Rock glacier dynamics in marginal periglacial environments

摘要

Vertical electric sounding, bottom temperature of winter snow cover (BTS) and ground thermal measurement, debris surface analysis and a differential global positioning system (DGPS) survey were performed on the Posets rock glacier (Pyrenees) between 2001 and 2008. High precision records of horizontal and vertical movements of the rock glacier were measured using a DGPS on ten steel rods. Total and annual average displacements and thickness changes for each control point were derived from the field survey. Horizontal and vertical displacement rates in different sectors of the rock glacier were compared, and these compared with thermal, structural and morphological maps. The inferred surface deformation was characterized by extensional and compressive flows in which two dynamic types were found. The first type of movement is defined by the slide and flows related to the existence of an ice body over the frost body. The second dynamic type involved the displacement generated by deformation of the frozen body. The study attempts to understand the surface movement and dynamics of rock glaciers in marginal cold environments and their usefulness as environmental geoindicators.