Mon Oct 29 2007 at 18:36:26
A rock glacier (AKA a block stream) is an ill-defined beast. It is, in essence, a pile of rocks that looks or acts like a glacier:
"...a tongue-like or lobate body, usually of angular boulders, that resembles a small glacier, generally occurs in high mountainous terrain and usually has ridges, furrows, and sometimes lobes on its surface, and has a steep front at the angle of repose.
--
N. Potter Jr.,
1972 Ice-cored rock glacier, Galena Creek, northern Absaroka Mountains, Wyoming. Geological Society of America Bulletin, 83, 3025-3057.
Rock glaciers commonly occur along the bases of cliffs or on the floors of cirques. They look like giant lobate lava flows made of chunks of rock, often containing boulders measuring meters in diameter. The steep sides and front of these mounds may be up to 60 meters high (~180 feet). The study of rock glaciers is only about 100 years old, the first papers published on the phenomenon appearing in the 1900-1910s. But these formations appear around the world, particularly in North America (the American Cordillera), the Alps, and central Asia.