Remote sensing as a tool for observing rock glaciers in the Greater Yellowstone Ecosystem
Fairweather, I.S. and Hager, S.A.
in: A. Wondrak Biel, ed., Greater Yellowstone Public Lands: A Century of Discovery, Hard Lessons, and Bright Prospects: Proceedings of the 8th Biennial Scientific Converence on the Greater Yellowstone Ecosystem, October 17-19, 2005, Mammoth Hot Springs Hotel, Yellowstone National Park. Yellowstone Center for Resources, Yellowstone National Park, Wyoming, USA
Rock glaciers are found in and adjacent to Yellowstone National Park, primarily in the high elevation regions of the Absaroka and Beartooth mountain ranges. One rock glacier that has been intensely studied is the Galena Creek Rock Glacier, located on the east boundary of the park in the northern Absaroka mountain range. A rock glacier's movement and behavior is characterized by rock and other debris overlying and embedded within the ice mass. These glaciers are found in alpine regions at the foot of rock faces with large supplies of talus and debris. The debris acts as insulation for the ice and prevents solar radiation from ablating the ice surface, allow- ing rock glaciers to exist at lower elevations and latitudes than regular glaciers. Rock glaciers deform and flow similarly to ice glaciers, but possess some unique characteristics. They are an important mechanism for transport- ing masses of rock debris in cold, continental, non-glacierized mountain environments. They are also natural storage mechanisms for water, providing watershed runoff in late summer months. Locating and studying these features can be arduous due to their positions at high elevations and rugged terrain. As a result, remote sensing is a superb tool for observing and studying these glaciers. Hyperspectral and multispectral imagery are used to delineate their geographic extent as well as the composition of the debris overlying the ice mass. The distinct spectral signature of ice can be used to extract regions of bare ice at the head of a glacier. Radar images can also be used to reveal rough surface texture and create DEMs for delineating cross-glacier profiles as well as terminal and lateral moraines. Using the geographical extent and height of a glacier (from the topographic profiles), vol- umes are calculated to deduce water storage. Rock glaciers can also be used as climatic indicators for long-term monitoring.