USA

Rock glaciers of the northern Absaroka and Beartooth Ranges have not previously been described. Six-hundred and sixty rock glaciers were hand digitized in a GIS and evaluated using 11 distributional characteristics. Beartooth rock glaciers were found to occur at higher elevations, receive more precipitation, and were subjected to colder temperatures. Additionally, logistic regression analysis was used to examine the predictive strength of the 11 descriptive parameters on rock-glacier activity. Elevation and average annual maximum temperatures were most strongly correlated with activity. Results were used to make inferences about permafrost distribution which coincided with estimates from previous studies. Finally, movement rates of four rock glaciers within the Black Canyon Basin of the Beartooth Mountains were estimated using photogrammetric techniques over a 51-year period. While movement rates were consistent with those determined in other Rocky Mountain locations, much of the results were inconclusive. Increased movement of the East Grasshopper rock glacier may be the result of increased glacier subsidence, while ₁uphill' movement of the Beartooth rock glacier may be indicative of rock-glacier subsidence.