![Sample our Earth Sciences journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5930/TOC-Subject-Sample-2021-Earth-Sciences.jpg"})
Abstract
Two new concepts relating to rock glaciers are defined: the rock glacier appearance level (RAL) and the rock glacier initiation line altitude (RILA). The RAL may be regarded as an analogy to the glaciological concept glaciation level (GL) and indicates a critical summit altitude below which no rock glaciers occur. The RILA is a measure of the rock glacier head altitude and is situated below or at the local equilibrium line altitude (ELA) of glaciers.
RAL and RILA have been mapped in a 370-km2 peninsula on the western coast of Disko, central West Greenland (70°N), where rock glaciers are numerous. Experience from this mapping indicates that when RAL and RILA values are compared with GL and ELA values, respectively, (1) different rock glacier generations may be differentiated and (2) rock glaciers belonging to the same generation may be differentiated as to being glacial or periglacial features. From this, some inferences as to their probable genesis may be drawn. The accumulation of snow appears to exercise control on the distribution of glacial rock glaciers, whereas temperature probably is a critical control on periglacial rock glaciers. Finally, it is suggested that further studies on RAL and RILA surfaces, supplemented by climatic measurements at selected sites, may yield information on past and present climate, in much the same way as from studies on past and present GLs and ELAs.