Periglacial Landforms and Processes in the Southern Kenai Mountains, Alaska

摘要

The distribution and characteristics of periglacial landforms in the southern Kenai Mountains, Alaska, were investigated during 1979 and 1980. The principal area of study was a 1300-m-high mountain mass that stood as a nunatak during the last general glaciation. Periglacial features in the area include gelifluction lobes, nivation hollows, cryoplanation terraces, tors, a string bog, and such patterned ground as sorted circles, sorted polygons, earth hummocks, sorted steps, sorted stripes, and small ice-wedge polygons. Ground temperature measurements indicate that permafrost exists in only isolated patches but may have recently been much more extensive. The sorted polygons, cryoplanation terraces, and nivation hollows are relict features that have been inactive for a considerable time. The turf-banked sorted steps and large gelifluction lobes probably were active until the recent thawing of permafrost. Cryofraction and frost sorting still are vigorous, active progresses. Finely jointed bedrock, a previous colder environment, and long exposure in the absence of glacial ice has allowed periglacial processes to be the dominant surface agents both in the principal study area and in similar areas along the western side of the Kenai Mountains. Keywords: Gelifluction, Geomorphology, Kenai Mountains, Nunatak, Patterned Ground, Periglacial, Permafrost.