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Recent Deglacierization of the Upper Wheaton River Watershed, Yukon

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Recent Deglacierization of the Upper Wheaton River Watershed, Yukon RECENT DEGLACIERIZATION OF THE UPPER WHEATON RIVER WATERSHED, YUKON by Amber Church Double Honours B.Sc. with Distinction University of Victoria 2004 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE In the Department of Earth Sciences © Amber Kimberley Smokey Church 2011 SIMON FRASER UNIVERSITY SPRING 2011 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: Amber Church Degree: Master of Science Title of Thesis: Recent Deglacierization of the Upper Wheaton River Watershed, Yukon Examining Committee: Chair: Dr. Andy Calvert Professor, Department of Earth Sciences Dr. John Clague Senior Supervisor Professor, Department of Earth Sciences Dr. Brent Ward Supervisor Associate Professor, Department of Earth Sciences Dr. Jeff Bond Supervisor Surficial Geologist, Yukon Geological Survey Dr. Andr~e Blais-Stevens External Examiner Geological Survey ofCanada Date Defended/Approved: November 8, 20 I0 ii Declaration of Partial Copyright Licence The author, whose copyright is declared on the title page of this work, has granted to Simon Fraser University the right to lend this thesis, project or extended essay 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 library of any other university, or other educational institution, on its own behalf or for one of its users. The author has further granted permission to Simon Fraser University to keep or make a digital copy for use in its circulating collection (currently available to the public at the “Institutional Repository” link of the SFU Library website <www.lib.sfu.ca> at: <http://ir.lib.sfu.ca/handle/1892/112>) and, without changing the content, to translate the thesis/project or extended essays, if technically possible, to any medium or format for the purpose of preservation of the digital work. The author has further agreed that permission for multiple copying of this work for scholarly purposes may be granted by either the author or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shall not be allowed without the author’s written permission. Permission for public performance, or limited permission for private scholarly use, of any multimedia materials forming part of this work, may have been granted by the author. This information may be found on the separately catalogued multimedia material and in the signed Partial Copyright Licence. While licensing SFU to permit the above uses, the author retains copyright in the thesis, project or extended essays, including the right to change the work for subsequent purposes, including editing and publishing the work in whole or in part, and licensing other parties, as the author may desire. The original Partial Copyright Licence attesting to these terms, and signed by this author, may be found in the original bound copy of this work, retained in the Simon Fraser University Archive. Simon Fraser University Library Burnaby, BC, Canada Last revision: Spring 09 ABSTRACT My research involves the study of Wheaton Glacier, the largest glacier in the Wheaton River watershed in southern Yukon Territory. Since the Little Ice Age, Wheaton Glacier has lost 50% of its area and 58% to 63% of its volume. Despite increasing winter snowfall, rising temperatures continue to drive the persistent negative mass balance of the glacier. Periglacial activity, precipitation events, and glacier recession are affecting sediment delivery in the upper Wheaton River watershed. Sediment is moving downstream from the Wheaton Glacier forefield and large, out-of-channel debris flows are impacting the fan at the mouth of the valley. Evidence from sediment cores collected on the distal part of the fan suggests that debris flows have dominated sedimentation at the mouth of the valley during the last half of the Holocene, coincident with Neoglacial advances and the historic period of rapid glacier retreat. Keywords: Holocene deglacierization; climate change; debris flows; Wheaton River; Yukon Subject Terms: Quaternary geology; geomorphology iii DEDICATION This work is dedicated to my loving and ever-patient friends and family who have always encouraged and supported me. In particular, my husband, Tyler Kuhn, saw me through every step of the thesis process; from keeping me sane as I waded through an increasingly overloaded schedule, to pounding cores into unyielding debris flow deposits, to gently prodding me to finish. iv ACKNOWLEDGEMENTS I wish to thank Dr. John Clague for his guidance and support throughout this project and my supervisory committee members – Jeff Bond and Dr. Brent Ward – for all of their help. I thank the Yukon Geological Survey, the National Science and Engineering Research Council of Canada, the Yukon Mining and Petroleum Environmental Research Group, the Association for Canadian Universities for Northern Studies, the Northern Scientific Training Program, and the Northern Research Institute for their financial, logistical, and moral support. Tyler Kuhn, Kayla Vickers, and Denny Capps provided excellent assistance in the field under often challenging conditions. v TABLE OF CONTENTS Approval .............................................................................................................. ii Abstract .............................................................................................................. iii Dedication .......................................................................................................... iv Acknowledgements ............................................................................................ v Table of Contents ............................................................................................... vi List of Figures .................................................................................................. viii List of Tables .................................................................................................... xiii 1: Introduction ..................................................................................................... 1 1.1 Project Overview................................................................................. 1 1.2 Objectives ........................................................................................... 2 1.3 Wheaton River .................................................................................... 2 1.3.1 Physiography .................................................................................. 2 1.3.2 Climate ............................................................................................ 3 1.3.3 Bedrock Geology ............................................................................. 3 1.3.4 Glacial Geology ............................................................................... 5 1.4 Holocene Climate ............................................................................... 5 1.4.1 Neoglaciation .................................................................................. 7 1.4.2 Historic Climate Change .................................................................. 8 1.4.3 ENSO and PDO ............................................................................ 10 1.5 Thesis Structure................................................................................ 12 2: WHEATON GLACIER .................................................................................... 13 2.1 Introduction ....................................................................................... 13 2.2 Objectives ......................................................................................... 13 2.2.1 Study Site ...................................................................................... 14 2.3 Methods ............................................................................................ 14 2.3.1 Glacier Area Loss and Downwasting............................................. 14 2.3.2 Bivariate Scaling Analysis and Volume Estimates ........................ 16 2.3.3 Geomorphology ............................................................................. 17 2.3.4 Lichenometry ................................................................................. 17 2.3.5 Climate Analysis ............................................................................ 19 2.4 Results .............................................................................................. 22 2.4.1 Glacier Ice Loss ............................................................................ 22 2.4.2 Geomorphology and Chronology .................................................. 22 2.4.3 Climate .......................................................................................... 31 2.5 Discussion ........................................................................................ 34 2.5.1 Lichenometry and Glacier Retreat ................................................. 34 vi 2.5.2 Link between Climate and Activity of Wheaton Glacier ................. 42 2.6 Conclusion ........................................................................................ 44 3:
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