Central Washington University Science Honors Research Program ROCK GLACIERS IN THE EASTERN CASCADES, WASHINGTON A Thesis submitted to the Science Honors Research Program Faculty of Central Washington University by Mark Weidenaar 2013 Mark Weidenaar Submitted in Partial Fulfillment of the Requirements for the Science Honors Research Program June 2013 The thesis of Mark Weidenaar was reviewed and approved by the following: FACULTY MENTOR ____________________________________________________________ Dr. Karl Lillquist, Geography HONORS THESIS COMMITTEE MEMBER ____________________________________________________________ Dr. Lisa Ely, Geology SCIENCE HONORS RESEARCH PROGRAM DIRECTOR ____________________________________________________________ Dr. Audrey D. Huerta, Director, Science Honors Research Program DATE____________________________ ABSTRACT ROCK GLACIERS IN THE EASTERN CASCADES, WASHINGTON Mark Weidenaar Faculty Mentor: Karl Lillquist, Ph.D. Geography The eastern portion of Washington State's Cascade Range is a place not previously examined for rock glaciers, due to proximity to the Pacific Ocean and its associated marine- influenced climate. The objectives of this study were to determine spatial, activity, and genesis patterns, and paleoclimatic implications of Eastern Cascade rock glaciers. Using Google Earth, I found 103 rock glaciers in the study area. Rock glaciers are more common further east of the Cascade crest and more north in latitude, with the largest concentrations occurring east of Lake Chelan (22) and in the Pasayten Wilderness (28) in the North Cascades. None were found south of the Goat Rocks. Rock glaciers generally face north to northeast. Genesis types include 72 debris, 23 gelifluction, and 8 glaciogenic types. Debris- type rock glaciers occur throughout the range and from 20-70km east of the crest. Gelifluction-types also generally occur north of 48°N, and range from 25-45km east of the crest. Glaciogenic-types occur north of 48°N and <40km east of the crest. Activity levels rise with elevation, with 31 active rock glaciers above 2000m, 55 inactive between 1600-2200m, and 18 relict below 1900m. These patterns suggest a strong past and present climatic role in determining Eastern Cascade rock glacier distribution. Out of the eight rock glaciers visited in the field, five are Little Ice Age features, while two are much older. These eight rock glaciers and data from other sources suggest a 250-300m rise in the 0°C isotherm over the last 100-150 years, with a 2°C general increase in temperature in the Eastern Cascades since the end of the Little Ice Age. iii TABLE OF CONTENTS TITLE PAGE i SIGNATURE PAGE ii ABSTRACT iii TABLE OF CONTENTS iv SECTION 1 Introduction 1 1.1 Research Problem 1 1.2 Research Purpose 2 1.3 Research Significance 3 SECTION 2 Literature Review 4 2.1 Rock Glacier Spatial Distribution 4 2.1.1 Geologic Controls 4 2.1.2 Climatic Controls 5 2.2 Rock Glacier Genesis 8 2.2.1 Glacial Origins 8 2.2.2 Periglacial Origins 9 2.2.3 Modern Genesis Classification Schemes 10 2.3 Rock Glacier Activity 11 2.3.1 Active Rock Glaciers 12 2.3.2 Inactive Rock Glaciers 13 2.3.3 Relict Rock Glaciers 13 2.4 Rock Glacier Age 13 2.4.2 Late Pleistocene 14 2.4.3 Holocene 15 SECTION 3 Study Area 17 3.1 General Description 17 3.2 Eastern Cascade Geology 18 3.3 Climate 19 3.4 Cascade Geomorphology 20 3.4.1 Glacial History 20 iv 3.4.2 Mass Wasting, Fluvial and Weathering Processes 21 3.5 Eastern Cascade Flora 21 SECTION 4 Methods 22 4.1 Rock Glacier Spatial Distribution 22 4.2 Rock Glacier Genesis Classification 24 4.3 Rock Glacier Activity Levels 25 4.4 Rock Glacier Ages 26 4.5 Paleoclimatic Data 28 SECTION 5 Results/Discussion 30 5.1 Spatial Distribution 30 5.1.1 Latitude 37 5.1.2 Elevation 38 5.1.3 Aspect 41 5.1.4 Distance from crest 42 5.2 Genesis 45 5.2.1 Glaciogenic Rock glaciers 45 5.2.2 Gelifluction Rock glaciers 47 5.2.3 Debris Rock glaciers 49 5.3 Activity 51 5.3.1 Active Rock Glaciers 51 5.3.2 Inactive Rock Glaciers 54 5.3.3 Relict Rock Glaciers 56 5.4 Age 58 5.4.1 Shoe Lake Rock Glacier (South Cascades) 58 5.4.2 Table Mountain Rock Glacier (Southern North Cascades) 59 5.4.3 Windy Gully Rock Glacier (Southern North Cascades) 61 5.4.4 West Lake Ann Rock Glacier (Southern North Cascades) 61 5.4.5 Mount Stuart Rock Glacier (Southern North Cascades) 62 5.4.6 Courtney Peak Rock Glacier (North Cascades) 62 5.4.7 Gray Peak Rock Glacier (North Cascades) 63 5.4.8 West Oval Lake Rock Glacier (North Cascades) 63 5.4.9 Greater Eastern Cascades 64 v 5.5 Paleoclimatic Implications 65 5.5.1 South Cascades 65 5.5.2 Southern Part of North Cascades 65 5.5.2 North Cascades 66 5.5.2 Greater Eastern Cascades and Regional Correlations 66 SECTION 6 Conclusions 68 SECTION 7 Further Research 70 References 71 Appendix A 77 Vita 79 vi LIST OF FIGURES Figure 3-1: Rock glacier study area in eastern portion of Cascade Range, WA. ....... 18 Figure 5-1: Study area with divisions of rock glaciers by area. ................................. 31 Figure 5-2: South Cascade rock glaciers. ................................................................... 32 Figure 5-3: North Cascade rock glaciers between Stevens and Snoqualmie Pass. .... 33 Figure 5-4: North Cascade rock glaciers in the vicinity of Lake Chelan. .................. 34 Figure 5-5: North Cascade rock glaciers in the vicinity of Washington state highway 20. .......................................................................................................... 35 Figure 5-6: North Cascade rock glaciers in the vicinity of the U.S.-Canada border. .............................................................................................................................. 36 Figure 5-7: Rock glacier latitude in the Eastern Cascades. ........................................ 37 Figure 5-8: Rock glacier head elevations in the Eastern Cascades. ........................... 38 Figure 5-9: Eastern Cascade rock glacier head elevation compared to latitude. ........ 39 Figure 5-10: Rock glacier aspects (in degrees) in the Eastern Cascades. ................... 41 Figure 5-11: Eastern Cascade rock glacier distances east from the Cascade crest. .... 42 Figure 5-12: Rock glacier distance from the Cascade crest compared to head elevation. .............................................................................................................. 44 Figure 5-13: Rock glacier activity by genesis type. ................................................... 46 Figure 5-14: Glaciogenic rock glacier on Star Peak, Sawtooth Range, North Cascades. View is towards the southwest. ........................................................... 47 Figure 5-15: Gelifluction rock glacier on Oval Peak, Sawtooth Range, North Cascades. View is towards the southwest. ............................................................ 49 Figure 5-16: Debris rock glacier on Midday Mountain, North Cascades. View is towards the south. ................................................................................................. 51 Figure 5-17: Active rock glacier on Courtney Peak, Sawtooth Range, North Cascades. View is towards the east. .................................................................... 53 Figure 5-18: Inactive rock glacier on Mt. Stuart, southern North Cascades. View is towards the northeast. ....................................................................................... 55 Figure 5-19: Relict rock glacier on Hock Mountain, North Cascades. ....................... 57 vii LIST OF TABLES Table 4-1: Characteristics of rock glacier activity types. ............................................ 25 Table 5-1: Eastern Cascade rock glacier genesis type comparison. ............................ 45 Table 5-2: Eastern Cascade rock glacier activity type comparison.. ........................... 52 Table 5-3: Eastern Cascade rock glaciers sampled for tree, lichen and weathering rind data. ............................................................................................................... 60 viii ACKNOWLEDGEMENTS The process of writing a thesis is not done alone, and it was the work of many others that contributed to its publication. This research was funded through the Science Honors Research Program at Central Washington University, a valuable and vital program for undergraduate research. Funding for conference presentations was provided by the Office of Undergraduate Research at CWU. Special thanks goes to Dr. Audrey Huerta for being an encouraging mentor throughout the process, and to Dr. Lisa Ely for reviewing my final manuscript. I can’t thank Dr. Karl Lillquist enough for his work as a mentor; he has been positive, engaging and professional throughout the many drafts of this thesis and in fieldwork. Our discussions have engaged my passion for physical geography and the larger world. Finally, I would like to thank my wonderful fiancé Rebecca for supporting me through the entire process, as well as my extended family and colleagues in the SHRP. ix SECTION 1 INTRODUCTION 1.1 Research Problem Rock glaciers are lobate or tongue-shaped masses of rock and ice that form in vacated glacial cirques, or at the bases of steep cliffs in mountain settings. They are common landforms in continental, alpine environs, and have been the topic of study by numerous geomorphologists and glaciologists (Wahrhaftig and Cox, 1959; Thompson, 1962; Humlum, 1988; Krainer, 2006). They occur in many of the world's major mountain ranges, such as the Alps (Krainer, 2005), Rockies (Birkeland, 1973; Janke, 2007; Johnson, 2007), Andes