Rock glaciers of the Beartooth and northern Absaroka ranges, Montana, USA

Six hundred sixty‐one rock glaciers in the northern Absaroka and Beartooth Ranges of south‐central Montana were digitized and evaluated using geographic information systems technology and an array of topographic and environmental parameters. Beartooth rock glaciers are larger, occur at higher elevations, receive more precipitation, and are subject to lower temperatures than northern Absaroka rock glaciers. Elevation is strongly correlated with rock glacier activity. Comparative analysis of these adjacent mountain ranges indicates that Beartooth geomorphic landscapes are shifting from predominantly glacial to periglacial regimes, and that the northern Absarokas have largely completed this transition. Because glaciers are declining in response to climate warming, rock glaciers could soon become the most important source of ice in the region. View the dataset associated with this article. Read the thesis associated with this article

Sand deserts during glacial maximum and climatic optimum

The past 20,000 yr have witnessed tremendous climatic changes, a glacial maximum at about 18,000 yr BP and a climatic optimum centred on about 6,000 yr BP, both of which mark extreme situations for the Quaternary. This paper attempts to show that active sand dunes were extensive 18,000 yr ago. Conversely, it seems that sand dunes were generally dormant 6,000 yr ago. Thus the former textbook concept1,2 of an arid climatic optimum and a pluvially active glacial maximum is reversed