The Late Quarternary Geomorphic History of the Sumas Valley
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THE LATE QUATERNARY GEOMORPHIC HISTORY OF THE SUMAS VALLEY by Valerie J. Cameron B.A.(Hons.), Simon Fraser University, 1976 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS in the Department of Geography O Valerie J. Cameron 1989 SIMON FRASER UNIVERSITY July, 1989 All rights reserved. This work may not be reproduced in whole or in part , by photocopy or other means, without permission of the author. APPROVAL Name : Valerie Jean Cameron Degree: Master of Arts Title of Thesis: The Late Quaternary Geamorphic History of the Sumas Valley Examining Committee: Chair: A.M. Gill, Assistant Professor M.C. Roberts Professor Senior Supervisor ' ' _.__IE.J.--- HiEkin- Professor - - - A.C.R. Roberts Associate Professor Institute for Quaternary Research - SFU Research Scientist Geological Survey of Canada Date Approved: July 28, 1989 PARTIAL COPYRIGHT LICENSE I hereby grant to Simon Fraser University the right to lend my thesis, proJect or extended essay (the title of which is shown below) to users of the Simon Fraser University Library, and to make partial or single copies only for such users or In response to a request from the l ibrary of any other university, or other educational Institution, on its own behalf or for one of its users. I further agree that permission for multiple copying of this work for scholarly purposes may be granted by me or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shall not be allowed without my written permission, T i t l e of Thes i s/Project/Extended Essay The Late Quaternary Geomorphic History of the Sumas Valley Author: - I (signature) Valerie Jean Cameron ABSTRACT The Sumas Valley is located in the eastern portion of the,Fraser Lowland- of L- British Columbia. A long, flat-floored valley sandwiched between two elongate mountains and bordered at each end by rivers, the Sumas Valley's evolution has commanded much interest but only limited directed study. The objectives of this study were: 1) to reconstruct the geomorphic evolution of the Sumas Valley in Late Quaternary time by examination of the subsurface sedimentary architecture of the region, and 2) to address the question of whether the Fraser River (or a distributary) could have flowed through the valley and discharged into Bellingham Bay. To achieve these objectives, subsurface sample collection was necessary. Core obtained in the field was examined for texture, sedimentary structure, lithology, and organic matter content. Personally collected data was supplemented with water well drill logs and B.C. Department of Highways test hole data. Correlation of the data permitted the identification of nine lithostratigraphic units, which were then used to construct the subsurface sedimentary architecture of the Sumas Valley. The subsurface sedimentary architecture of Sumas Valley suggests that the most significant aspect of the Sumas Valley's evolution in post , glacial time was the progradation of two fans into a basin left by the downwasting of ' glacial ice. The fans are identified, in both the north end and the south end of the Sumas Valley, by lobes of gravel which display the lateral and vertical grading , patterns characteristic of a prograding fan or delta. The presence of Mazama tephra/ \ tin some of the cores, as well as the age of radiocarbon dated wood, places the deposition of these fan sediments clearly within the Holocene. , Lithological identification of sediments suggests that the source of the northern ' fan is the Chilliwack River, whereas the southern fan is believed to have originated iv from the progradation of the Nooksack River, or a greatly enlarged Sumas River, into the valley. The hypothesis of the Fraser River flowing through the Sumas Valley during the Holocene is rejected due to the obstacle presented by the Nooksack gravel lobe in the southern portion of the valley and because of the absence of Fraser River- sediments in the valley. DEDICATION This thesis is dedicated to Victor and Crystal. ACKNOWLEDGEMENTS I would like to express my thanks to the many colleagues, friends, and family who made the completion of this thesis possible. Dr. M. C. Roberts deserves special recognition for providing guidance, inspiration, and funding. His helpful comments in writing this thesis were greatly appreciated. i would also like to express my appreciation to the members of my examining committee--Dr. L. Jackson, Dr. E. Hickin, and Dr. A. Roberts--for their many thoughtful suggestions. Special thanks go out to the many members of my field crew, who endured sometimes uncomfortable conditions for the sake of science: Bill Ophoff, Nancy Hori, Harry Jol, Harry Williams, Greg Brooks, Butch Morningstar, and Jody Udell. Sandy Vanderburgh, Kate Cooksley, and Vera Law offered many helpful suggestions in the last stages of this project. I would like to express my gratitude to Alan, without whose cooperation this project would not have been made possible. vi i TABLE OF CONTENTS APPROVAL................................................................................................................................... ii ... ABSTRACT ..................................................................................................................................111 DEDICATION................................................................................................................................ v ACKNOWLEDGMENTS ............................................................................................................vi LIST OF TABLES......................................................................................................................... x LIST OF FIGURES...................................................................................................................... xi CHAPTER ONE: INTRODUCTION 1.0 Introduction............................................................................................................... 1 1. 1 Objectives.................................................................................................................. 1 1.2 Study Area ................................................................................................................4 1.2.0 Bedrock Geology ......................................................................................4 1.2.1 Surficial Geomorphology..................................................................... 10 i2.2 Evidence of Glaciation......................................................................... 13 1.3 Sumas Valley.. Previous Research................................................................... 14 CHAPTER TWO: METHODOLOGY 2.0 Surficial Geomorphology..................................................................................... 22 2.1 Subsurface Methods............................................................................................. 24 2.2 Laboratory Analysis.............................................................................................. 27 CHAPTER THREE: LITHOSTRATIGRAPHY OF THE SUMAS VALLEY FILL 3.0 Lithostratigraphy of the Sumas Valley Fill........................................................ 29 3.0.1 Unit 1..Blue Clayey Silt .........................................................................47 3.0.2 Unit 2.. lnterbedded Sand and Silt ......................................................47 3.0.3 Unit 3..Gravel.. Southern Valley ..........................................................49 3.0.4 Unit 4..Gravel- Nort hern Valley ........................................................... 51 viii 3.0.5 Unit 5..Sand.. Southern Cores............................................................ 52 3.0.6 Unit 6..Sand.. Nort hern Cores............................................................. 52 3.0.7 Unit -/..Silt.. Fluvial Proximal................................................................ 53 3.0.8 Unit 8.. Clayey Si It ..................................................................................53 3.0.9 Unit 9.. Silt and Fine Sand.................................................................... 53 CHAPTER FOUR: SEDIMENTARY ARCHITECTURE OF THE SUMAS VALLEY 4.0 Introduction............................................................................................................. 55 4.1 Longitudinal Sections........................................................................................... 55 4.1.0 Central Valley--Transect A ....................................................................55 4.1 .1 Valley Flank.. Transect I......................................................................... 58 4.1.2 Longitudinal Sections.. Summary .......................................................60 4.2 Cross Valley Sections.......................................................................................... 61 4.2.0 Northern Valley-Transects B & K........................................................ 62 4.2.1 Cent rat Valley.. Transects C, D. & E.................................................... 63 4.2.2 Western Valley.. Transects F & N......................................................... 65 4.2.3 Southern Valley.. Transects L & M..................................................... -66 4.2.4 Cross Valley Sections..Summary .......................................................67 4.3 Discussion.............................................................................................................. 69 4.3.0 Unit 1........................................................................................................