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Late Pleistocene Evolution of Glacial Lake Purcell: a Potential Floodwater Source to the Channeled Scabland

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Late Pleistocene Evolution of Glacial Lake Purcell: a Potential Floodwater Source to the Channeled Scabland LATE PLEISTOCENE EVOLUTION OF GLACIAL LAKE PURCELL: A POTENTIAL FLOODWATER SOURCE TO THE CHANNELED SCABLAND by Jared L. Peters B.S., Bloomsburg University of Pennsylvania, 2009 A.A.S., Garrett College, 2005 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE In the Department of Geography Faculty of Environment © Jared L. Peters 2012 SIMON FRASER UNIVERSITY Fall 2012 All rights reserved. However, in accordance with the Copyright Act of Canada, this work may be reproduced, without authorization, under the conditions for “Fair Dealing”. Therefore, limited reproduction of this work for the purposes of private study, research, criticism, review and news reporting is likely to be in accordance with the law, particularly if cited appropriately. APPROVAL Name: Jared Peters Degree: Master of Science Title of Thesis: Late Pleistocene evolution of glacial Lake Purcell: a potential floodwater source to the Channeled Scabland Examining Committee: Chair: Dr. Eugene McCann Professor, Department of Geography ______________________________________ Dr. Tracy A. Brennand Senior Supervisor Associate Professor, Department of Geography ______________________________________ Dr. Olav Lian Supervisor Faculty, Department of Geography, University of the Fraser Valley Adjunct Professor, Department of Geography ______________________________________ Dr. Richard Waitt Internal Examiner Research Geologist, Cascade Volcano Observatory ______________________________________ Dr. Dan Smith External Examiner Professor Department of Geography, University of Victoria Date Defended/Approved: September 18, 2012 ii Partial Copyright Licence ABSTRACT The Quaternary history of the Channeled Scabland (CS) and its primary floodwater sources during marine isotope stage (MIS) 2 are well documented and understood. However, putative floodwaters from glacial lakes in British Columbia are poorly understood; these lakes may have supplied floodwaters to the CS in late MIS 2 during northward retreat of the Cordilleran Ice Sheet. This study combines geomorphology, sedimentology, stratigraphy, aerial photograph interpretation, ground penetrating radar, and geographic information science to reconstruct the paleogeography and evolution of glacial Lake Purcell in the Purcell Trench. Glacial Lake Purcell was a proglacial, ice-contact lake that was ~90 km long, up to 12 km wide, and ~360 m deep against its dam (Purcell Lobe). It contained >70 km3 of water just prior to drainage. It likely drained catastrophically (~47 km3 of water) down the Kootenay River valley into the Columbia River, though geomorphic evidence is equivocal. Keywords: Glacial Lake Purcell; ice-contact proglacial lake; jökulhlaup; Channeled Scabland; Cordilleran Ice Sheet; Purcell Trench iii DEDICATION For my Hazel Mae (a.k.a. the “Hazelhoff”, the “Hazinator”, “Hazalea”, “Donkey”, “Donkey Chowder”, “Chongles”, “Potatoes”, and “Sweet Petite”). iv ACKNOWLEDGEMENTS The people who live in the Kootenays are among the happiest and friendliest that I have met. They were extremely helpful, curious and tolerant of my explorations on their property. Among those who deserve thanks are Roland Proctor and his neighbours in Johnsons Landing, Bill and Leila McCaw in Balfour, Lenard and his family in Tarrys, and Dan in Castlegar. I am especially thankful to Rob and Sarah, who went above and beyond to make my assistant and I feel down right at home for a week—you guys are great and I will always consider you my friends. I thank you all and wish you the best. My field assistants, Andrew Perkins and Aaron Dixon were hard working, smart and positive throughout the two demanding field seasons. I couldn’t have done this without you guys—and I certainly wouldn’t have had as much fun. We spent two months in tents while we ate green hotdogs, cooked in tin cans, weathered storms, got interrogated by the US border patrol, threw axes, slaughtered chickens, drove thousands of kilometres, dug in hundreds of exposures, and counted thousands of clasts. My lab assistant, Lili Perreault saved me hours of tedious data entry that may have cost me my last marbles. Matthew Burke was an integral part of the GPR work in this thesis and served as an impromptu advisor. During his time at SFU he became a good friend and an “uncle Map”. Thanks to all my paleo-pals. v My committee members, Olav Lian and Richard Waitt, and my external supervisor, Dan Smith all provided knowledgeable and valuable advice. They all managed to read through my thesis on a very tight timeline and still provide poignant edits. Richard’s role was particularly important, for his original questions on Columbia River valley megaflood forms inspired this study—and he proved extremely helpful during the editing process. Tracy Brennand was an excellent advisor throughout this study. She is knowledgeable, hardworking and selflessly devoted to her students. In both the field and lab she was a leader, and during the occasional downtime she was a lot of fun. Tracy, I consider you a friend and myself lucky. I couldn’t have done this without you, thanks. This study was conducted while my wife, Britta and I started a family by bringing our daughter Hazel into the world. This was crazy. I couldn’t have gotten through this project without help from our friends on the “mountain” and in Vancouver, who provided us with much-needed social breaks and babysitting. Thanks to all of our friends. We will miss you. Most of all, I need to thank Britta and Hazel. Thanks for taking care of each other while I was away in the field or in the lab, and for putting up with me while I was at home. vi TABLE OF CONTENTS Approval .......................................................................................................................... ii Abstract .......................................................................................................................... iii Dedication ...................................................................................................................... iv Acknowledgements ......................................................................................................... v Table of Contents .......................................................................................................... vii List of Figures.................................................................................................................. x List of Tables ................................................................................................................ xxii 1: Introduction and research rationale ........................................................................ 1 1.1 Introduction ............................................................................................................. 1 1.2 Rationale ................................................................................................................. 2 1.2.1 A proposed flood from glacial Lake Kootenay .............................................. 4 1.2.2 Gradual drainage of glacial lakes in the Purcell Trench ............................... 6 1.3 Research questions ................................................................................................ 8 1.3.1 Primary research question ........................................................................... 8 1.3.2 Detailed research questions ........................................................................ 8 2: Literature review ....................................................................................................... 9 2.1 Ice-dammed lakes ................................................................................................... 9 2.1.1 Lake types ................................................................................................... 9 2.1.2 Dam failures .............................................................................................. 12 2.2 Megafloods and deglaciation ................................................................................. 14 2.2.1 The Channeled Scabland .......................................................................... 15 2.3 Deglacial history of southern BC valleys ............................................................... 21 2.3.1 Deglacial history of the Arrow Lakes basin ................................................ 23 2.3.2 Deglacial history of the southern Rocky Mountain Trench ......................... 23 2.3.3 Glacial Lakes in the Purcell Trench and northwestern Montana ................. 24 3: Study area................................................................................................................ 32 3.1 Geography ............................................................................................................ 32 3.1.1 Lake naming conventions used in this thesis ............................................. 38 3.2 Geology ................................................................................................................ 41 4: Methodology ............................................................................................................ 44 4.1 Field preparation ................................................................................................... 44 4.2 Field data collection and analysis .......................................................................... 45 4.2.1 Landform definitions .................................................................................. 55 4.2.2 GPR processing and analysis
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