natural background levels of mercury in San Francisco Bay are 50 ppb (Bouse et al., 1997). In San Pablo Bay, a bay connected to San Francisco Bay and into which the Sacramento River drains, there are high levels of mercury, 300 to 400 ppb, in the sediments dating from 1850 to 1880. 125 126 The similarity of the San Pablo sediment signature to that of gold mining tailings in the Sierra Nevada indicate that the mercury contamination in San Pablo Bay is the result of the gold mining (Bouse et al., 1997). Hydraulic mining was banned in California in 1884. If gold mining in the Sierra Nevada introduced sufficient quantities of mercury to the Sacramento River to contaminate sediment deposited in San Pablo Bay, it is likely that the Fraser River gold mining also resulted in contamination. There are no major lakes or other large fine sediment sinks along the course of the Fraser River between gold mining areas and the Strait of Georgia. It is highly likely then, that mercury-contaminated sediment would have reached the delta area. Since the marshes are a primary depository of fine sediment and organic matter, it seems logical that mercury found in the marshes dating from the period of hydraulic mining is the result of such activity. th th There are other potential sources of mercury during the late 19 and early 20 centuries. Mercury is a naturally occurring element and very volatile. Land disturbance for purposes such as agriculture and forestry can produce flushes of naturally occurring mercury. The time period in question is also that when large areas of land were first cleared in British Columbia. It is possible that this activity also produced unusually high levels of mercury in the Fraser River. However, considering the potentially large quantities of mercury contaminated sediment introduced directly into the Fraser River by gold mining, it seems logical to assume that this is probably the main source of early mercury contamination in the marsh cores. Further research is required in order to eliminate any doubts as to the origin of the mercury. With the exception of Barber 27, the cores used in this study are from relatively young marshes. Cores from areas with older marsh deposits would help to establish the presence of a mercury-contaminated layer. Detailed chemical analysis of this layer and of mine tailings in the gold mining regions would irrefutably determine if placer mining is the source of the mercury. 127 In addition to mercury, mining activities may have resulted in abnormally high volumes of sediment in the river. As was mentioned earlier, huge amounts of sediment were moved during mining operations: in some locations the land surface was lowered by several meters. Within the delta, an unusually large influx of sediment evidently occurred between 1860 and the beginning of the 20th century, forming, for example, many of the islands in the study area (see Figure 3.2). The main channel shifted position several times during the late 19th and early 20th centuries, possibly the consequence of unusually high sedimentation rates during that period. Examination of the geomorphological changes wrought by the mining activities in the Fraser River basin would provide an estimate of the quantity of sediment washed into the river, and grain size analysis of undisturbed sediment in the mining area would provide an indication of how much of the mined sediment might have reached the delta. If such a study proved that large volumes of sediment mobilised by gold mining did reach the delta at the beginning of the 20th century, then the morphology of the main channel and the islands at the mouth of the Fraser River is the result of human activity beyond that of river maintenance. 128 CHAPTER 8 CONCLUSION 8.1 Conclusions A history of marsh development at the mouth of the Fraser River delta has been created, both in terms of lateral extension, through aerial photographs, and vertical growth, using sediment cores. By comparing this history with that of human activity and river management in the delta, the impact of such activity on marsh development becomes clear. Figure 8.1 illustrates the temporal relation between marsh growth, river regime, and river management activity. While much marsh has been lost as a result of dyking and land reclamation, there has been an overall lateral increase (6.7 x 106 m2) of marsh throughout the study area between 1930 and 1994. This research has not considered the loss of marsh due to dyking and land reclamation prior to 1930. Vertical marsh growth rates vary widely throughout the study area, with an average surface sedimentation rate of 0.80 g/cm /a. Marsh growth was greatest between 1910 and 1954, as indicated by both vertical and lateral accretion. During this period, river flow was primarily lower than average, although the second largest flood on record, that of 1948, occurred during this time. River training activity was at its peak between 1910 and 1954, but dredging activity was relatively low. Consequently, marsh growth can plausibly be attributed to the construction of training walls and jetties. 129 Year Marsh Lateral Accretion (Table 3.2) Marsh Vertical Accretion (Table 6.2) Fraser River Flow Characteristics (Figure 2.4) River Manage River Training Structures (Table 2.4) ment Activity Dredging (Figure 2.3) rapid growth ^ slower growth ^ rapid growth ^ slower growth ^ flow higher^ or lower ^ than mean high activity^ low activity ^ high activity^ low activity^ 1880 _ 1890 -1900 _ 1910 _ 1920 _ 1930 1940 _ 1950 _ 1960 _ 1970 _ 1980 _ 1990 _ 2000 _ + 26% A 155.4x10 m'/a | 1882 flood 1894 flood 1921 flood A i 1948 flood T 1972 flood i none small dams • on tidal flats 1 1880 0.16 x 10* m middle marsh 0.71 g/cm /a 1 flats-low marsh V 2.09 g/cm /a 0.23 x 10* m ^ middle-high marsh 1.41 g/cm /a low-middle A marsh 1 2.03 g/cm /a * flats 6.23 g/cm /a all major river training structures in study area t 1.55x 10* m ^ 1.75 x 10* m' ^ + 15 % _ 1 108.0x10 m/aV/ high marsh 0.24 g/cm /a ^ middle marsh 1.03 g/cm /a 1 Trifurcation at New Westminster and maintenance +20% _ A 161.5 xio' m'/a 1 4.48 xlO m | ( 1.79 x 10* m' ^ * accretion on intertidal flats is unusually high due to the rapid growth of Lulu 33 and Woodward 21, which were directly affected by river training structures. Figure 8.1: Relation between marsh growth, river regime, and river management. Much of the marsh growth has taken place in the lee of river training structures, which provide sheltered, stable environments. Training structures and dredging have also prevented natural migration of the river, allowing marshes to develop undisturbed for longer periods of time than might otherwise have been possible. This is evident in the growth of trees on Duck 130 and Barber Islands. If the river had been allowed to return its main channel to Ladner Reach, a move which was prevented by the construction of the Kirkland Bifurcation in 1949, the margins of these islands might well have been eroded, preventing marsh development from reaching the point at which it could support trees. After 1954, marsh growth slowed down. A change which coincides with a period of higher than average river flow. This suggests that marsh growth is not controlled by river regime, because sediment transport is usually greatest during high flow years. This study and that of Williams and Hamilton (1995) found an overall decrease in vertical marsh growth of 52 % between 1954 to 1964 and 1964 to 1991/1996. This reduction is beyond that expected as a result of reduced sedimentation rates due to increased marsh surface elevation and natural sediment compaction. It appears to be due to attainment of a new sedimentation regime under environmental conditions imposed by the river training structures. Lateral marsh growth has a different pattern: between 1974 and 1990 the rate of growth increased to a level similar to that of 1930 to 1954. This increase occurred at the same time as the most active period of dredging. Dredging removes material primarily greater than 177 um from the river bed, while marsh sediments are typically less than 63 um in size, suggesting that dredging does not directly starve the marshes of sediment. On the contrary, it may increase the turbidity of the water, putting more sediment into suspension, where it may be available for marsh aggradation. While greater turbidity does not have a noticeable effect on vertical marsh growth, it possibly increases the availability of fine sands, which are required for initiation of new marsh areas. However, stability of potential marsh habitat, as a result of the training structures, is the most probable cause for continued marsh lateral growth. Another potentially important factor is that dredging in excess of natural bed material input, as was the case between 1974 and 1984 (McLean and Tassone, 1991), may have a negative impact on sand flats and bars, 131 the base on which marshes develop. One would expect that such activity, combined with river channelization which prevents the natural distribution of sediment across the intertidal zone, would result in deterioration of sand flats, and eventually lead to the undermining of marshes. Undercutting, evident at many locations along the leading edge of the marshes, has been interpreted as a sign of marsh deterioration in the past (i.e. Williams and Hamilton, 1995). However it is probable that this is a natural process in the development of the Fraser River delta marshes. The ragged appearance of the leading edge of the marshes in all the aerial photographs since 1930, combined with the continuous lateral growth, suggest that this is the natural condition of these marshes. While river management, particularly river training structures, has played an important role in the development of all the marshes, it is important to remember that natural estuarine processes, such as shifting channels and floods, were the impetus behind the establishment of these marshes. Training structures have simply furthered the process and provided stability. The only exceptions are the Woodward and Lulu Islands sites, which have marsh sequences initiated by river training. Dependent on inorganic deposition for growth, marsh stage (i.e. high, middle or low marsh) is determined by deposition related to extreme events such as floods and the construction of river training structures. Relative sea level rise along the Fraser River delta is estimated to be approximately 3.7 mm/a (see section 2.2.2). This is a relatively conservative estimate compared to that of the Intergovernmental Panel on Climate Change (Gornitz, 1995). In an inorganic marsh, such as that of the Fraser River delta, a sufficient sediment supply is required in order for the marsh to maintain itself in the face of rising sea level. The average current sedimentation rate on the surface of the Fraser River marshes is 1.18 cm/a (0.80 g/cm2/a of inorganic material), suggesting that sedimentation rate is sufficient to maintain the marsh. 132 8.2 Summary of Findings This research has successfully established the following conclusions, with repect to the main hypothesis: 1) The effect of human activity, such as establishing and maintaining a shipping channel in deltaic environments, can be identified in the sedimentary record; 2) A combination of techniques, including 1 3 5 Cs, x-ray examination of laminations, human-induced heavy metal contamination, and natural event deposits, can be employed to successfully ") 1 ft date a marsh core when direct techniques such as Pb, which provides continuous downcore dating, fail; 3) Organic content, along with sediment size, provide an adequate surrogate for first hand evidence of historical marsh developmental stage; 4) Cores from undisturbed marshes can provide the information necessary for establishing baseline data in order to assess the impact of human activity, such as heavy metal pollution; and, 5) Vertical development of marsh stage, in marshes which are dependent on inorganic rather than organic deposition for growth, as in the Fraser River delta, is controlled primarily by extreme events, such as floods and training wall construction, as opposed to gradual sedimentation over time. Additional findings about the natural history of the Fraser River delta include the following: 6) River management in the Fraser River delta has affected marsh development, on one hand creating stable areas in the lee of training structures conducive to marsh development, while on the other, destroying marshes along much of the main navigation channel; 7) Dredging does not appear to have had a direct impact on marsh development in the Fraser River delta; 133 8) The areal extent of marshes in the study area are has been increasing at an average rate of 105 x 103 m2/a between 1930 and 1994; 9) The continued lateral growth of the marshes between 1930 and 1994 indicates that the ragged appearance of the leading edge of the marshes is not evidence of marsh deterioration; 10) Vertical marsh growth varies widely across the study area, with the lowest sedimentation rates found in the high marshes (average 0.24 g/cm2/a) and the highest rates found in the middle and low marshes (average 1.23 g/cm2/a); 11) Current average rates of vertical marsh accretion (1.18 cm/a) suggest that sedimentation is sufficient to maintain the marshes at the present estimated rate of relative sea level rise (3.7 mm/a); and, 12) Mining activity during the Fraser River gold rush in the latter half of the 19th century may have resulted in an unusually large volume of sediment being deposited in the Fraser River delta, including a layer of sediment with abnormally high mercury levels. This discovery requires further research. The first five of these findings are general in nature, providing information which may apply to other sand-body deltas similar to the Fraser River delta. The remaining points are specific to the marshes of the Fraser River delta. The insight they provide into the relationship between marsh development and human activity in this delta will help large scale human activity, such as the maintenance of an international port suitable for large ocean-going vessels, to co-exist with one of the largest marshes on the western coast of North America. The marshes of the Fraser River delta are important for many reasons. They provide a vital estuarine habitat for birds, fish and some mammals. They are an integral link in the Pacific Flyway, the annual migration path used by many bird species. The Fraser is the most important salmon spawning 134 river on the Pacific coast of North America, and the estuary is a vital component of the salmon habitat. From an economic point of view, in addition to the monetary value of the salmon, the marshes form a first line of defence against storms. Wave energy is dissipated by the marshes before it reaches the dykes, which protect valuable low lying land behind. For these reasons, it is vital to ensure that the marshes of the Fraser River delta are maintained in a healthy state. 8.3 Further Research This study has produced a number of questions which require further research. In order to ensure that the marshes of the Fraser River delta survive, it is important to determine the impact of dredging on the sand flats, to establish a possible link between dredging and any future marsh deterioration as a result of undermining. Monitoring of contemporary marsh growth, both vertically and laterally, would also help to determine the overall state of the marshes and their ability to survive in the future if the current environmental conditions change. Further analysis of longer marsh cores, using a technique such as that developed in this study, would provide information about the natural concentrations of heavy metals in marsh sediments. This would allow present levels of human-induced contamination to be assessed in terms of natural levels. Such analysis would also appraise the existence and extent of a mercury contaminated layer of sediment resulting from gold mining during the Fraser River gold rush. Similarly, establishing the extent of the Fraser River gold mining in order to determine the volume of sediment removed from the land by the mining process, might provide some insight into the impact of this sediment on the development of the delta in the late 19th century. Finally, developing a new estimate of marsh area prior to river management would allow overall change in marsh area during the last one hundred years to be assessed. 135 R E F E R E N C E S Allen, J. R. L., and Rae, J. E. 1986. Time sequence of metal pollution, Severn Estuary, southwestern UK. Marine Pollution Bulletin 17: 427-431. Allen, J. R. L., Rae, J. E., Longworth, G., Hasler, S. E., and Ivanovich, M. 1993. A comparison of the 2 1 0Pb dating technique with three other independent dating methods in an oxic estuarine salt-marsh sequence. Estuaries 16:679-677. Arnaud, E. 1997. Detecting the Effects of Forestry on Lacustrine Sedimentation on the West Coast of Vancouver Island, British Columbia. Unpublished M.Sc. Thesis, Department of Geography, University of British Columbia. 250p. Barrie, J. V. 1999. Human impact and recent geological evolution of the Fraser River Delta, British Columbia. Proceedings of the 1999 Canadian Coastal Conference, Victoria, B.C. 1: 277-293. Bouse, R., Hornberger, M., and Luoma, S. 1997. Sources of mercury in sediment cores from San Francisco Bay. Abstract # PWA058 in SET AC 18th Annual Meeting, San Francisco, California, p. 240. Bricker-Urso, S., Nixon, S. W., Cochran, J. K., Hirschberg, D.J., and Hunt, C. 1989. Accretion rates and sediment accumulation in Rhode Island salt marshes. Estuaries 12: 300-317. Bunting, M. J., Duthie, H. C , Campbell, D. R., Warner, B. G., and Turner, L. J. 1997. A palaeoecological record of recent environmental change at Big Creek Marsh, Long Point, Lake Erie. Journal of Great Lakes Research 23 (3): 349-368. Carr, A. P. 1980. The significance of cartographic sources in determining coastal change. In Cullingford, R. A. et al. (eds.) Timescales in Geomorphology. Chichester: Wiley and Sons. p. 13-29. Chapman, V.J. 1977. Wet Coastal Ecosystems. Amsterdam: Elsevier Scientific Publishing Company. Chmura, G. L., and Kosters, E. C. 1994. Storm deposition and 1 3 7Cs accumulation in fine-grained marsh sediments of the Mississippi Delta plain. Estuarine, Coastal and Shelf Science 39: 33-44. Church, M. A., McLean, D. G., Kostaschuk, R., Macfarlane, S., Tassone, B., and Walton, D. n.d. [1990] Channel stability and management of lower Fraser River: Field excursion guide. Water Resources Branch, Inland Directorate, Environment Canada. 99p. 136 Clague, J. J., Harper, J. R., Hebda, R. J., and Howes, D. E. 1982. Late Quaternary sea levels and crustal movements, coastal British Columbia. Canadian Journal of Earth Sciences 19: 597-618. Clague, J. J., and Luternauer, J. L. 1991. Postglacial deltaic sediments, southern Fraser River delta, British Columbia. Canadian Journal of Earth Sciences 28: 1386-1393. Clague, J. J., Luternauer, J. L., and Hebda, R. J. 1983. Sedimentary environments and postglacial history of the Fraser Delta and the lower Fraser Valley, British Columbia. Canadian Journal of Earth Sciences 20: 1314-1326. Clague, J. J., Naesgaard, E., and Sy, A. 1992. Liquefaction features on the Fraser delta: evidence for prehistoric earthquakes? Canadian Journal of Earth Sciences 29: 1734-1745. Coakley, J. P., Nagy, E., and Serodes, J.-B. 1993. Spatial and vertical trends in sediment-phase contaminants in the upper estuary of the St. Lawrence River. Estuaries 16: 653-669. Crowell, M., Leatherman, S. P., and Buckley, M. K. 1991. Historical shoreline change: error analysis and mapping accuracy. Journal of Coastal Research 7: 839-852. Cundy, A. B., Collins, P. E. F., Turner, S. D., Croudace, I. W., and Home, D. 1998. 100 years of environmental change in a coastal wetland, Augusta Bay, southeast Sicily: evidence from geochemical and palaeoecological studies. Geological Society Special Publication 139: 243-254. Davies, J.L. 1980. Geographical Variation in Coastal Development. 2nd edition, London: Longman. Deely, J. M., and Fergusson, J. E. 1994. Heavy metal and organic matter concentrations and distributions in dated sediments of a small estuary adjacent to a small urban area The Science of the Total Environment 153:97-111. DeLaune, R. D., Whitcomb, J. H., Patrick, W. H. Jr., Pardue, J. H., and Pezeshki, S. R. 1989. Accretion and canal impacts in rapidly subsiding wetland. 1.1 3 7Cs and 2 1 0Pb techniques. Estuaries 12: 247-259. Dionne, J-C. 1985. Tidal marsh erosion by geese, St. Lawrence Estuary, Quebec. Geographic Physique de Quarternaire 39: 99-105. Dionne, J-C. 1989. An estimate of shore ice action in a Spartina tidal marsh, St. Lawrence Estuary, Quebec, Canada. Journal of Coastal Research 5: 281-293. Domagalski, J. 1998. Occurrence and transport of total mercury and methyl mercury in the Sacramento River Basin, California. Journal of Geochemical Exploration 64: 277-291. Dorcey, A. H. J. 1991. Water in Sustainable Development: Exploring Our Common Future in the Fraser River Basin. Westwater Research Centre: UBC. 288 p. 137 Environment Canada 1999. Water Survey Branch Hydat CD ROM (1993) and Canadian Hydrological Data: Fraser River. Evans, M 1997. Sediment Yield and Geomorphic Sensitivity. Unpublished Ph.D. thesis, Department of Geography, University of British Columbia, Vancouver. 295p. Feeney, T. D., Amos, C. L., and Luternauer, J. L. 1994. Sediment pollution regime on the northern tidal flats, Fraser River delta, British Columbia, Canada. Proceedings, Coastal Zone Canada '94 Canadian Coastal Association, Halifax, Novia Scotia 3: 1273-1287. Fraser Basin Management Program, 1994. Review of the Fraser River Flood Control Program. Task Force Report, May 26, 1994 82p. Fraser River Estuary Study Steering Committee, 1978. Fraser River Estuary Study: Habitat. Faser River Estuary Study Steering Committee, Province of British Columbia and Government of Canada, Victoria. 181p. French, P. W., 1996. Implications of a saltmarsh chronology for the Severn Estuary based on independent lines of dating evidence. Marine Geology 135: 115-125. Frey, R. W., and Basan, P. B. 1985. Coastal Salt Marshes. In Coastal Sedimentary Environments. Davis, R. A. Jr. (ed.). Springer-Verlag, New York pp. 225-301. Gagliano, S. M. 1973. Environmental management in Mississippi Delta system. American Association of Petroleum Geologists Bulletin 57: 1830-1831. Gagliano, S. M., Smith, W. G., and Van-Beek, J. L. 1975. Contemporary shoreline change -Mississippi Area. American Association of Petroleum Geologists Bulletin 59: 1725. Galois, R. M. 1970. Gold Mining and Its Effects on Landscapes of the Cariboo. Unpublished M. A. thesis, University of Calgary, Calgary. Gibson, J. W., and Hickin, E. J. 1997. Intra- and supratidal sedimentology of a fjord-head estuary, south-western British Columbia. Sedimentology 44:1031-1051. Grieve, D. A. 1977. Behaviour of some trace metals in sediments of the Fraser River delta-front, southwestern British Columbia. Unpublished M.Sc. thesis. University of British Columbia, Vancouver. Grieve, D. A. and Fletcher, W. K. 1976. Heavy metals in deltaic sediments of the Fraser River, British Columbia. Canadian Journal of Earth Science 13:1683-1693. Gornitz, V. 1995. Sea-level rise: a review of recent past and near-future trends. Earth Surface Processes and Landforms, 20: 7-20. Grout, J. A., Levings, C. D., and Richardson, J. S. 1997. Decomposition rates of Purple Loosestrife (Lythrum salicaria) and Lyngbie's Sedge {Carex lyngbei) in the Fraser River estuary. Estuaries 20: 96-102. 138 Hanson, J.P., Evans, D.W., and Colby, D.R. 1993. Assessment of elemental contamination in estuarine and coastal environments based on geochemical and statistical modeling of sediments. Marine Environmental Research, 36, pp 237-266. Harris, C. 1997. The Resettlement of British Columbia: Essays on Colonialism and Geographic Change. UBC Press: Vancouver, B.C. 314 p. Harris, C. 1992. The Lower Mainland, 1820-81. In Wynn, G. and Oke, T. (eds.) Vancouver and Its Region. UBC Press, Vancouver, p. 38-68. Harrison, E. Z., and Bloom, A. L. 1977. Sedimentation rates on tidal salt marshes in Connecticut. Journal of Sedimentary Petrology 47: 1484-1490. Hart, B. S., and Barry, J. V. 1995. Environmental geology of the Fraser Delta, Vancouver. Geoscience Canada 22: 172-183. Hoos, L. M., and Packman, G. A.(eds.) 1974. The Fraser River Estuary: Status of Knowledge to 1974. Report of the Estuary Working Group, Department of the Environment. 518p. Hutchinson, I. 1982. Vegetation - environment relations in a brackish marsh, Lulu Island, Richmond, B.C. Canadian Journal of Botany 60:452-462. Hutchinson, I. 1988. The biogeography of the coastal wetlands of the Puget Trough: deltaic form, environment, and marsh community structure. Journal of Biogeography 15:729-745. Hutchinson, L, Roberts, M. C , and Williams, H. F. L. 1995. Stratigraphy, diatom biofacies, and palaeogeomorphology of a mid Holocene distributary channel system, Fraser River delta, British Columbia, Canada. Canadian Journal of Earth Sciences 32:749-757. Johnston, W. A. 1921. Sedimentation of the Fraser River Delta. Geological Series 107, Memoir 125, 46p. Kelly, J. T., Belknap, D. F., Jacobson, G. L. Jr., and Jacobson, H. A. 1988. The morphology and origin of salt marshes along the glaciated coastline of Maine, USA. Journal of Coastal Research 4:649-665. Kulikov, E. A., Fine, I. V., Rabinovich, A. B., Bornhold, B. D., and Thomson, R. E. 1999. Numerical simulation of submarine landslides and tsunamis in the Strait of Georgia. Proceedings of the 1999 Canadian Coastal Conference, Victoria, B.C. 2: 845-861. Ladner, E. G. 1979. Above the Sandheads. D. W. Friesen and Sons, Cloverdale, B.C. 181p. Leonard, L. A. 1997. Controls of sediment transport and deposition in an incised mainland marsh basin, southeastern North Carolina. Wetlands 17:263-274. Letzsh, W. S., and Frey, R. W. 1980. Erosion of salt marsh tidal creek banks, Sapelo Island, Georgia. Journal of Sedimentary Petrology 12:201-192. 139 Levings, C. D. 1980. Consequences of training walls and jetties for aquatic habitats at two British Columbia estuaries. Coastal Engineering 4:111-136. Luternauer, J. L. 1975. Fraser delta sedimentation, Vancouver, British Columbia. Report of Activities, Part B; Geological Survey of Canada, Paper 75-1B: 171-172. Luternauer, J. L. 1976. Use of aerial photographs to map sediment distribution and to identify historical changes on a tidal flat. Report of Activities, Part C; Geological Survey of Canada, Paper 76-IC: 29-304. Luternauer, J. L. 1977. Fraser delta sedimentation, Vancouver, British Columbia. Report of Activities, Part A; Geological Survey of Canada, Paper 77-1 A: 65-72. Luternauer, J. L. 1980. Genesis of morphological features on the western delta front of the Fraser River, British Columbia - status of knowledge. In McCann, S. B. (ed.), Coastlines of Canada. Geological Survey of Canada Paper 80-10: 381-396. Luternauer, J. L., and Murray, J. W. 1973. Sedimentation on the western delta-front of the Fraser River, British Columbia. Canadian Journal of Earth Science 10:1642-1663 Macdonald, R. W., Macdonald, D. M., O'Brian, M. C , and Gobeil, C. 1991. Accumulation of heavy metals (Pb, Zn, Cu and Cd), carbon and nitrogen in sediments from Strait of Georgia, B.C., Canada. Marine Chemistry 34: 109-135. Marshall, D. 2000. Claiming the Land, Indians, Goldseekers, and the Rush to British Columbia. Unpublished Ph.D. Thesis, Department of History, University of British Columbia. Mathews, W. H., and Shepard, F. P. 1962. Sedimentation of Fraser River delta, British Columbia. Bulletin of the American Association of Petroleum Geologists 46:1416-1443. Mathews, W. H., Fyles, J. G., and Nasmith, H. W. 1970. Postglacial crustal movements in southwestern British Columbia and adjacent Washington State. Canadian Journal of Earth Sciences 7: 690-702. McCallum, D. W. 1995. An examination of trace metal contamination and land use in an urban watershed. Unpublished MSc. Thesis, Department of Civil Engineering, U.B.C. 217p. McLean, D. G., and Church, M. 1999. Sediment transport along lower Fraser River 2. Estimates based on the long-term gravel budget. Water Resources Research 35: 2549-2559. McLean, D. G., Church, M., and Tassone, B. 1999. Sediment transport along lower Fraser River 1. Measurements and hydraulic computations. Water Resources Research 35: 2533-2548. McLean, D. G., and Tassone, B. L. 1991. A sediment budget of the lower Fraser River. Proceedings of the Fifth Federal Interagency Sedimentation Conference, Las Vegas. 2: 33-40. 140 Milliman, J.D. 1980. Sedimentation in the Fraser River and its estuaries, southwestern British Columbia (Canada). Estuarine and Coastal Marine Science 10: 609-633. Monahan, P. A., Luternauer, J. L., and Barrie, J. V. 1993a. A delta topset sheet sand and modern sedimentary processes in the Fraser River Delta, B.C. In Current Research, Part A; Geological Survey of Canada, Paper 93-1 A: 263-272. Monahan, P. A., Luternauer, J.L. and Barrie, J. V. 1993b. A delta plain sheet sand in the Fraser River Delta, British Columbia, Canada. Quaternary International 20: 27-38. North, M. E. A., Dunn, M. W., and Teversham, J. M. 1979. Vegetation of the Southwestern Fraser Lowland, (map) Environment Canada. Northwest Hydraulic Consultants. 1999. Lower Fraser River Sediment Budget Analysis Final Report, prepared for Fraser River Estuary Management Program. 28 p. + 20 diagrams. Ollerhead, J., van Proosdij, D., and Davidson-Arnott, R. G. D. 1999. Ice as a mechanism for contributing sediments to the surface of a macro-tidal saltmarsh, Bay of Fundy. Proceedings of the 1999 Canadian Coastal Conference, Victoria, B.C. 1: 359-370. Orson, R., Ponagetou, W., and Leatherman, S. P. 1985. Response of tidal salt marshes of the United States Atlantic and Gulf coasts to rising sea levels. Journal of Coastal Research 1: 29-37. Orson, R. A., Warren, R. S, and Niering, W. A. 1998. Interpreting sea level rise and rates of vertical marsh accretion in a southern New England tidal salt marsh. Estuarine, Coastal and Shelf Science. 47: 419-429. Orson, R. A., Simpson, R. L., and Good, R. E. 1990. Rates of sediment accumulation in a tidal freshwater marsh. Journal of Sedimentary Petrology 60: 859-569. Patterson, R. T. 1990. Intertidal benthic foraminiferal biofacies on the Fraser River Delta, British Columbia: modern distribution and paleoecological importance. Micropaleontology 36: 229-244. Pethick, J. S. 1981. Long-term accretion rates on tidal salt marshes. Journal of Sedimentary Petrology 51: 571-577. Pojar, J., and MacKinnon, A. 1994. Plants of Coastal British Columbia. B.C. Ministry of Forests and Lone Pine Publishing: Vancouver. 527p. Potsma, H. 1961. Transport and accumulation of suspended matter in the Dutch Wadden Sea. Netherlands Journal of Sea Research 1: 148-190. Pott, U., and Turpin, D. 1996. Changes in atmospheric trace element deposition in the Fraser Valley, B.C., Canada from 1960 to 1993 measured by moss monitoring with Isothecium stoloniferum. Canadian Journal of Botany 74:1345-1353. 141 Public Works Canada, 1949 (revised to 1957). Fraser River System, Province of British Columbia: History of Improvements, 1871 to Date. Dominion Public Works Department, New Westminster, B.C. 66p. + 13 diagrams + appendix. Public Works Canada, 1989. Effects of dredging on Fraser River channel regime. Febuary, 1989, Project #883-578.(prepared by D. G. McLean and B. L. Tassone) 24 p. + diagrams. Public Works and Government Services, 1994. Fraser River Training Structures: Volume III Structures Maintenance Program. Draft prepared for Canadian Coast Guard. 51 p. + diagrams. Ranwell, D. S. 1964. Spartina marshes in south England II: rate and seasonal patterns of sediment accretion. Journal of Ecology 52: 54-79. Reed, D. J. 1988. Sediment dynamics and deposition in a retreating coastal salt marsh. Estuarine, Coastal and Shelf Science 26: 67-79. Reed, D. J. 1990. The impact of sea-level rise on coastal salt marshes. Progress in Physical Geography 14: 465-472. Reinhart, M. A., and Bourgeois, J. 1987. Distribution of anomalous sand at Willapa Bay, Wash.; evidence for large scale landward-directed processes. EOS, Transactions of the American Geophysical Union 68 (44): 1469. Ritchie, J. C , and McHenry, J. R. 1990. Application of radioactive fallout Cesium-137 for measuring soil erosion and sediment accumulation rates and patterns: a review. Journal of Environmental Quality 19: 215-233. Ritter, H. E., Kinsey, W. F. Ill, and Kauffman, M. E. 1972. Overbank sedimentation in the Delaware River Valley during the last 6000 years. Science 176: 374-375. Roberts, M. C. 1990. Sedimentary framework of the northern section of the Fraser River delta, British Columbia. Program with Abstracts. Geological Association of Canada, Mineralogical Association of Canada, Annual Meeting 1990 15: 112. Ross, L. J. 1979. Richmond, Child of the Fraser. Richmond'79 Centennial Society. 238p. Sandilands, R. W. 1970. The history of hydrographic surveying in British Columbia. The 4th Annual Conference of the Association of Canadian Map Libraries, Vancouver, B.C. Satake, K., Shimazaki, K., Tsuji, Y., and Ueda, K. 1996. Time and size of a giant earthquake in Cascadia inferred from Japanese tsunami records of January 1700. Nature v. 379 18: 246-249. Schreier, H., Lavkulich, L., and Hall, K. 1997. Analysis of Chapman/Gray Creek water quality. B.C. Ministry of Environment, Surry, B.C. Schropp, S.J., Lewis, F.G., Windom, H.L., Ryan, J.D., Calder, F.D., and Burney, L.C. 1990. Interpretation of metal concentrations in estuarine sediments of Florida using aluminum as a reference element. Estuaries, 13 (3) pp 227-235. 142 Scott, D. B., and Martini, I. P. 1982. Marsh foraminifera zonations in western James and Hudson Bays. Le Naturaliste Canadien 109:399-414. Skowronek, F., Sagemann, J., Stenzel, F., and Schulz., H. D. 1994. Evolution of heavy-metal profiles in River Weser Estuary sediments, Germany. Environmental Geology 24:223-232. Slotton, D. G., Suchanek, T.H., Ayers, S. M., and Reuter, J. E. 1997. Mercury bioaccumulation in Northern California: a mining legacy. Abstract # PWA062 in SET AC 18th Annual Meeting, San Francisco, California, p. 241. Smith, D. G. 1984. Vibrocoring fluvial and deltaic sediments: tips on improving penetration and recovery. Journal of Sedimentary Petrology 54: 660-663. Smith, D.G. 1987. A mini-vibrocoring system. Journal of Sedimetary Petrology 57:757-758. Standi, D. E. 1980. Fraser River Estuary Study - Water Quality: Aquatic Biota and Sediments. Ministry of Environment, Victoria B.C. Stevenson, J. C , Ward, L. G., and Kearney, M. S. 1988. Sediment transport and trapping in marsh systems: implications of tidal flux studies. Marine Geology 80: 37-59. Stumph, R. P. 1983. The process of sedimentation on the surface of a salt marsh. Estuarine, Coastal and Shelf Science 17: 495-508. Swain, L. G., and Walton, D. G. 1993. Chemistry and Toxicity of Sediments from Sloughs and Routine Monitoring Sites in the Fraser River Estuary - 1992. B.C. Environment, Lands and Parks. Tassone, B. L. 1990. Recent growth patterns of the Fraser River delta. Program with Abstracts, Geological Association of Canada, Mineralogical Association of Canada, Annual Meeting 1990 15: 15. Turner, D. V. 1995. The distribution of copper, lead, and zinc in the ribbon-marsh sediments of the North Arm of the Fraser River, Vancouver, B.C. Unpublished M. Sc. Thesis, Department of Geography, Simon Fraser University, Burnaby 149 p. Warren, R. S., and Niering, W. A. 1993. Vegetation change on a northeast tidal marsh: interaction of sea level rise and marsh accretion. Ecology 74: 96-103. Watmough, D. 1972. Shady Island: a natural history. Canada Workers' Local Initiative Program 26p. Williams, H. F. L. 1988. Sea-level Change and Delta Growth: Fraser Delta, British Columbia. Unpublished PhD. Thesis, Department of Geography, Simon Fraser University, Burnaby 256 p. 143 Williams, H. F. L., and Hamilton, T. S. 1995. Sedimentary dynamics of an eroding tidal marsh derived from stratigraphic records of 1 3 7Cs fallout, Fraser Delta, British Columbia, Canada. Journal of Coastal Research 11 (4): 1145-1156. Williams, H. F. L., and Roberts, M. C. 1989. Holocene sea-level change and delta growth: Fraser River delta, British Columbia. Canadian Journal of Earth Science 26:1657-1666. Windom, H.L., Schropp, S.J., Ryan, J.D., Smith, R.G. Jr., Burney, L.C., Lewis, F.G., and Rawlinson, C H . 1989. Natural trace metal concentrations in estuarine and coastal marine sediments of the southeastern United States. Environmental Science and Technology 23: 314-320. Wise, S. M. 1980. Caesium-137 and lead-210: a review of techniques and some applications in geomorphology. In Timescales in Geomorphology. Cullingford, R. A., Davidson, D. A., and Lewin, J. (eds.). Chichester: Wiley, 109-131. Yim, W. W.-S. 1976. Heavy metal accumulation in estuarine sediments in a historical mining of Cornwall. Marine Pollution Bulletin 7: 147-150. Personal Communicat ions John Clague, 1996, Department of Earth Science, Simon Fraser University, Burnaby, B.C. Jack Cornett, 1997, MYCORE Scientific, Ontario Robert Galois, Dec.1999, Dept. of Geography, University of British Columbia, Vancouver, B.C. Rene Giuliani, Dec. 1999, Engineering Department, Surry, B.C. Daniel Marshall, Dec. 1999, Dept. of History, University of British Columbia, Vancouver, B.C. Hans Schreier, Dec. 1997, Dept. of Soil Science, University of British Columbia, Vancouver, B.C. Michael Tarbotton, June, 1999, Trident Consultants, Vancouver, B.C. Brian Zak, Jan. 2000, Council of Forest Industries, Vancouver, B.C. 144 Aerial Photographs 1930 (1:22,000) May A 2238 75-86 A 2239 86-92 A 2240 91-96 A 2245 32-54 A 2288 28-38 1932 (1:15,000) September A 4527 29 1954 (1:12,000) July 1974 BC 1672 99-102 BC 1673 17-22, 37-42, 87-95 BC 1674 4-11,47-54, 57-63 1986 (1: 12,100) September 1994 BCC 534 214-224 BCC 535 052-056, 173-175, 209-213 (1:12,000) March-June BC 5581 218-220 BC 5588 77-95, 157-179, 236-239, 240-244 (1:25,000) July FFC 94 31,62, 93, 124 (Foto Flight Calgary) 145 A P P E N D I C E S Appendix 1: Con t ro l Points used to create A e r i a l Photographic Mosaics UTM Coordinates. Zone 10 Location 1) No.l Rd. and Granville Av., Richmond 2) No.l Rd. and Blundell Rd, Richmond 3) the railway line and Moncton St., Steveston 4) Steveston Hwy. and No.3 Rd., Richmond 5) Steveston Hwy. and No.5 Rd., Richmond 6) Westham Island Rd. and Kirkland Rd., Westham Is. 7) River Rd. and 41B St., Ladner 8) Central Av. and Cresent Dr., Ladner 9) stream and dyke, Reifel Island 10) 34 St. and 33A Av., Ladner 11) central arm and main section of CBC Catwalk, Richmond 12) 7 Av. and Garry St., Steveston 13) right angle in western Steveston Wingdam 14) west end of Woodward Training Wall 15) Steveston Hwy. and No. 6 Rd. Location of control points. 146 Easting Northing 486791.98 5445476.00 486799.16 5444778.16 486814.09 5441388.00 490036.95 5442311.09 493278.94 5442286.04 489571.95 5437035.00 492073.05 5436863.99 494940.30 5438576.95 486594.02 5439300.97 490463.65 5434579.21 485529.32 5442840.07 486010.03 5441850.96 487778.36 5440211.33 487698.01 5439725.49 494987.13 5442309.90 Appendix 2: Photographs of Core Longitudinal Sections Barber 27 148 Duck 20 1 4 9 Duck 31 1 5 0 Woodward 21 151 Lulu 33 152 Westham 29 1 5 3 Westham 30 154 Key on photographs corresponds to Figures 4.3 and 4.4. Legend: Organic Finely Coarsely Mixed Sand Silt Distorted Laminated Laminated Sand & sot 147 -° Note: measuring tape starts at 10 cm not 0 cm O Note: measuring tape starts at 10 cm not 0 cm V Note: measuring tape starts at 10 cm not 0 cm Note: measuring tape starts at 10 cm not 0 cm Appendix 3: Results of Environmental Magnetism Environmental Magnetism (Xo[xl0"6 SI/volume]) depth Barber 27 Duck 20 Duck 31 Woodward Lulu 33 Westham Westham Westham (cm) 21 30 29 15 0 663.3 769.51 247.88 794.19 909.12 1641.96 1030.47 427.46 5 1155.59 1183.28 543.64 1177.48 1426.22 2650.78 1176.76 794.69 10 1291.04 1146.16 461.33 1372.87 1638.2 3044.87 919.12 890.49 15 1873.57 1291.79 434.25 1523.29 1489.88 3339.77 1081.08 537.43 20 2077.54 1295.91 511.77 1601.93 1437.33 4395.51 1219.68 445.33 25 2159.37 1305.26 621.84 2359.42 1889.14 4309.8 1551.68 633.71 30 2703.4 986.54 766.18 2837.23 1933.14 4011.1 1906.6 1075.44 35 3408.15 681.99 957.64 3112.59 2219.95 4736.19 1599.67 1244.38 40 3425.62 561.58 1383.87 3216.15 2078.85 5712.3 2055.62 1772.46 45 2525.12 594.32 2044.52 2884.66 2546.48 6137.06 3885.57 2338.72 50 2463.39 632.38 1900.26 2795.75 3452.38 6964.36 4797.72 2565.8 55 2605.5 713.05 2063.41 3010.36 3399.77 7158.29 4558.1 2090.12 60 2341.3 837.93 2807.53 3548.75 2862.61 6548.71 5866.04 65 2545.71 1310.92 3709.25 3908.51 2429.36 6942.12 7454.77 70 2013.28 1923.25 4941.7 3333.58 2843.14 7009.83 7442.76 75 2262.98 2273.56 5829.98 3096.64 3998.28 7308.48 7459.9 80 3580.51 4487.16 6357.85 3418.96 4885.53 7512.77 7706.59 85 4522.08 4903.98 3665.19 3529.04 5743.09 7708.43 7544.75 90 4302.6 4705 2905.15 3533.91 6069.15 7361.33 7639 95 4832.01 5943.89 2536.98 3502.97 6127.53 6999.2 6679.68 100 4984.95 5368.44 2659.91 3739.64 6400.37 6942.83 6605.79 105 4628.72 3696.12 3155.89 4038.08 6267.59 7206.38 6503.4 110 3706.18 3385.29 5302.86 4454.2 5867.58 8368.78 6350.71 115 2050.29 3631.2 7672.74 4319.65 5700.29 7668.73 7498.93 120 1808.28 4335.06 7161.15 4550.57 5404.78 6893.44 10063.8 125 2314.09 5303.63 6129.02 4309.5 5393.18 5634.17 1.3450.3 130 3491.41 5972.7 6760.48 4138.32 6158.13 5642.91 9694.26 135 4039.84 5897.47 6789.12 4259.33 6471.53 5505.63 5673.7 140 5242.58 5172.45 8776.07 4282.02 6419.06 4825.82 5369.47 145 5108.4 5261.52 8800.27 4579.62 6839.99 4947.99 5557.95 150 4701.92 5102.76 6853.28 4242.64 7324.59 5066.15 5541.53 155 4623.63 4496.02 7042.44 3840.04 7498.11 4731.13 4394.75 160 4611.4 3734.15 6794.91 4167.19 7266.8 3466.77 1549.95 165 4337.89 4020.77 7325.09 4290.43 7896.64 170 4266.55 3527.55 6732.11 4288.8 7130.63 175 4667.11 3019.68 5908.58 4433.21 6017.84 180 4461.14 2559.75 3823.15 4295.8 5673.61 185 3736.09 2116.79 878.5 4090.37 5668.07 190 3574.38 1610.58 3663.08 5626.11 195 3348.24 1004.07 3882.83 6460.68 200 3612.85 3871.61 6200.74 205 3505.94 3664.49 4723.91 210 3134.62 3497.74 4980.22 215 3818.16 - 3668.16 6674.87 220 3736.87 3911.71 6593.27 155 depth Barber 27 Duck 20 Duck 31 Woodward Lulu 33 Westham Westham Westham (cm) 21 30 29 15 225 3497.73 4252.67 6003.96 230 3197.38 4512.87 5940.52 235 1581.26 4963.89 4563.95 240 4884.12 1698.48 245 4656.6 250 4058.42 156 Appendix 4: Results of Sediment Analysis (blank entries indicate missing data due to unsuccessful analysis) Barber 27 bulk density=(dry(g)/wet(cm3) L O I % = % o f dry g. depth bulk L O I % depth ( cm) bulk L O I % depth (cm) bulk L O I % (cm) density density density 0-1 0.88 6.77 45-46 1.36 3.26 90-91 1.11 3.64 1-2 0.60 6.28 46-47 1.37 2.95 91-92 1.20 3.12 2-3 1.00 6.17 47-48 1.52 92-93 1.14 2.86 3-4 1.03 6.00 48-49 1.37 3.41 93-94 1.07 1.60 4-5 0.95 6.31 49-50 1.59 3.13 94-95 1.15 2.07 5-6 1.01 6.45 50-51 1.81 2.80 95-96 1.24 2.47 6-7 1.18 6.09 51-52 1.26 2.34 96-97 1.38 2.12 7-8 0.92 6.13 52-53 1.45 2.55 97-98 1.50 2.56 8-9 1.05 6.04 53-54 1.09 2.43 98-99 1.34 2.38 9-10 1.00 5.76 54-55 1.14 2.61 99-100 1.41 3.24 10-11 1.20 5.88 55-56 1.35 2.83 100-101 1.43 3.49 11-12 1.27 6.23 56-57 1.43 2.58 101-102 1.32 4.01 12-13 1.17 5.58 57-58 1.23 2.63 102-103 1.37 3.46 13-14 0.97 5.43 58-59 2.18 2.58 103-104 1.42 3.27 14-15 1.51 4.82 59-60 1.75 2.34 104-105 1.51 3.74 15-16 1.13 5.11 60-61 1.81 1.98 105-106 1.37 3.38 16-17 1.24 4.55 61-62 1.99 1.26 106-107 1.20 3.59 17-18 1.30 4.52 62-63 1.68 1.49 107-108 1.30 3.36 18-19 1.18 4.76 63-64 1.55 1.72 108-109 1.34 2.56 19-20 1.65 4.96 64-65 1.50 1.57 109-110 1.24 2.99 20-21 1.21 5.24 65-66 1.37 1.72 110-111 1.10 3.23 21-22 1.28 4.76 66-67 1.65 2.11 111-112 1.23 2.30 22-23 1.23 5.04 67-68 1.43 2.00 112-113 0.98 1.92 23-24 1.38 5.00 68-69 1.66 2.60 113-114 1.01 1.68 24-25 1.42 4.32 69-70 1.65 2.95 114-115 1.08 1.76 25-26 1.41 4.15 70-71 1.78 2.81 115-116 1.12 1.97 26-27 1.45 3.98 71-72 1.45 3.52 116-117 1.26 2.07 27-28 1.55 3.76 72-73 1.16 3.43 117-118 1.09 2.20 28-29 2.04 3.59 73-74 1.16 3.42 118-119 1.10 2.99 29-30 1.49 3.44 74-75 1.67 3.14 119-120 1.27 3.12 30-31 1.30 3.12 75-76 1.79 3.31 120-121 0.15 3.52 31-32 1.51 3.01 76-77 1.10 2.60 121-122 1.08 3.61 32-33 1.46 3.37 77-78 1.21 2.54 122-123 1.29 2.02 33-34 1.35 2.97 78-79 1.16 2.48 123-124 1.33 2.56 34-35 1.22 2.83 79-80 1.26 2.56 124-125 0.97 3.62 35-36 1.29 2.62 80-81 1.66 2.37 125-126 1.01 2.69 36-37 1.53 3.32 81-82 1.94 2.90 126-127 1.20 2.80 37-38 1.48 2.99 82-83 1.15 2.60 127-128 1.01 2.62 38-39 1.65 3.16 83-84 1.16 2.75 128-129 1.16 2.55 39-40 2.19 2.83 84-85 1.26 2.69 129-130 0.98 2.06 40-41 1.15 2.97 85-86 1.32 3.07 130-131 0.93 2.05 41-42 1.30 2.61 86-87 1.16 3.43 131-132 0.82 2.61 42-43 1.68 3.33 87-88 1.20 3.25 132-133 1.01 1.96 43-44 1.59 3.75 88-89 1.20 3.00 133-134 1.19 2.27 44-45 1.18 2.88 89-90 1.24 3.23 134-135 1.45 2.87 157 Barber 27 depth bulk LOI% depth (cm) bulk LOI% depth (cm) bulk LOI0/ (cm) density density density 135-136 1.26 2.87 181-182 1.15 1.30 227-228 0.99 1.99 136-137 1.41 3.89 182-183 0.88 1.27 228-229 1.16 2.14 137-138 1.54 3.17 183-184 1.30 1.33 229-230 1.10 1.72 138-139 1.23 3.26 184-185 1.41 1.50 230-231 1.40 1.87 139-140 1.10 3.35 185-186 1.00 1.74 231-232 1.25 1.95 140-141 1.24 3.25 186-187 1.17 1.85 232-233 1.59 1.56 141-142 1.42 2.45 187-188 1.28 2.05 233-234 1.28 1.44 142-143 1.39 2.20 188-189 1.04 2.15 143-144 1.46 2.61 189-190 1.21 1.57 144-145 1.43 2.94 190-191 1.28 1.68 145-146 1.19 3.25 191-192 1.23 1.97 146-147 1.42 3.15 192-193 1.23 1.53 147-148 1.37 3.34 193-194 0.93 1.53 148-149 1.49 2.72 194-195 1.06 1.48 149-150 1.40 2.60 195-196 1.20 1.96 150-151 1.51 2.48 196-197 1.30 1.89 151-152 1.37 2.53 197-198 1.40 1.85 152-153 1.40 2.16 198-199 1.33 1.74 153-154 1.40 2.59 199-200 1.14 2.14 154-155 1.43 2.80 200-201 1.26 2.60 155-156 1.44 2.81 201-202 1.30 2.27 156-157 1.44 3.34 202-203 1.51 1.97 157-158 1.43 3.58 203-204 1.27 1.60 158-159 1.27 3.28 204-205 1.52 1.63 159-160 1.38 2.84 205-206 1.36 3.36 160-161 1.41 3.25 206-207 1.26 1.28 161-162 1.40 3.65 207-208 1.21 1.46 162-163 1.21 2.95 208-209 1.39 1.34 163-164 1.26 2.63 209-210 1.18 1.20 164-165 1.02 3.30 210-211 1.25 1.52 165-166 1.33 2.58 211-212 1.22 1.81 166-167 1.37 2.96 212-213 1.20 2.29 167-168 1.13 3.42 213-214 1.14 2.17 168-169 1.15 3.75 214-215 1.22 1.92 169-170 1.17 3.34 215-216 1.26 2.20 170-171 1.18 3.20 216-217 1.42 171-172 1.34 2.15 217-218 1.25 3.19 172-173 0.77 1.71 218-219 1.32 2.34 173-174 1.27 1.99 219-220 1.12 2.00 174-175 0.99 1.33 220-221 1.12 2.31 175-176 0.86 1.35 221-222 1.12 2.11 176-177 0.94 1.09 222-223 1.03 1.74 177-178 0.88 0.96 223-224 1.30 1.85 178-179 0.92 1.06 224-225 1.02 1.77 179-180 1.05 1.19 225-226 1.07 1.66 180-181 1.03 1.31 226-227 1.22 1.63 158 Duck 31 bulk density=(dry(g)/wet(cm3) LOI%=%ofdryg. depth bulk LOI% depth (cm) density (cm) 0-2 0.33 13.99 60-62 2-4 0.38 10.86 62-64 4-6 0.34 9.69 64-66 6-8 0.48 9.06 66-68 8-10 0.57 4.10 68-70 10-12 0.53 7.57 70-72 12-14 0.49 7.41 72-74 14-16 0.53 74-76 16-18 0.63 6.36 76-78 18-20 0.57 5.88 78-80 20-22 0.60 6.05 80-82 22-24 0.71 5.14 82-84 24-26 0.72 4.59 84-86 26-28 0.70 5.02 86-88 28-30 0.70 4.32 88-90 30-32 0.82 3.80 90-92 32-34 0.81 3.90 92-94 34-36 0.88 3.50 94-96 36-38 0.92 3.23 96-98 38-40 0.82 3.36 98-100 40-42 0.96 2.93 100-102 42-44 0.91 3.80 102-104 44-46 0.91 3.56 104-106 46-48 0.87 4.00 106-108 48-50 0.81 4.47 108-110 50-52 0.73 4.36 110-112 52-54 0.96 3.57 112-114 54-56 0.90 3.64 114-116 56-58 0.92 3.74 116-118 58-60 0.98 118-120 bulk LOI% depth bulk LOI% density (cm) density 0.87 3.77 120-122 1.10 1.36 0.99 3.67 122-124 1.03 1.36 1.00 3.64 124-126 0.99 1.31 1.06 2.98 126-128 0.72 1.35 0.93 3.00 128-130 0.86 1.86 1.03 3.03 130-132 1.04 2.11 1.03 3.01 132-134 0.81 1.51 1.02 2.31 134-136 0.62 1.14 1.92 136-138 0.84 2.04 1.27 1.89 138-140 0.77 1.23 0.90 2.19 140-142 0.96 1.66 0.73 1.45 142-144 0.85 1.50 0.70 1.39 144-146 0.91 1.37 0.98 1.47 146-148 0.97 1.34 0.82 1.49 148-150 0.86 1.57 0.80 1.36 150-152 0.72 1.43 0.79 1.29 152-154 0.75 2.12 0.89 1.25 154-156 0.87 2.03 0.93 1.40 156-158 0.79 1.61 0.99 1.11 158-160 0.77 1.27 0.72 1.17 160-162 0.89 1.26 0.85 1.24 162-164 0.86 1.31 0.89 1.42 164-166 1.32 1.53 0.91 1.24 166-168 0.88 1.30 1.22 2.39 168-170 0.87 2.41 1.13 1.99 170-172 0.83 3.59 0.86 1.81 172-174 0.98 2.13 1.17 1.78 174-176 0.93 1.80 1.39 2.10 176-178 0.71 2.88 1.33 1.80 178-180 0.64 180- 0.67 181.5 159 Duck 2 0 bulk density=(dry(g)/wet(cm3) LOI%=%ofdryg. depth bulk LOI% (cm) density 0-1 0.75 10.97 1-2 0.71 10.75 2-3 0.62 10.67 3-4 0.76 10.34 4-5 0.91 8.62 5-6 0.99 7.82 6-7 0.84 6.82 7-8 0.86 6.27 8-9 0.99 6.03 9-10 0.97 5.71 10-11 0.95 6.12 11-12 0.88 5.96 12-13 0.75 5.46 13-14 0.99 5.11 14-15 0.94 4.74 15-16 0.96 5.04 16-17 0.70 17-18 0.97 5.11 18-19 0.85 5.11 19-20 0.95 3.61 20-21 1.00, 3.02 21-22 1.14 2.75 22-23 1.09 2.36 23-24 1.21 2.17 24-25 1.20 3.01 25-26 1.11 2.61 26-27 0.98 3.22 27-28 1.02 2.94 28-29 1.21 2.98 29-30 1.04 3.11 30-31 1.11 3.26 31-32 1.03 3.59 32-33 1.11 3.31 33-34 1.23 2.91 34-35 0.95 3.44 35-36 1.11 3.11 36-37 0.94 3.02 37-38 0.93 3.11 38-39 1.13 2.43 39-40 1.04 1.57 40-41 1.63 2.21 41-42 0.99 3.47 42-43 1.12 3.00 43-44 1.23 3.78 44-45 1.21 4.30 45-46 1.12 3.87 46-47 1.08 3.64 47-48 1.27 3.43 depth bulk LOI% (cm) density 48-49 1.14 4.00 49-50 1.08 4.31 50-51 0.96 3.93 51-52 1.24 3.07 52-53 1.28 53-54 1.23 2.93 54-55 1.09 3.50 55-56 0.97 56-57 1.15 57-58 1.00 58-59 1.26 59-60 1.31 2.45 60-61 1.08 2.61 61-62 1.26 2.87 62-63 1.16 2.48 63-64 1.30 2.91 64-65 1.07 3.18 65-66 1.33 3.41 66-67 1.24 3.15 67-68 1.25 2.74 68-69 1.17 2.69 69-70 1.30 3.23 70-71 1.11 2.76 71-72 1.07 2.64 72-73 1.30 1.27 73-74 1.25 2.44 74-75 1.43 2.10 75-76 1.38 2.19 76-77 1.43 1.47 77-78 1.38 1.30 78-79 1.47 2.37 79-80 1.61 1.95 80-81 1.16 1.97 81-82 1.15 2.38 82-83 1.65 1.17 83-84 1.38 0.54 84-85 1.52 1.13 85-86 1.54 1.69 86-87 1.60 0.94 87-88 1.52 1.18 88-89 1.59 1.23 89-90 2.10 1.41 90-91 1.55 0.85 91-92 1.74 0.57 92-93 1.77 1.27 93-94 1.53 0.58 94-95 1.79 1.32 95-96 1.51 0.85 160 depth bulk LOI% (cm) density 96-97 1.84 0.88 97-98 1.31 0.28 98-99 1.45 0.88 99-100 1.39 0.82 100-101 1.66 0.63 101-102 1.22 1.25 102-103 1.47 1.04 103-104 1.88 0.81 104-105 1.17 0.76 105-106 1.47 0.81 106-107 1.22 0.95 107-108 1.83 0.95 108-109 1.31 0.85 109-110 1.72 0.78 110-111 1.28 0.67 111-112 1.35 0.63 112-113 1.53 0.61 113-114 1.76 0.88 114-115 1.66 0.63 115-116 1.75 0.54 116-117 1.51 0.85 117-118 1.84 0.62 118-119 1.55 0.65 119-120 1.48 0.88 120-121 1.85 0.93 121-122 1.60 0.77 122-123 1.64 1.20 123-124 1.62 1.42 124-125 1.59 0.90 125-126 2.09 1.68 126-127 1.33 2.06 127-128 1.44 1.61 128-129 1.44 1.81 129-130 1.92 1.29 130-131 1.81 1.34 131-132 1.13 1.28 132-133 1.61 1.60 133-134 1.54 1.29 134-135 1.85 1.29 135-136 1.48 0.64 136-137 1.61 1.37 137-138 1.87 1.82 138-139 1.51 1.91 139-140 1.66 2.16 140-141 1.52 1.80 141-142 1.47 1.47 142-143 1.27 1.66 143-144 1.81 0.92 Duck 2 0 bulk density=(dry(g)/wet(crn3) LOI%=%ofdryg. depth bulk LOI% depth bulk LOI% depth bulk LOI% (cm) density (cm) density (cm) density 144-145 1.52 1.51 159-160 1.79 2.27 174-175 1.03 1.66 145-146 1.84 1.13 160-161 1.37 1.52 175-176 1.42 0.60 146-147 1.56 1.31 161-162 1.36 1.55 176-177 1.16 1.16 147-148 1.62 0.93 162-163 1.56 1.28 177-178 1.01 0.97 148-149 1.55 1.23 163-164 1.44 1.42 178-180 1.40 0.88 149-150 1.70 0.89 164-165 1.26 180-182 1.43 0.60 150-151 1.54 1.44 165-166 1.53 0.90 182-184 1.08 0.58 151-152 1.46 1.84 166-167 1.48 0.88 184-186 1.81 0.91 152-153 1.71 2.51 167-168 1.67 0.60 186-188 1.58 0.89 153-154 1.37 2.25 168-169 1.32 1.19 188-190 1.78 0.89 154-155 1.53 3.31 169-170 1.14 0.88 190-192 1.63 0.66 155-156 0.99 4.14 170-171 1.32 1.03 192-194 1.46 1.17 156-157 1.23 3.44 171-172 1.40 0.81 194-196 1.20 0.88 157-158 1.33 2.97 172-173 1.33 1.62 196-198 1.10 1.16 158-159 1.87 1.84 173-174 1.19 0.85 Woodward 2 1 bulk density=(dry(g)/wet(cm3) LOI%=% of dry g. depth bulk LOI% depth bulk LOI% depth bulk LOI% (cm) density (cm) density (cm) density 0-1 1.07 5.65 25-26 1.23 4.70 50-51 1.58 4.03 1-2 1.24 5.17 26-27 1.64 51-52 1.31 4.31 2-3 1.09 4.76 27-28 1.27 4.82 52-53 1.31 4.24 3-4 1.25 4.59 28-29 1.78 4.17 53-54 1.22 4.28 4-5 1.29 4.56 29-30 1.02 4.89 54-55 1.37 4.39 5-6 1.29 5.28 30-31 1.59 3.91 55-56 1.62 3.83 6-7 0.82 31-32 1.20 3.64 56-57 1.51 4.23 7-8 1.33 5.33 32-33 1.55 3.77 57-58 1.74 3.80 8-9 0.84 6.21 33-34 1.29 3.27 58-59 1.32 3.73 9-10 1.36 5.70 34-35 1.91 3.25 59-60 1.57 3.79 10-11 1.52 4.60 35-36 0.96 3.83 60-61 1.96 3.75 11-12 1.42 4.71 36-37 1.84 3.00 61-62 1.92 3.65 12-13 1.03 4.65 37-38 1.46 3.66 62-63 1.67 3.36 13-14 1.48 4.19 38-39 1.53 3.31 63-64 2.21 2.99 14-15 1.65 4.30 39-40 1.52 4.63 64-65 1.38 2.65 15-16 1.15 4.21 40-41 1.58 4.75 65-66 1.46 3.24 16-17 1.73 3.94 41-42 1.29 4.58 66-67 1.67 2.86 17-18 1.31 3.79 42-43 1.09 4.33 67-68 1.45 2.80 18-19 1.62 4.47 43-44 1.89 3.98 68-69 1.57 3.38 19-20 1.75 3.86 44-45 1.39 4.64 69-70 1.47 3.64 20-21 1.41 3.95 45-46 1.44 3.42 70-71 1.40 3.56 21-22 1.83 4.01 46-47 1.12 3.66 71-72 1.66 3.95 22-23 1.74 3.15 47-48 1.55 3.57 72-73 1.74 4.13 23-24 1.43 2.13 48-49 1.46 3.50 73-74 1.61 3.83 24-25 1.28 3.97 49-50 1.26 4.18 74-75 1.59 3.66 161 Woodward 21 bulk density=(dry(g)/wet(cm3) LOI%=%ofdryg. depth bulk LOI% (cm) density 75-76 1.97 3.76 76-77 1.78 4.50 77-78 1.61 4.26 78-79 1.85 4.42 79-80 1.42 4.48 80-81 2.10 3.56 81-82 1.63 3.04 82-83 1.48 3.67 83-84 1.60 3.80 84-85 1.76 3.52 85-86 1.69 3.01 86-87 1.97 2.97 87-88 1.83 3.31 88-89 1.35 3.38 89-90 1.37 3.91 90-91 1.47 3.52 91-92 1.45 3.58 92-93 1.79 2.92 93-94 1.24 3.27 94-95 1.98 3.31 95-96 1.61 3.42 96-97 1.51 3.33 97-98 1.20 3.76 98-99 1.84 3.82 99-100 1.87 3.69 100-101 1.51 3.33 101-102 1.68 3.81 102-103 1.86 3.83 103-104 1.64 3.20 104-105 2.12 2.73 105-106 2.18 2.78 106-107 2.04 3.09 107-108 1.63 2.68 108-109 1.55 2.96 109-110 1.75 2.67 110-111 1.48 3.11 111-112 1.73 2.83 112-113 1.65 3.27 113-114 1.91 3.00 114-115 0.37 3.28 115-116 1.99 2.71 116-117 1.45 3.02 117-118 0.94 3.25 118-119 0.95 3.11 119-120 1.65 2.91 120-121 1.22 3.13 121-122 1.40 2.58 122-123 1.43 2.89 depth bulk LOI% (cm) density 123-124 1.57 2.87 124-125 0.91 3.07 125-126 1.53 3.62 126-127 1.30 3.12 127-128 1.50 2.85 128-129 1.39 2.80 129-130 1.84 2.81 130-131 1.83 2.60 131-132 1.29 3.02 132-133 2.06 3.01 133-134 1.61 4.17 134-135 1.59 3.19 135-136 1.69 2.87 136-137 1.85 2.99 137-138 2.00 3.23 138-139 1.14 3.21 139-140 1.78 3.19 140-141 0.99 3.48 141-142 1.26 2.46 142-143 1.71 2.25 143-144 1.68 2.60 144-145 0.82 145-146 1.07 146-147 1.19 3.53 147-148 1.55 2.35 148-149 1.82 2.40 149-150 1.77 3.47 150-151 1.51 3.98 151-152 1.64 3.90 152-153 1.65 4.11 153-154 1.62 3.64 154-155 1.55 3.35 155-156 1.55 3.26 156-157 1.72 3.43 157-158 1.75 3.48 158-159 1.22 3.67 159-160 1.82 3.66 160-161 1.69 4.10 161-162 1.55 3.80 162-163 1.24 3.21 163-164 1.56 2.81 164-165 1.69 3.03 165-166 1.93 2.86 166-167 1.76 2.80 167-168 2.34 3.45 168-169 1.65 2.55 169-170 1.52 2.93 170-171 2.08 3.32 162 depth bulk LOI% (cm) density 171-172 1.78 3.41 172-173 2.26 3.55 173-174 2.01 3.04 174-175 1.72 3.35 175-176 1.48 176-177 1.67 177-178 1.96 2.93 178-179 1.84 2.70 179-180 2.10 2.67 180-181 2.42 3.07 181-182 1.81 3.20 182-183 2.00 3.12 183-184 1.64 3.52 184-185 1.81 3.52 185-186 1.45 3.32 186-187 2.23 3.40 187-188 1.74 2.76 188-189 1.73 3.35 189-190 2.10 3.31 190-191 1.78 3.58 191-192 1.83 3.89 192-193 2.10 3.95 193-194 1.99 3.11 194-195 1.88 2.93 195-196 2.22 3.08 196-197 2.03 2.99 197-198 2.51 2.36 198-199 1.91 2.50 199-200 2.44 2.39 200-201 1.65 2.51 201-202 3.68 2.50 202-203 2.31 3.52 203-204 1.02 4.18 204-205 2.22 4.72 205-206 2.50 2.88 206-207 2.14 3.11 207-208 1.52 3.10 208-209 2.24 3.13 209-210 2.03 2.60 210-211 2.23 3.17 211-212 1.96 3.37 212-213 2.62 3.15 213-214 1.86 2.77 214-215 1.92 3.47 215-216 2.93 3.92 216-217 2.54 3.90 217-218 2.69 3.34 218-219 2.10 2.75 Woodward 21 bulk density=(dry(g)/wet(cm3) LOI%=%ofdryg. depth bulk LOI% depth bulk LOI% depth bulk LOI% (cm) density (cm) density (cm) density 219-220 1.81 3.36 223-224 2.90 3.25 227-228 2.92 2.43 220-221 2.40 3.38 224-225 2.08 2.11 228-229 2.99 2.79 221-222 2.64 2.77 225-226 1.78 2.70 229-230 3.29 1.81 222-223 2.33 3.39 226-227 2.19 2.47 Lulu 33 bulk density=(dry(g)/wet(cm3) LOI%=%ofdryg. depth bulk LOI% depth bulk LOI% depth bulk LOI% (cm) density (cm) density (cm) density 38-39 0.96 4.82 77-78 1.25 3.46 0-1 0.77 5.93 39-40 1.07 3.33 78-79 1.37 3.59 1-2 0.79 5.23 40-41 1.09 3.92 79-80 1.08 1.82 2-3 0.92 5.57 41-42 1.11 3.65 80-81 1.63 2.36 3-4 0.95 3.40 42-43 1.00 3.73 81-82 1.15 2.27 4-5 0.81 6.47 43-44 0.93 4.00 82-83 1.46 2.08 5-6 0.73 5.86 44-45 1.03 3.83 83-84 1.26 2.30 6-7 0.99 5.90 45-46 1.11 3.78 84-85 1.60 2.55 7-8 0.67 6.54 46-47 1.07 3.28 85-86 1.47 2.03 8-9 0.78 7.76 47-48 1.11 3.36 86-87 1.51 1.84 9-10 0.86 6.21 48-49 1.05 3.57 87-88 1.48 1.78 10-11 0.90 6.85 49-50 1.23 3.73 88-89 1.69 1.92 11-12 0.67 7.49 50-51 1.23 4.04 89-90 1.46 1.56 12-13 0.91 6.19 51-52 1.25 3.19 90-91 1.59 1.51 13-14 0.68 5.94 52-53 1.27 3.46 91-92 1.40 2.11 14-15 0.87 5.99 53-54 1.34 2.92 92-93 1.49 3.03 15-16 0.97 6.59 54-55 1.42 3.36 93-94 1.76 1.86 16-17 0.87 5.44 55-56 1.29 3.34 94-95 1.55 1.02 17-18 0.99 5.74 56-57 1.26 2.95 95-96 1.92 1.05 18-19 0.84 5.87 57-58 1.15 3.74 96-97 1.73 1.26 19-20 1.12 5.91 58-59 1.14 4.46 97-98 1.84 1.52 20-21 1.29 5.49 59-60 1.21 3.15 98-99 1.51 1.56 21-22 0.96 6.35 60-61 1.35 3.87 99-100 2.04 1.53 22-23 1.17 5.71 61-62 1.39 4.05 100-101 1.83 1.32 23-24 1.13 5.74 62-63 1.15 101-102 1.72 1.36 24-25 1.13 6.35 63-64 1.25 3.71 102-103 1.50 2.07 25-26 1.23 5.36 64-65 1.42 3.56 103-104 2.08 2.04 26-27 1.20 6.14 65-66 1.20 3.52 104-105 1.74 2.03 27-28 1.30 66-67 1.09 4.07 105-106 1.75 1.52 28-29 1.18 5.76 67-68 1.42 106-107 1.76 1.81 29-30 0.60 5.18 68-69 1.18 3.85 107-108 1.83 1.54 30-31 0.92 5.36 69-70 1.14 4.63 108-109 1.62 1.29 31-32 1.29 5.54 70-71 1.11 3.41 109-110 2.00 2.26 32-33 1.18 6.35 71-72 1.35 3.52 110-111 2.00 1.77 33-34 0.96 5.12 72-73 1.27 3.88 111-112 2.16 1.53 34-35 1.03 4.11 73-74 1.22 3.45 112-113 1.68 1.54 35-36 1.01 4.80 74-75 1.33 113-114 2.09 1.50 36-37 1.18 5.21 75-76 1.27 3.60 114-115 2.08 1.29 37-38 1.31 4.37 76-77 1.14 3.13 115-116 2.20 1.29 1 6 3 Lulu 33 bulk density=(dry(g)/wet(crn3) LOI%=%ofdryg. depth bulk LOI% depth bulk LOI% depth Bulk LOI% (cm) density (cm) density (cm) density 116-117 1.95 2.13 164-165 1.70 1.52 212-213 1.36 3.18 117-118 2.34 1.77 165-166 1.80 1.35 213-214 1.62 2.04 118-119 1.76 2.13 166-167 1.88 0.77 214-215 1.63 2.29 119-120 1.74 2.11 167-168 1.83 1.79 215-216 1.50 2.54 120-121 1.77 1.52 168-169 1.84 2.01 216-217 1.42 2.87 121-122 2.53 1.27 169-170 1.72 2.02 217-218 0.82 2.82 122-123 2.15 1.27 170-171 2.02 1.40 218-219 1.60 2.32 123-124 2.07 1.30 171-172 1.95 1.35 219-220 1.70 2.14 124-125 1.96 1.53 172-173 1.69 1.75 220-221 2.13 1.87 125-126 1.70 0.78 173-174 1.90 1.83 221-222 1.38 1.58 126-127 2.37 1.01 174-175 1.83 1.54 222-223 1.54 1.52 127-128 1.90 1.51 175-176 1.93 1.76 223-224 1.90 1.55 128-129 2.26 1.20 176-177 1.84 2.08 224-225 1.55 1.30 129-130 2.19 1.68 177-178 1.60 2.30 225-226 1.25 1.17 130-131 1.75 1.83 178-179 1.47 2.28 226-227 1.24 1.14 131-132 1.84 1.38 179-180 1.34 2.51 227-228 0.85 0.85 132-133 1.86 1.81 180-181 1.26 2.02 228-229 2.29 1.20 133-134 2.08 1.34 181-182 1.82 2.08 229-230 1.77 1.08 134-135 1.84 2.03 182-183 1.80 1.26 230-231 1.70 1.16 135-136 2.31 1.69 183-184 1.60 1.52 231-232 2.28 1.66 136-137 1.85 1.29 184-185 1.65 2.83 232-233 1.85 1.60 137-138 2.05 1.43 185-186 1.63 2.61 233-234 1.90 2.04 138-139 2.04 1.14 186-187 1.68 1.81 234-235 1.34 3.12 139-140 2.13 1.29 187-188 1.79 2.01 235-236 1.20 3.99 140-141 2.01 1.78 188-189 1.47 3.19 236-237 1.61 3.66 141-142 2.08 1.26 189-190 1.49 2.56 237-238 1.37 3.99 142-143 1.87 1.53 190-191 1.17 3.47 143-144 2.06 2.02 191-192 1.05 3.01 144-145 2.05 1.27 192-193 1.35 2.17 145-146 1.18 1.52 193-194 1.65 2.52 146-147 1.64 1.78 194-195 1.64 2.48 147-148 1.80 1.26 195-196 1.69 1.85 148-149 1.99 1.27 196-197 1.54 1.85 149-150 1.60 1.53 197-198 1.74 1.52 150-151 2.01 1.55 198-199 1.69 1.75 151-152 1.72 2.05 199-200 1.64 2.35 152-153 1.78 1.28 200-201 1.65 2.56 153-154 2.03 201-202 1.53 2.46 154-155 1.61 0.76 202-203 1.40 3.61 155-156 1.85 0.90 203-204 1.22 3.86 156-157 1.88 1.05 204-205 1.14 3.60 157-158 1.76 1.75 205-206 1.20 3.64 158-159 1.97 1.01 206-207 1.22 3.75 159-160 1.97 1.39 207-208 1.03 3.62 160-161 1.62 1.29 208-209 0.89 3.99 161-162 1.75 1.32 209-210 1.13 4.02 162-163 1.90 1.51 210-211 1.23 3.57 163-164 1.90 1.27 211-212 1.56 3.11 164 Westham 29 bulk density=(dry(g)/wet(cm3) LOI%=%ofdryg. depth bulk LOI% (cm) density 0-1 0.90 8.94 1-2 0.97 7.38 2-3 0.85 6.94 3-4 0.84 7.17 4-5 0.88 4.69 5-6 0.77 4.65 6-7 0.80 8.33 7-8 0.74 6.97 8-9 0.84 6.96 9-10 0.65 7.57 10-11 0.74 6.43 11-12 0.71 7.77 12-13 0.62 8.96 13-14 0.71 8.77 14-15 0.71 8.33 15-16 0.67 7.29 16-17 0.70 7.69 17-18 0.77 7.23 18-19 0.84 6.28 19-20 0.79 7.29 20-21 0.91 6.36 21-22 0.93 5.60 22-23 0.82 5.85 23-24 0.83 6.85 24-25 0.84 7.52 25-26 0.99 5.26 26-27 1.03 5.57 27-28 0.91 5.84 28-29 1.06 5.78 29-30 0.88 6.52 30-31 0.92 6.27 31-32 1.05 6.34 32-33 1.09 5.87 33-34 1.04 6.00 34-35 1.12 5.62 35-36 1.00 5.31 36-37 1.04 5.59 37-38 1.19 4.76 38-39 0.93 5.32 39-40 1.05 5.11 40-41 1.15 5.31 41-42 1.02 42-43 1.13 4.56 43-44 1.41 3.21 44-45 1.21 3.07 45-46 1.51 3.27 46-47 1.20 4.75 47-48 1.51 3.05 depth bulk LOI% (cm) density 48-49 1.38 3.79 49-50 1.43 3.27 50-51 1.06 3.31 51-52 1.42 4.09 52-53 1.25 6.33 53-54 1.31 4.56 54-55 1.23 4.51 55-56 1.44 3.83 56-57 1.46 3.29 57-58 1.85 2.63 58-59 1.79 3.02 59-60 1.92 3.28 60-61 1.34 2.82 61-62 1.40 3.28 62-63 1.41 2.78 63-64 1.04 2.87 64-65 1.61 2.82 65-66 1.54 2.06 66-67 1.41 1.78 67-68 1.75 1.79 68-69 1.94 2.28 69-70 1.77 2.49 70-71 1.26 1.81 71-72 1.32 2.07 72-73 1.80 1.80 73-74 1.35 1.44 74-75 1.55 1.54 75-76 1.90 1.46 76-77 1.70 1.22 77-78 2.00 1.86 78-79 1.87 1.41 79-80 2.18 • 1.35 80-81 1.58 1.51 81-82 2.05 2.01 82-83 1.80 2.29 83-84 1.86 1.77 84-85 2.14 1.24 85-86 1.69 1.11 86-87 1.64 1.79 87-88 1.62 1.55 88-89 1.82 1.50 89-90 2.02 2.05 90-91 1.82 1.76 91-92 1.81 2.32 92-93 1.55 2.54 93-94 1.56 2.30 94-95 1.64 3.02 95-96 1.67 2.83 depth bulk LOI% (cm) density 96- 97 1.59 2.76 97- 98 1.55 3.05 98- 99 1.50 2.27 99- 100 1.54 2.51 100- 101 0.84 2.76 101- 102 1.23 1.78 102- 103 1.08 103- 104 1.20 1.15 104- 105 1.37 2.28 105- 106 1.39 2.54 106- 107 1.32 2.28 107- 108 1.55 2.03 108- 109 1.32 2.03 109- 110 1.18 2.25 110- 111 1.49 2.48 111- 112 1.53 2.24 112- 113 1.61 2.71 113- 114 1.64 2.26 114- 115 1.65 1.53 115- 116 1.82 1.98 116- 117 1.72 1.76 117- 118 1.75 1.50 118- 119 1.68 1.77 119- 120 1.61 2.05 120- 121 1.64 1.79 121- 122 1.75 1.75 122- 123 1.99 2.02 123- 124 1.89 1.76 124- 125 1.50 2.04 125- 126 1.92 1.56 126- 127 1.60 2.05 127- 128 1.37 128- 129 1.25 1.33 129- 130 1.46 1.25 130- 131 1.44 1.68 131- 132 1.46 1.08 132- 133 1.33 1.48 133- 134 1.54 1.13 134- 135 1.89 3.01 135- 136 0.08 2.65 136- 137 1.54 1.19 137- 138 1.61 1.29 138- 139 1.66 1.39 139- 140 1.86 3.30 140- 141 1.89 3.50 141- 142 1.25 1.76 142- 143 1.37 1.57 143- 144 1.41 1.12 165 Westham 29 bulk density=(dry(g)/wet(crn3) LOI%=%ofdryg. depth bulk LOI% (cm) density 144- 145 1.36 1.39 145- 146 1.54 1.31 146- 147 0.95 1.47 147- 148 1.10 1.31 depth bulk LOI% (cm) density 148- 149 1.25 1.24 149- 150 1.88 1.49 150- 151 1.61 1.28 151- 152 1.83 2.03 depth bulk LOI% (cm) density 152- 153 1.61 1.98 153- 154 1.23 1.62 154- 155 1.83 2.01 Westham 30 bulk density=(dry(g)/wet(cm3) LOI%=% of dry g. depth bulk LOI% depth bulk LOI% depth bulk LOI% (cm) density (cm) density (cm) density 0-1 0.87 3.80 38-39 1.06 3.17 76-77 1.59 1.82 1-2 0.76 4.51 39-40 1.50 2.20 77-78 1.99 1.79 2-3 0.96 40-41 1.20 3.72 78-79 1.71 1.78 3-4 0.96 4.65 41-42 1.10 3.20 79-80 1.55 2.04 4-5 0.95 3.73 42-43 1.15 3.27 80-81 1.75 2.31 5-6 0.92 4.01 43-44 1.24 3.12 81-82 1.32 2.43 6-7 0.92 4.36 44-45 1.07 2.59 82-83 1.93 1.92 7-8 . 1.00 4.41 45-46 1.30 3.42 83-84 1.58 1.98 8-9 0.86 4.76 46-47 1.37 2.66 84-85 1.89 2.13 9-10 0.92 4.72 47-48 1.47 2.49 85-86 1.36 2.26 10-11 0.89 5.25 48-49 1.26 2.55 86-87 1.90 2.11 11-12 1.14 4.88 49-50 1.67 2.59 87-88 1.66 12-13 0.93 3.93 50-51 1.28 88-89 1.64 1.98 13-14 0.89 4.44 51-52 1.71 2.40 89-90 1.57 1.11 14-15 0.77 5.30 52-53 1.46 2.21 90-91 1.65 1.37 15-16 0.96 5.63 53-54 1.66 2.04 91-92 1.31 2.29 16-17 1.01 4.23 54-55 2.06 2.12 92-93 1.61 2.04 17-18 0.98 3.52 55-56 1.59 2.11 93-94 1.82 1.65 18-19 1.20 3.34 56-57 1.66 1.99 94-95 1.42 2.23 19-20 1.02 3.73 57-58 1.84 1.60 95-96 1.47 2.47 20-21 1.14 4.26 58-59 1.75 0.84 96-97 1.66 0.92 21-22 1.11 4.08 59-60 2.08 1.56 97-98 1.75 2.17 22-23 1.21 4.09' > 60-61 1.70 1.15 98-99 1.52 1.91 23-24 1.00 3.65 61-62 1.57 1.69 99-100 1.61 1.34 24-25 1.26 3.64 62-63 2.06 1.26 100-101 1.72 2.10 25-26 0.97 3.35 63-64 1.55 2.23 101-102 1.53 1.70 26-27 1.02 3.45 64-65 1.52 2.48 102-103 1.72 1.40 27-28 1.25 2.63 65-66 1.81 1.97 103-104 1.44 2.02 28-29 1.01 3.97 66-67 1.62 2.13 104-105 1.61 2.02 29-30 1.09 3.51 67-68 1.74 2.23 105-106 1.56 0.74 30-31 1.02 3.69 68-69 1.77 1.99 106-107 1.69 0.88 31-32 1.01 3.91 69-70 1.70 2.29 107-108 1.45 0.88 32-33 1.07 3.17 70-71 1.73 2.12 108-109 1.69 1.63 33-34 1.10 3.31 71-72 1.59 1.87 109-110 1.84 1.89 34-35 1.06 4.29 72-73 1.71 1.50 110-111 1.63 1.48 35-36 0.88 4.46 73-74 2.06 1.69 111-112 1.43 1.40 36-37 1.05 ' 3.81 74-75 1.85 1.86 112-113 1.61 0.96 37-38 1.14 3.65 75-76 1.95 1.57 113-114 1.83 1.46 166 Westham 30 bulk density=(dry(g)/wet(cm3) LOI%=%ofdryg. depth bulk LOI% depth bulk LOI% depth bulk LOI% (cm) density (cm) density (cm) density 114-115 1.64 1.21 130-131 1.33 2.33 146-147 1.05 2.61 115-116 1.97 1.38 131-132 1.46 1.78 147-148 1.50 1.79 116-117 1.72 1.42 132-133 1.33 2.30 148-149 0.97 0.92 117-118 1.64 1.30 133-134 1.28 3.09 149-150 1.68 1.52 118-119 1.65 0.83 134-135 1.25 3.79 150-151 1.61 1.31 119-120 1.46 0.79 135-136 1.58 3.61 151-152 1.29 1.37 120-121 1.49 2.47 136-137 1.15 2.22 152-153 1.38 1.53 121-122 1.47 2.01 137-138 1.20 4.36 153-154 0.91 1.07 122-123 1.21 1.47 138-139 1.18 4.06 154-155 0.85 1.79 123-124 1.61 1.63 139-140 1.11 3.94 155-156 1.06 1.36 124-125 1.83 0.79 140-141 1.03 3.35 156-157 1.22 1.63 125-126 1.21 1.43 141-142 1.28 2.88 157-158 0.88 1.45 126-127 1.37 1.61 142-143 1.22 2.95 158-159 1.29 1.27 127-128 1.76 2.14 143-144 0.97 2.88 159- 0.45 1.74 128-129 1.36 2.21 144-145 1.38 4.11 160.03 129-130 1.87 2.10 145-146 1.23 3.31 167 Sediment Texture Analysis Barber 27 Percent in each size category Barber 27 Percent in each size category depth %>250 %250-%180- %125- %60- %<4 nm depth %>250 %250-%180- %125- %60- %<4 (cm) um 180um 125um 60um 4um (cm) um 180um 125um 60um 4um um 0 -4 1.10 0.30 0.20 0.20 69.80 28.40 160 -164 0.74 0.27 6.66 15.19 66.87 9.42 4 -8 2.30 0.04 0.21 0.85 73.10 23.50 164 -168 0.00 0.00 1.13 21.01 69.83 6.42 8 - 12 1.20 0.00 0.10 -0.10 71.30 27.50 168- 170 0.73 0.00 4.80 9.74 74.58 10.21 12 - 16 0.90 0.19 0.05 0.85 74.90 23.40 170- 172 14.44 15.69 8.52 7.16 49.31 6.91 16 - 20 0.00 0.29 0.53 1.75 71.00 26.30 172 -174 14.75 15.32 9.23 15.26 40.03 4.55 20 - 24 5.60 0.00 -0.86 -0.10 69.40 26.70 174 -176 2.30 3.17 15.11 46.17 30.33 3.10 24 - 28 7.80 0.00 0.69 3.25 68.70 19.10 176 -180 1.32 1.09 15.16 47.89 30.18 3.51 28 - 32 0.00 1.65 0.83 7.95 75.70 15.30 180- 184 0.65 0.34 11.70 55.73 28.04 2.50 32 - 34 0.00 0.00 1.95 8.75 76.10 12.10 184 -188 0.33 0.00 5.03 48.14 40.37 5.15 34 - 36 0.00 0.00 2.05 12.25 71.20 13.50 188 -192 0.99 0.00 1.04 36.51 45.18 15.68 36 - 40 1.60 2.61 3.24 12.60 68.70 10.90 192 -196 0.67 0.00 3.15 49.65 39.03 6.98 40 - 44 0.00 0.60 2.28 18.40 71.70 6.70 196- 200 0.33 0.00 1.00 35.26 50.01 12.40 44 - 48 0.40 0.00 0.87 10.45 79.30 8.90 200- 202 2.65 1.18 8.23 21.60 51.62 13.53 48 - 50 0.10 1.33 3.41 16.95 69.30 8.50 202 -204 4.65 20.26 47.64 15.82 50 - 56 0.00 1.71 6.44 25.90 55.80 8.70 204 -206 12.00 14.33 10.00 16.02 35.39 14.25 56 - 60 0.00 5.59 22.76 21.50 48.95 4.74 206 -208 22.00 27.00 13.00 8.11 17.15 9.25 60 - 66 0.00 7.07 8.21 38.85 46.40 2.70 208 -210 22.52 29.80 14.57 9.80 14.74 7.58 66 - 70 0.00 1.49 27.99 30.09 39.20 1.85 210- 212 17.88 17.22 7.95 11.68 33.04 10.90 70 - 74 0.31 0.00 3.28 15.90 69.51 8.14 212 -214 13.67 10.33 5.00 9.89 39.29 21.48 74 - 78 0.00 0.00 9.40 16.09 64.53 8.27 214- 216 12.00 7.33 4.33 10.01 42.71 21.95 78 - 82 0.99 0.65 3.99 21.93 66.28 7.15 216 -218 3.67 2.67 2.33 8.31 53.43 29.59 82 - 86 0.33 0.00 2.94 14.87 71.40 9.06 218 -220 1.33 1.00 1.33 23.79 41.04 31.50 86 - 90 0.36 0.54 2.69 14.83 71.86 8.99 220- 222 1.03 0.69 1.38 36.56 42.81 16.84 90 - 94 0.00 0.00 2.08 14.44 74.90 7.56 222 -224 0.67 1.00 1.00 44.29 42.28 9.09 94 - 98 0.31 0.00 8.16 35.41 52.08 3.08 224 -226 0.66 0.33 1.32 55.78 29.21 12.70 98 - 102 0.00 0.00 7.16 21.23 64.69 5.58 226- 228 0.67 1.00 0.67 41.56 44.97 10.80 102- 106 1.04 1.52 3.69 11.09 76.59 7.11 228 -230 0.33 0.67 1.00 35.31 47.43 14.26 106 -110 0.00 0.38 11.49 16.44 64.28 6.26 230 -232 0.67 0.67 1.33 41.90 54.13 0.97 110- 114 0.00 2.44 7.98 22.40 58.95 8.24 232 -236 1.00 0.33 3.33 39.05 51.02 4.94 114 -120 0.00 0.36 3.92 33.03 57.06 4.54 120 -124 1.37 0.45 5.61 13.28 70.49 9.72 124 -128 0.36 0.00 5.89 20.96 64.73 6.65 128 -132 0.35 0.40 3.33 18.91 71.52 5.06 132 -136 0.33 0.33 9.00 27.44 55.95 6.28 136- 140 0.00 0.74 14.91 26.27 50.63 5.97 140 -144 0.99 1.00 8.10 19.67 62.14 7.60 144 -148 1.02 0.39 6.25 13.32 71.63 6.89 148 -152 0.71 0.47 7.86 17.96 70.30 2.45 152 -156 1.06 0.71 8.16 19.29 63.88 6.55 156 -160 0.36 0.00 5.98 8.88 74.56 10.00 168 Duck 20 Percent in each size category Duck 20 Percent in each size category depth %>250 %250- %180- %125- %60- %<4 nm depth %>250 %250- %180- %125- %60- %<4 (cm) nm 180um 125ixm 60p:m 4um (cm) nm 180nm 125nm 60nm 4nm n m 0 - 4 2.40 1.60 1.20 0.28 67.94 24.98 4 - 8 3.64 2.27 0.91 0.81 67.21 22.43 8 - 12 4.09 3.64 2.27 1.13 66.33 19.36 12 - 16 5.00 0.91 1.36 2.77 73.17 16.33 16 - 20 2.73 0.91 1.36 2.23 68.71 21.79 20 - 24 3.64 1.36 0.45 2.61 72.12 18.45 24 - 28 1.82 1.82 6.36 3.58 70.78 12.92 28 - 32 2.73 2.27 5.45 3.25 68.69 15.79 32 -36 2.73 2.27 4.55 7.38 73.97 5.47 36 - 40 3.18 1.82 4.09 1.15 73.01 14.02 40 -44 3.18 6.36 14.09 44 -48 3.64 1.36 3.18 6.21 71.64 12.15 48 - 52 2.73 2.73 8.64 52 - 56 2.27 0.91 7.27 8.64 66.76 10.97 56 - 60 3.64 0.91 3.18 7.41 67.55 13.23 60 - 64 4.55 0.91 4.55 4.15 66.33 15.89 64 - 68 4.07 0.58 3.49 12.20 64.88 10.71 68 - 72 2.27 1.36 4.55 4.93 71.55 13.07 72 - 76 3.64 1.36 2.27 5.61 71.10 13.75 76 - 76 4.10 0.48 29.16 1.98 43.55 18.33 76 - 80 3.64 11.36 15.91 80 - 80 5.79 31.10 23.48 12.73 17.06 8.92 80 - 84 4.00 25.00 23.33 84 - 84 4.19 13.69 17.22 19.70 33.90 10.42 84 88 - 88 - 92 4.80 7.00 14.00 12.67 17.60 25.00 92 -96 16.00 16.33 8.00 19.95 34.45 2.27 96 -98 25.22 38.06 17.31 98 - 100 15.55 44.37 26.11 6.64 4.80 1.40 100 - 104 7.91 43.11 34.82 104 - 106 5.05 44.40 34.56 106 - 108 4.25 32.63 43.55 13.38 4.17 1.57 108 - 110 6.43 43.71 32.14 110 - 112 11.26 46.98 20.76 13.24 4.85 2.26 112 - 114 8.62 39.54 29.69 114 - 116 21.08 25.04 13.89 23.74 12.40 2.97 116 - 120 18.59 32.50 28.28 120 - 124 18.53 25.59 32.35 14.80 7.93 0.65 124 - 126 9.63 17.61 25.08 14.54 29.79 3.18 126 - 128 4.97 11.92 16.56 128 -130 3.86 15.70 26.09 130- 132 3.41 15.28 10.33 27.12 35.92 7.34 132- 134 3.33 15.00 27.33 134- 136 1.84 8.66 10.05 43.42 29.72 5.78 136- 138 0.99 5.30 15.23 138 - 140 1.77 5.60 2.55 18.14 60.34 10.12 140- 142 1.67 6.00 21.67 27.79 142 -144 2.87 9.46 11.22 23.67 45.42 7.37 144 -148 5.56 13.89 33.95 15.39 25.35 4.93 148 -152 3.86 11.36 28.18 25.86 26.88 3.85 152 -156 3.09 5.23 8.55 11.69 58.11 13.10 156 - 160 0.86 1.14 4.29 7.36 70.14 15.65 160- 164 17.73 15.60 12.77 6.20 39.29 8.41 164 - 168 21.70 23.42 28.16 11.12 12.69 2.91 168- 172 24.44 16.89 29.04 19.08 8.36 2.19 172 - 176 10.22 14.70 37.22 24.58 11.42 2.34 176 -178 12.81 17.19 34.84 23.61 7.56 2.27 178 - 180 12.98 16.81 14.90 38.82 13.24 2.36 180- 182 14.63 17.31 32.84 22.70 8.77 2.26 182- 184 21.35 20.76 31.87 184 -186 13.46 13.46 27.52 27.39 14.44 2.20 186 -188 11.98 11.08 22.46 188 -192 11.38 10.18 19.16 31.41 23.12 3.85 192 -196 12.13 9.47 18.05 29.91 26.25 3.90 196 -198 10.26 8.21 14.37 34.40 29.14 3.91 169 Duck 31 Percent in each size category Duck 31 Percent in each size category depth %>250 %250- %180- %125- %60- %<4 nm depth %>250 %250- %180- %125- %60- %<4 (cm) um 180|xm 125um 60um 4um (cm) um 180um 125um 60um 4um um 0 -4 2.39 1.44 0.96 1.48 4 - 8 5.42 2.46 2.46 0.71 8 - 12 2.30 4.93 5.59 1.53 12 - 16 2.55 1.09 1.46 0.74 16 - 20 4.14 1.13 1.13 2.98 20 -24 1.36 1.36 1.36 3.57 24 - 28 2.77 1.38 1.04 5.58 28 - 32 2.45 2.10 1.75 4.09 32 - 36 2.00 1.33 1.00 3.34 36 -40 2.00 1.67 1.00 7.08 40 -44 2.67 2.00 1.33 8.18 44 -48 2.00 2.00 1.00 6.37 48 - 52 1.79 1.43 1.08 5.99 52 - 56 2.33 3.33 1.67 10.08 56 - 60 2.33 1.33 1.33 60 - 64 1.67 0.67 1.00 11.55 64 - 68 1.00 1.33 1.00 68 - 72 2.67 2.00 1.33 4.25 72 - 76 3.00 5.00 2.00 6.53 76 - 78 13.33 23.00 11.67 78 - 80 7.16 27.32 0.51 3.79 80 - 82 20.67 34.92 9.50 82 - 84 16.70 51.38 4.15 7.14 84 - 84 18.44 48.23 17.97 84 - 88 2.35 88 -90 19.61 46.77 18.97 90 - 92 17.05 53.92 9.67 7.19 92 - 96 16.70 55.16 18.76 96 - 100 14.63 55.49 17.68 100 - 102 12.85 54.15 20.16 102 - 104 13.98 56.99 19.35 3.43 104 - 108 12.07 48.11 21.08 108 - 112 5.73 16.36 7.98 5.43 112 - 116 2.00 13.00 12.50 11.63 116 - 120 3.50 16.25 19.75 17.41 120 - 122 3.40 30.40 32.80 15.04 122 - 124 1.52 26.45 13.05 25.32 124 - 126 2.17 19.67 41.67 126 - 128 0.78 11.94 14.74 39.71 128 - 130 2.00 8.00 22.25 27.17 58.36 32.51 130 -132 0.00 57.51 30.94 132 -136 1.76 49.73 33.61 136- 140 1.20 68.79 22.44 140 -144 2.00 63.79 23.46 144 -148 1.40 69.02 21.31 148 -152 1.20 68.79 18.71 152 -156 0.80 65.45 21.36 156- 160 1.00 70.98 18.35 160- 164 0.80 75.94 11.32 164 -168 1.00 69.84 14.97 168 -172 1.00 70.45 15.51 172 -176 1.33 69.32 18.24 176- 180 3.00 67.56 14.03 180- 184 1.71 71.85 11.27 73.13 14.96 69.34 11.14 48.11 10.73 15.83 3.15 7.54 0.99 8.53 2.48 6.62 1.42 46.20 3.18 53.65 5.22 38.92 3.92 16.56 28.07 4.09 27.65 4.59 5.50 4.13 13.97 68.55 7.13 7.91 27.69 28.47 33.29 10.60 31.20 23.72 29.15 3.74 15.25 32.75 18.19 26.43 3.88 26.00 41.00 12.06 15.84 2.10 15.40 25.00 57.60 7.60 26.00 26.32 33.96 3.92 8.60 30.20 27.29 29.36 2.55 5.89 33.28 35.54 21.74 1.95 6.00 27.00 65.20 2.67 13.33 32.19 41.70 6.78 2.00 11.67 38.02 41.66 5.00 3.67 17.00 21.36 41.03 11.27 1.71 4.45 3.86 57.96 27.90 170 Woodward 21 Percent in each size category Woodward 21 Percent in each size category depth %>250 %250- %180- %125- %60- %<4 nm depth %>250 %250- %180- %125- %60- %<4 (cm) um 180um 125um 60um 4um (cm) um 180um 125um 60um 4um um 0 - 4 0.00 2.54 1.69 4.33 72.15 17.59 4 - 8 0.00 0.83 1.25 3.18 74.79 18.29 8 - 12 0.45 1.79 1.35 2.39 69.73 23.40 12 - 16 4.44 2.22 1.78 1.23 68.25 25.18 16 - 20 1.77 2.65 2.21 2.53 68.20 23.08 20 - 24 2.11 5.06 4.64 2.17 66.06 18.69 24 - 28 3.75 9.58 7.08 3.15 57.02 18.59 28 - 32 1.07 1.79 1.43 1.34 76.38 17.99 32 -36 1.29 2.15 2.15 1.71 72.37 20.77 36 -40 1.30 2.61 1.74 2.55 74.35 17.45 40 -44 0.85 1.69 1.69 5.27 70.29 20.21 44 - 48 0.45 0.91 1.36 2.59 72.12 21.20 48 - 52 1.24 1.24 2.07 8.97 70.24 16.22 52 - 56 0.00 1.23 1.64 8.88 68.95 17.67 56 - 60 0.41 1.22 3.27 9.29 70.22 14.36 60 - 64 0.00 1.25 2.92 7.79 72.01 15.20 64 - 68 0.36 1.46 7.66 27.92 51.53 10.32 68 - 72 0.37 1.11 2.22 14.20 71.56 10.17 72 - 76 0.43 0.86 1.72 12.84 74.63 9.08 76 - 80 0.00 1.25 2.08 8.03 83.62 6.27 80 - 84 0.00 0.81 1.63 14.22 76.53 6.00 84 - 88 0.43 1.72 1.29 4.97 85.72 6.72 88 - 92 1.26 1.68 3.36 22.89 65.72 6.77 92 - 96 0.43 0.85 1.28 9.62 73.56 12.98 96 - 100 0.43 1.30 3.48 13.24 67.51 14.47 100 - 104 0.41 0.81 3.25 14.21 69.24 11.27 104 - 108 0.82 0.82 2.06 9.24 73.96 13.10 108 - 112 0.38 0.38 1.15 7.69 77.46 12.16 112 - 116 0.45 0.90 1.80 10.17 72.06 13.72 116 - 120 0.90 0.45 0.90 5.64 78.42 13.23 120 - 124 0.43 0.43 1.72 9.89 77.10 9.99 124 - 128 0.41 0.41 1.24 12.20 76.42 9.74 128 - 132 0.45 0.45 1.36 132 - 136 0.85 0.43 1.71 8.98 79.58 8.02 136 - 140 0.41 0.82 2.87 10.21 76.18 9.92 140 - 144 0.43 0.87 1.74 13.77 72.91 10.28 144 - 148 0.87 0.43 1.74 18.53 66.70 11.29 148 - 152 0.84 0.84 0.84 9.50 79.69 8.71 152 - 156 0.44 0.44 0.88 0.29 85.47 12.48 156 - 160 0.00 0.45 0.89 4.24 83.66 10.75 160 - 164 0.45 0.45 1.36 2.86 80.19 15.58 164- 168 0.45 0.45 1.36 4.30 78.38 15.05 168 - 172 0.43 0.43 0.43 8.53 81.89 8.72 172 - 174 0.41 0.41 0.83 174 - 176 0.00 0.00 1.39 3.86 86.86 6.93 176- 178 0.85 0.42 1.27 178 - 180 0.00 0.00 0.40 4.97 88.02 5.96 180 - 184 0.00 0.36 0.72 184- 188 0.00 0.88 0.44 1.56 87.92 7.89 188 - 192 0.00 0.44 0.88 2.15 90.65 4.99 192 - 196 0.00 0.94 0.47 2.73 86.80 8.10 196- 200 11.98 7.78 1.20 3.73 64.64 7.68 200- 204 18.79 10.74 5.37 3.53 55.70 4.87 204 - 208 1.60 1.20 0.80 6.40 208 - 212 1.64 2.46 4.92 6.07 78.89 5.62 212 - 216 1.14 4.56 20.15 9.17 58.71 5.50 216- 220 0.41 1.64 4.51 6.70 82.05 4.28 220 - 224 0.83 0.42 2.92 10.49 80.08 5.68 224 - 228 0.28 0.28 6.82 49.09 40.91 0.91 228 - 232 0.00 0.30 2.98 36.90 58.17 0.77 171 Lulu 33 Percent in each size category depth %>250 %250-%180- %125- %60- %<4 (cm) um 180um 125um 60um 4um nm 0 -4 0.45 0.91 0.45 0.78 82.97 13.98 4 - 8 0.00 1.36 0.91 1.36 79.37 16.54 8 - 12 0.00 0.89 0.45 1.43 73.94 20.16 12 - 16 0.00 0.87 0.87 2.14 73.92 21.33 16 - 20 0.00 0.44 0.88 0.87 70.03 25.56 20 - 24 0.00 0.00 0.43 0.99 75.94 22.21 24 - 28 0.00 1.35 0.90 2.89 74.91 18.61 28 - 32 0.00 0.00 0.45 1.54 75.89 19.00 32 - 36 0.00 0.00 0.45 - 2.26 77.76 18.16 36 - 40 0.00 0.46 0.46 2.47 74.76 21.40 40 - 44 0.00 0.90 0.90 0.29 66.67 30.79 44 - 48 0.00 0.46 0.92 1.66 72.40 23.64 48 - 52 0.45 0.45 0.45 1.68 74.37 22.59 52 - 56 0.46 0.46 0.91 1.96 74.81 21.40 56 - 60 0.45 0.45 0.89 2.27 70.54 25.85 60 - 64 0.46 0.91 0.46 1.95 69.97 25.80 64 - 68 0.46 0.46 0.92 1.68 73.47 23.47 68 - 72 0.45 0.45 0.90 0.29 72.67 25.24 72 - 76 0.46 0.46 0.46 2.06 74.40 21.69 76 - 80 0.91 0.91 1.37 2.21 73.74 19.95 80 - 84 0.87 1.74 0.87 2.92 79.76 14.71 84 - 88 1.34 1.34 1.34 6.18 76.26 12.65 88 - 92 5.83 7.08 5.00 9.86 62.08 8.89 92 - 96 13.00 17.33 11.00 8.99 42.63 6.38 96 - 100 10.25 16.17 15.03 11.73 40.31 6.04 100 - 104 27.92 15.04 14.56 9.84 26.45 5.23 104 - 108 8.54 12.04 12.04 11.89 46.02 8.50 108 - 112 15.81 10.68 5.13 10.19 50.01 7.75 112 - 116 30.77 17.03 5.22 8.95 30.83 6.10 116- 120 28.05 16.10 5.85 7.87 35.95 5.69 120- 124 28.99 16.85 7.42 8.27 33.37 5.09 124 - 128 46.73 21.43 10.20 3.54 14.81 3.09 128 - 132 12.11 20.10 35.23 16.65 12.00 3.18 132 - 136 4.62 14.01 39.65 24.82 13.56 3.34 136 - 140 3.94 12.64 42.20 25.23 11.72 3.61 140 - 144 2.40 13.36 44.18 26.12 9.17 3.75 144 - 148 2.33 15.64 33.11 31.05 12.17 4.70 148 - 152 1.33 7.00 24.33 44.13 18.66 3.37 152 - 156 3.11 5.25 15.37 37.41 32.63 5.84 156 - 160 1.35 4.28 19.82 43.27 20.61 4.59 Lulu 33 Percent in each size category depth %>250 %250-%180- %125- %60- %<4 (cm) um 180um 125um 60um 4um nm 160- 164 1.00 4.75 20.50 45.25 21.46 6.04 164 - 168 0.78 5.70 24.61 40.69 22.91 4.79 168 - 172 0.78 6.49 27.27 35.02 21.98 6.90 172 - 176 0.48 6.05 24.70 47.63 15.58 4.83 176- 180 0.76 3.78 12.09 23.91 50.75 9.23 180- 184 0.97 2.26 7.74 22.35 56.86 9.49 184 - 188 1.08 2.52 5.76 21.48 59.43 10.10 188- 192 5.49 5.86 6.59 16.41 53.74 11.90 192 - 196 6.64 10.63 14.95 22.17 34.40 9.21 196 - 200 1.64 8.47 16.39 34.81 30.19 6.04 200 - 204 0.90 6.33 9.94 24.33 49.40 8.19 204 -208 0.32 1.62 4.53 9.66 68.27 14.95 208 - 212 0.68 1.36 2.72 3.31 75.17 16.07 212 - 216 2.80 15.03 14.34 7.64 52.15 6.64 216 -220 3.92 14.76 16.57 10.43 46.82 7.51 220 -224 17.16 24.66 22.25 10.38 22.07 3.21 224 -228 26.35 25.56 20.48 9.01 14.73 2.61 228 - 232 24.20 24.58 19.69 14.34 14.09 2.07 232 - 236 13.89 19.97 19.05 27.39 16.58 2.46 236 -240 2.32 5.30 5.30 4.24 61.88 18.65 172 Westham 29 Percent in each size category Westham 30 Percent in each size category depth %>250 %250- %180- %125- %60- %<4 um depth %>250 %250- %180- %125- %60- %<4 (cm) nm 180um 125um 60um 4um (cm) (im 180um 125um 60um 4um um 0 - 4 2.00 1.33 1.33 1.78 66.97 24.92 4 - 8 1.67 1.67 2.33 3.00 70.25 17.75 8 - 12 1.33 3.33 4.67 3.77 64.35 19.55 12 - 16 2.00 2.67 1.33 2.36 66.46 21.85 16 - 20 2.33 0.67 2.00 4.49 70.13 17.05 20 - 24 2.00 1.33 1.00 3.91 72.08 17.02 24 - 28 1.67 1.00 1.33 2.66 73.52 15.49 28 - 32 2.67 1.00 1.00 2.64 39.71 51.98 32 - 36 2.00 1.33 1.00 1.50 45.40 47.09 36 - 40 2.00 1.33 2.00 3.07 73.10 16.83 40 - 44 2.33 1.00 1.67 4.11 73.55 15.68 44 -48 2.33 0.67 1.33 3.79 77.63 13.25 48 - 52 2.00 3.67 4.00 5.20 65.69 15.77 52 - 56 2.67 3.00 4.00 3.49 68.38 15.46 56 - 60 15.50 19.00 11.00 14.98 31.19 7.33 60 - 64 3.00 6.00 7.50 11.05 59.86 8.59 64 - 68 22.25 24.48 14.53 5.90 25.92 5.75 68 - 72 20.00 28.00 18.00 33.33 72 - 76 26.17 24.67 16.83 4.46 21.75 4.96 76 - 80 16.67 28.33 24.83 5.22 20.08 4.36 80 - 84 8.67 16.67 18.00 5.05 43.74 5.54 84 - 88 5.77 17.18 41.15 17.58 9.93 2.49 88 - 92 3.33 6.00 7.33 16.09 57.49 8.09 92 - 96 2.67 4.00 4.00 13.36 66.90 7.07 96 - 100 2.67 4.33 18.00 18.56 46.26 8.84 100 - 104 3.00 10.25 35.25 17.17 28.43 4.90 104 - 108 2.75 7.25 17.00 7.85 46.91 15.99 108 - 112 3.00 2.00 5.00 9.74 65.93 13.67 112 - 116 3.50 4.25 10.25 35.02 38.59 7.64 116 - 120 2.50 4.75 14.75 28.58 41.87 6.80 120 - 124 27.00 12.75 7.75 8.06 35.29 7.65 124 - 128 21.17 13.17 18.67 20.11 21.55 4.68 128 - 132 32.65 18.37 13.39 14.05 14.08 2.35 132 - 136 22.83 21.33 16.67 10.28 21.16 3.89 136 - 140 23.30 29.19 25.57 12.82 6.97 1.02 140 - 144 34.60 13.60 7.00 4.58 32.83 6.19 144 - 148 28.86 30.00 17.43 6.32 14.12 2.71 148 - 152 23.05 27.16 24.68 9.08 12.59 2.68 152 - 156 27.20 22.20 18.00 8.26 17.85 6.29 0 -4 3.5 2.34 1.16 2 81.32 12 4 - 8 *2.00 1.20 1.20 6.59 71.83 14.38 8 - 12 2.00 1.60 2.00 3.65 70.59 16.96 12 - 16 2.80 1.20 2.40 5.31 69.62 16.67 16 - 20 2.40 1.20 1.20 5.69 71.58 15.94 20 - 24 3.20 0.00 0.80 2.74 78.26 13.40 24 - 28 4.00 2.40 1.60 6.06 70.15 14.19 28 -32 2.40 1.20 0.80 5.17 72.81 14.41 32 -36 2.40 6.80 1.60 8.60 68.54 8.86 36 -40 3.20 2.80 1.60 7.23 71.45 10.53 40 -44 4.00 0.80 0.80 7.30 74.42 9.48 44 -48 2.40 2.40 1.20 6.87 71.26 13.47 48 - 52 2.40 4.40 7.60 9.32 60.65 13.23 52 - 56 2.80 6.40 11.20 13.13 51.61 12.06 56 - 60 7.40 24.40 21.40 14.23 23.43 6.54 60 - 64 11.00 22.25 12.00 16.54 30.61 5.36 64 -68 10.75 25.25 14.75 11.59 30.85 6.06 68 - 72 4.33 9.67 13.33 20.49 41.62 8.55 72 - 76 3.00 8.00 12.00 30.02 36.94 9.04 76 - 80 2.67 6.00 16.67 27.98 36.55 8.14 80 - 84 2.33 3.00 8.00 27.83 49.84 6.66 84 - 88 2.33 5.00 10.00 18.01 48.16 13.17 88 -92 3.33 1.67 5.33 32.41 44.37 9.88 92 -96 2.33 1.33 4.00 37.26 46.78 6.62 96 - 100 1.44 1.80 4.32 30.04 55.56 6.84 100 - 104 1.00 4.00 6.33 24.87 51.65 10.14 104 - 108 2.33 8.67 12.33 35.86 31.87 7.61 108 - 112 1.33 2.33 10.00 38.65 38.65 6.36 112 - 116 4.33 7.33 10.67 33.51 37.17 5.65 116 - 120 7.33 19.00 15.33 27.69 25.05 4.59 120 - 124 5.33 18.33 22.00 13.04 36.52 3.45 124 - 128 6.50 17.50 29.75 128 - 132 3.67 5.00 10.33 37.36 36.64 6.00 132 - 136 11.67 10.67 14.67 30.23 25.76 4.34 136 - 140 17.00 11.67 10.33 20.18 33.09 5.40 140 - 144 3.67 8.00 10.00 29.88 39.73 7.39 144 - 148 6.67 11.00 7.33 28.62 36.50 9.22 148 - 152 15.50 23.25 19.00 152 - 154 39.61 29.64 9.56 154 - 156 39.31 36.27 2.95 9.57 8.80 2.08 156 - 158 33.00 40.17 10.50 158 - 160 30.74 44.50 8.25 9.13 5.28 1.12 173 Appendix 5: Results of Heavy Metal Analysis Barber 27: Heavy Metal Results Sample(cm) A l % Ba(ppm) Cu(ppm) Fe(%) Hg (ppb) Mn (ppm) Ni (ppm) Pb (ppm) Zn (ppm) 0 -5 2.41 90 49 4.14 80 1145 53 12 92 6-10 2.43 90 48 4.14 70 885 49 12 92 11 - 15 2.47 90 47 4.24 80 1095 51 14 92 16-20 2.20 100 44 4.06 60 1025 51 10 96 21 - 25 2.08 100 41 3.77 60 890 45 12 86 26-35 1.97 100 40 3.71 80 580 43 12 86 36-45 1.67 100 37 3.23 60 345 41 10 76 46-55 1.66 110 36 3.19 60 330 40 10 76 56-65 1.43 130 37 3.17 110 330 39 14 74 66-75 1.45 130 35 2.70 60 295 50 8 76 76-90 1.31 110 31 2.75 140 300 43 8 68 91-105 1.24 110 28 2.69 60 310 41 6 64 106-120 1.25 100 29 2.46 40 265 55 6 70 121-135 1.29 100 30 2.59 50 265 43 6 68 136-150 1.46 110 34 3.08 60 325 42 10 72 151-170 1.44 110 31 3.02 50 350 39 8 68 171-190 1.28 120 33 3.22 60 400 41 8 70 Duck 20: Heavy Metal Results Sample(cm) A l % Ba (ppm) Cu (ppm) Fe (%) 0-4 2.21 70 49 3.82 5-8 2.22 80 62 3.63 9- 12 2.14 90 41 3.76 13 - 16 2.01 90 83 3.65 17-20 2.00 80 40 3.77 21-25 1.86 80 38 3.62 26-30 1.89 90 43 3.60 31-40 1.97 90 36 2.91 41-50 1.99 100 38 2.73 51-60 2.02 100 60 2.68 61-70 2.05 110 41 2.93 71-80 1.96 110 59 2.93 81 -90 1.69 100 37 3.47 91 - 100 1.43 110 61 2.96 101 - 110 1.81 210 52 4.10 111 - 130 1.60 180 53 3.50 131 - 150 1.63 110 64 3.63 Hg (ppb) Mn (ppm) Ni (ppm) Pb (ppm) Zn (ppm) 60 860 47 16 100 60 710 45 16 98 50 865 49 10 92 60 710 48 10 96 60 1050 47 14 86 60 715 40 404 84 50 475 38 10 92 50 285 45 8 90 60 285 44 8 88 60 285 48 10 94 70 305 51 8 90 60 290 45 8 98 170 295 42 8 84 40 280 45 6 82 100 375 70 10 106 50 385 v 57 8 84 50 415 47 6 82 174 Duck 31: Heavy Metal Results Sample(cm) A l % Ba (ppm) Cu (ppm) Fe (%) Hg (ppb) Mn (ppm) Ni (ppm) Pb (ppm) Zn (ppm) 0-4 2.08 70 41 3.24 60 345 42 12 96 5-8 1.98 70 38 2.92 60 320 42 14 88 9-12 2.27 80 43 3.01 70 340 50 16 100 13 - 16 2.11 80 44 2.99 70 325 54 14 98 17-20 2.16 90 44 3.05 80 330 53 12 94 21-25 1.90 90 40 2.86 60 310 47 12 90 26-30 1.84 90 39 2.80 60 305 44 8 88 31-40 1.72 90 37 2.72 80 305 43 12 82 41-50 1.63 90 34 2.72 60 295 41 8 76 51-60 1.71 90 34 2.77 50 300 42 10 78 61 -70 1.90 100 40 3.14 60 345 46 10 84 71 -80 1.74 120 52 3.22 60 335 77 16 96 81 -90 1.87 120 49 3.56 80 340 67. 18 100 91 - 100 1.98 110 41 3.40 70 360 49 ' 10 90 101 - 110 1.78 110 40 3.19 80 385 72 12 88 111 - 130 1.69 120 40 3.31 80 365 52 8 78 131 -150 1.53 110 37 3.44 60 385 49 8 74 Lulu 33: Heavy Metal Results Sample A l % Ba (ppm) Cu (ppm) Fe (%) Hg (ppb) Mn (ppm) Ni (ppm) Pb (ppm) Zn (ppm) (cm) 0-5 1.99 50 39 3.24 50 305 41 10 92 6-10 1.97 50 38 3.37 50 280 36 10 80 11 -15 2.05 60 40 3.50 70 285 39 12 84 16-20 2.05 50 42 3.34 60 305 46 14 94 21-25 2.05 50 40 3.40 60 320 48 12 92 26-35 2.06 60 41 3.69 70 335 48 10 90 36-49 2.11 60 42 3.87 80 355 50 10 92 50-63 2.01 60 38 3.73 70 355 50 8 88 64-77 2.06 60 40 3.65 60 360 46 10 92 78-91 1.82 50 36 3.35 70 320 43 8 78 92 - 105 1.71 50 35 3.46 60 345 43 TO 76 106-119 1.76 60 31 3.56 80 365 44 6 78 120-133 1.78 60 34 4.28 50 415 52 10 82 134-147 1.56 50 35 4.86 60 425 60 14 86 148-161 1.51 50 103 4.34 70 375 48 8 88 162-175 1.57 50 63 4.69 80 385 45 16 90 176-190 1.77 50 33 3.71 320 380 42 6 76 191-205 1.88 60 34 3.80 80 425 47 8 78 1 7 5 Wood 21: Heavy Metal Results Sample(cm) A l % Ba(ppm) Cu(ppm) Fe(%) Hg (ppb) Mn (ppm) Ni (ppm) Pb (ppm) Zn( 0-5 1.85 90 48 3.30 50 365 51 10 92 6- 10 1.86 80 88 3.18 50 330 43 10 94 11-20 1.77 80 38 2.93 60 335 47 12 86 21-30 1.73 80 41 3.08 60 340 47 12 86 31 -40 1.76 90 40 3.16 60 385 50 8 84 41-50 1.85 90 40 3.31 70 390 49 10 88 51-65 1.75 90 36 3.13 60 380 47 10 80 66-80 1.68 100 39 3.11 220 395 51 10 80 81-95 1.60 90 32 3.05 60 400 42 8 74 96-110 1.55 90 35 2.98 50 380 39 8 72 111-125 1.47 80 32 2.94 80 385 39 8 70 126- 145 1.35 90 31 2.79 60 390 37 8 66 146-165 1.61 110 34 3.20 60 480 44 8 78 166-185 1.49 100 32 2.96 80 460 40 8 72 186 -205 1.54 110 32 3.04 50 475 42 10 74 206 - 225 1.77 110 35 3.34 50 515 43 8 76 226 - 230 1.33 100 36 2.98 40 460 40 8 64 West 29: Heavy Metal Results Sample A l % Ba (ppm) Cu (ppm) Fe (%) Hg (ppb) Mn (ppm) Ni (ppm) Pb (ppm) Zn (cm) 0-5 1.60 90 102 3.59 100 410 59 20 100 6-10 1.56 90 75 3.54 80 410 51 20 84 11 - 15 1.74 90 42 3.65 90 420 49 8 78 16-20 1.72 90 38 3.83 90 420 47 8 76 21-25 1.54 80 41 3.63 90 395 46 6 74 26-30 1.48 80 40 3.71 90 375 46 8 74 31-38 1.40 70 29 3.27 50 335 38 8 68 39-46 1.32 70 31 3.21 60 340 38 6 68 47- 54 1.54 80 37 3.47 70 360 42 8 78 55-62 1.42 70 32 3.08 60 330 41 8 68 63-70 1.26 60 29 2.89 60 305 40 6 62 71 -78 1.48 80 33 3.14 60 325 45 8 74 79-86 1.63 80 34 3.31 70 325 48 8 78 87-95 1.56 70 79 3.34 60 310 43 8 80 96-105 1.70 70 37 3.22 190 295 45 8 82 106-125 1.70 70 36 3.08 100 300 43 10 78 126-145 1.70 60 35 3.07 50 295 39 8 78 (ppm) 176 West 30: Heavy Metal Results Sample A l % Ba (ppm) Cu (ppm) Fe (%) (cm) 0-3 2.02 60 42 3.26 4-6 2.10 60 42 3.27 7-9 1.78 60 135 3.06 10- 12 1.81 60 40 3.29 13 - 15 1.69 60 280 3.10 16-20 1.60 60 36 3.04 21 -25 1.74 70 55 3.18 26-30 1.64 70 33 3.06 31-40 1.53 70 83 3.09 41-50 1.65 70 33 3.30 51-60 1.48 70 76 3.34 61-70 1.49 70 32 3.37 71-80 1.42 70 37 3.44 81-90 1.44 70 52 3.52 91 - 100 1.24 70 30 3.16 101 - 120 1.22 80 28 3.37 121 - 140 1.55 90 46 3.74 Hg (ppb) Mn (ppm) Ni (ppm) Pb (ppm) Zn (ppm) 60 350 43 10 90 100 335 45 12 94 70 310 39 10 96 60 310 44 10 84 50 295 37 10 114 50 285 38 10 74 80 330 46 8 86 60 300 44 10 78 60 285 41 6 78 60 340 44 6 76 80 320 39 8 76 70 345 41 6 74 50 355 40 10 74 60 370 44 8 74 60 370 42 8 64 60 420 41 6 62 70 500 44 8 74 177 Appendix 6: 1 3 7 Cs Analysis Results Barber 27 Duck 20 Lulu 33 1st attempt depth (cm) Bq/kg +/- Westham 29 depth (cm) Bq/kg +/-5-7 19.6 10 30-32 24.6 4.4 14-16 4.5 < 40-42 10.9 3.3 34-36 3.6 < 50-52 5.5 < depth (cm) Bq/kg +/- Westham 30 depth (cm) Bq/kg +/-10-12 26 4.2 20-22 15.6 4.3 20-22 3.8 < 30-32 21.6 5.4 40-42 20.6 5 depth (cm) Bq/kg +/- 50-52 5.7 < 0-2 10 < 2-4 9 < Woodward 21 depth (cm) Bq/kg +/-4-6 11 < 34-36 37.1 4.8 6-8 7 < 44-46 28.8 5.8 8-10 8 < 64-66 5.5 < 10-12 10 < 74-76 5.6 < 12-14 11 < 14-16 11 < Lulu 33 depth cm Bq/kg +/-16-18 9 < 2nd attempt 0-2 11 3 18-20 10 < 44-46 25 4.5 20-22 11 < 46-48 13.3 1.8 22-24 10 < 48-50 10.4 2.2 24-26 10 < 54-56 3.7 < 26-28 10 < 60-62 4.7 < 28-30 12 < 64-66 4.2 < 30-32 23 11 68-70 3.1 < 32-34 32 10 74-76 2.4 < 34-36 37 12 78-80 3.7 < 36-38 25 10 38-40 28 9 Note: Duck 31 and Westham 15 dated at GSC lab (all 48-50 10 < others at University of Toronto). 37 Bq/kg = 1 pCi/g 78-80 11 < * values corrected for background Duck 31 depth cm pCi/g +/- % Bq/kg depth cm pCi/g +/- % Bq/kg * 0-2 0.12 33.3 4.42668 1.5-3.5 0.16 11.66 5.93517 2-4 0.19 16.3 7.1965 4-5 0.148 16.14 5.46046 4-6 0.17 24.8 6.22932 5-6.5 0.119 20.03 4.40892 6-8 0.28 10.9 10.54463 6.5-8.5 0.148 13.75 5.49413 8-10 0.89 3.92 32.97181 8.5-10.5 0.178 11.8 6.5786 10-12 0.55 5.24 20.35962 10.5-12.5 0.2 10.49 7.39889 12-14 0.28 11.4 10.35963 12.5-14.5 0.304 7.82 11.23542 14-16 0.05 39.6 2.02094 14.5-16.5 0.225 9.25 8.34091 16-18 -0 298 -0.12025 16.5-18.5 0.186 16.27 6.87275 18-20 0.02 86 0.71003 18.5-20.5 0.113 8.83 4.18248 20-22 -0.02 -180 -0.91427 20.5-22.5 0.059 13.49 2.16524 22-24 0.02 71 0.67044 22.5-24.5 0.013 24.93 0.4699 32-34 -0.01 2284 -0.28638 24.5-26.5 0.016 34.32 0.57609 40-42 0.01 81.1 0.19758 26.5-28.5 0.016 70.23 0.57498 48-50 0 142 0.00037 36.5-38.5 -0.01 -1159 -0.35742 58-60 0.01 68.1 0.38702 178 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0089776/manifest

Comment

Related Items