Portland State University. Department of Geology
Andrew G. Fountain
Term of Graduation
Date of Publication
Master of Science (M.S.) in Geology
1 online resource (viii, 129 pages)
Rock glaciers are flowing geomorphic landforms composed of an ice/debris mixture. A uniform rock glacier classification scheme was created for the western continental US, based on internationally recognized criteria, to merge the various regional published inventories. A total of 2249 rock glaciers (1564 active, 685 inactive) and 7852 features of interest were identified in 10 states (WA, OR, CA, ID, NV, UT, ID, MT, WY, CO, NM). Sulfur Creek rock glacier in Wyoming is the largest active rock glacier (2.39 km2). The mean area and elevation for active and inactive rock glaciers are 0.18 km2, 3384 m; and 0.20 km2, 3072 m, respectively. Mean elevation increases from the northwest in Washington State, ~1670 m to the southeast, in Colorado ~4100 m. Rock glaciers are found in climates with similar temperatures, ±1oC, and drier ~ 50% compared to alpine glaciers. Few rock glaciers occur in locations where precipitation exceeds 1200 mm. The total volume of ice in rock glaciers in the western US is about 6.99 ± 0.278 km3, which is about half of that contained in the glaciers, 12.37 km3.
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Trcka, Allison Reese, "Inventory of Rock Glaciers in the American West and Their Topography and Climate" (2020). Dissertations and Theses. Paper 5637.