Thursday, July 10, 2008

Rock Glacier: The First View

rock glacier view
sign view
As you leave the Bristlecone pine grove, you hike up a lumpy, rocky glacial moraine and fairly shortly come in view of the rock glacier sitting in the cirque on the north side of Wheeler Peak.

All or most online references I could find to the active glacier on Wheeler Peak cited the NPS website. As the sign above from the park shows, there is a glacier and a rock glacier on Wheeler Peak. This link, page 10, states that the rock glacier was active until 1955, although it doesn't go into any details. I'll get into the convoluted history of the glacier and rock glacier in another post. This USGS Professional Paper, 2002, page 9, lists a glacier on Wheeler Peak, one that has an area of 0.2 square kilometers. The authors don't say whether they are referring to the glacier, the rock glacier, or both.

MOH and I did not make it all the way up to the glacier, which is a small cirque glacier with hanging glacier above it, or possibly just a cirque glacier (see these types of glaciers). At the time of field work done by Osborne and Bevis (2001) - over a period of 10 years in the 1990's - the glacier was definitely active, being perennial, deforming under it's own weight, and showing a bergschrund. As for the rock glacier itself, there are numerous definitions and descriptions of rock glaciers, some of which include rock glaciers that don't have any ice anymore - either interstitial to the rocks making up the rock glacier (ice-cemented) or below the rocks of the rock glacier (ice-cored).

rock glacier closeup A closer view of the rock glacier shows that the upper portion has a steep face that rises above the lower portion (behind the talus slope seen on the right side of the photo). The rock glacier has snow or ice fields on both sides of it, and snow, ice, and the small glacier behind it at the base of the cirque headwall and upward into the larger talus-ice chute (seen somewhat in the above photo). The small glacier feeds into or grades into the rock glacier at its base.

As I said, I'll get into a few more details in a later post, and will have considerably more references.

References:
Krimmel, R.M., 2002, Glaciers of the western United States, with a section on Glacier retreat in Glacier National Park, Montana by Key, C.H., Fagre, D.B., and Menicke, R.K., Glaciers of the conterminous United States (J-2) in in Williams, R.S., Jr., and Ferrigno, J.G., eds., Satellite image atlas of glaciers of the world: U.S. Geological Survey Professional Paper 1386-J (Glaciers of North America), 405 p., ISBN 0-067-98290-X.

Osborn, G., 1990. The Wheeler Peak cirque and glacier/rock glacier. Unpublished report prepared for the Great Basin Natural History Association. University of Calgary Dept. of Geology and Geophysics.

Osborn, G. and Bevis, K., 2001, Glaciation in the Great Basin of the Western United States: Quaternary Science Reviews 20, 1377-1410.


Wheeler Peak is inside Great Basin National Park

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