THE QUATERNARY HISTORY OF THE CORDILLERAN ICE SHEET FRINGE, ASHLEY LAKE AREA, MONTANA by Denny Lane Capps A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Earth Science MONTANA STATE UNIVERSITY Bozeman, Montana January 2004 ©Copyright by Denny Lane Capps 2004 All Rights Reserved ii APPROVAL of a thesis submitted by Denny Lane Capps This thesis has been read by each member of the thesis committee and has been found to be satisfactory regarding content, English usage, format, citations, bibliographic style, and consistency, and is ready for submission to the College of Graduate Studies. Dr. William Locke Approved for the Department of Earth Sciences Dr. David Lageson Approved for the College of Graduate Studies Dr. Bruce McLeod iii STATEMENT OF PERMISSION TO USE In presenting this thesis in partial fulfillment of the requirements for a master’s degree at Montana State University, I agree that the Library shall make it available to borrowers under rules of the Library. If I have indicated my intention to copyright this thesis by including a copyright notice page, copying is allowable only for scholarly purposes, consistent with “fair use” as prescribed in the U.S. Copyright Law. Requests for permission for extended quotation from or reproduction of this thesis in whole or parts may be granted only by the copyright holder. Denny Lane Capps January 12th, 2004 iv ACKNOWLEDGEMENTS 1. Dr. William Locke, advisor, who was always there, introduced me to the problem and oversaw the project work 2. Dr. Kenneth Pierce, committee member, who shared his extensive field knowledge and encouragement throughout the project 3. Dr. John Montagne, committee member, who selflessly gave his time to the betterment of this thesis 4. This study was primarily funded by a generous donation of the Donald Smith Memorial Scholarship Fund 5. Jeff Deems – friend and colleague, continuous encouragement and positive criticism 6. Dr. Larry Smith – Montana Bureau of Mines and Geology – regional geologic information and encouragement 7. Gamma Family – land access, hospitality and local information 8. Scott Larson – field assistance 9. Plum Creek Timber Company – land access and aerial photos 10. Stoltz Timber Company – land access and maps 11. Flathead National Forest – especially Jane Kollmeyer, District Ranger – painless permitting and campground use 12. Dr. Sharon Eversman – MSU Department of Ecology – plant identification 13. Brist Family – land access 14. Montana DNRC - lake bathymetry v TABLE OF CONTENTS 1. INTRODUCTION..............................................................................................................................1 Problem.........................................................................................................................1 Objective.......................................................................................................................8 Study Area .................................................................................................................... 8 Regional Setting.................................................................................................... 10 Topography..................................................................................................... 10 Geology........................................................................................................... 11 Climate............................................................................................................ 15 Ice ................................................................................................................... 16 Vegetation....................................................................................................... 19 Local Setting ......................................................................................................... 19 Topography..................................................................................................... 19 Geology........................................................................................................... 20 Climate............................................................................................................ 23 Ice ................................................................................................................... 24 Vegetation....................................................................................................... 24 2. METHODS .......................................................................................................................................26 Erratics ........................................................................................................................ 26 Depositional Landforms.............................................................................................. 28 Moraines ............................................................................................................... 29 Kames ................................................................................................................... 29 Glacial Depressions .............................................................................................. 29 Erosional Landforms................................................................................................... 30 Lateral Meltwater Channels.................................................................................. 30 Direct Overflow Channels .................................................................................... 31 Weathering Rinds........................................................................................................ 32 Bog Augering.............................................................................................................. 36 Tephras.................................................................................................................. 37 Radiocarbon .......................................................................................................... 39 Ice Modeling ............................................................................................................... 40 vi TABLE OF CONTENTS - CONTINUED 3. RESULTS..........................................................................................................................................43 Erratics ........................................................................................................................ 43 Depositional Landforms.............................................................................................. 45 Moraines ............................................................................................................... 45 Kames ................................................................................................................... 47 Glacial Depressions .............................................................................................. 47 Erosional Landforms................................................................................................... 49 Lateral Meltwater Channels.................................................................................. 49 Direct Overflow Channels .................................................................................... 49 Weathering Rinds........................................................................................................ 50 Bog Augering.............................................................................................................. 52 Tephras.................................................................................................................. 52 Radiocarbon .......................................................................................................... 55 Varves ................................................................................................................... 57 Ice Modeling ............................................................................................................... 58 4. DISCUSSION ..................................................................................................................................62 Discussion of Features ................................................................................................ 62 Erratics .................................................................................................................. 62 Depositional Landforms........................................................................................ 63 Erosional Landforms............................................................................................. 65 Weathering Rinds.................................................................................................. 65 Bog Augering........................................................................................................ 66 Defining Significant Ice Margins that Created Figures .............................................. 67 Erratics .................................................................................................................. 67 Depositional Landforms........................................................................................ 70 Erosional Landforms............................................................................................. 73 Bog Augering.......................................................................................................