Document Type

Thesis

Date of Degree Completion

Spring 2013

Degree Name

Bachelor of Science

Department

Geological Sciences

Committee Chair

Karl Lillquist

Second Committee Member

Lisa Ely

Third Committee Member

Audrey D. Huerta

Abstract

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.

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