Rock glaciers on Prins Karls Forland. II: GPR soundings and the development of internal structures

Internal structures in four rock glacier's in the continuous permafrost zon e on the island of Prins Karls For-land, western Svalbard (78 degrees 50'N, 10 degrees 30'E), were studied utilizing ground penetrating radar (GPR). A comparative study was performed on the Broggerbreen rock glacier close to Ny-Alesund, about 50 km to the east. The bedrock interface was visible on s ome GPR profiles. Further, the length profiles: revealed a system of reflec tors that was comparable between the different rock glaciers. A layering st ructure parallel with the surface was visible in the: upper part of the tal us cones above the rock glaciers, while further down towards the rock glaci ers these reflectors started to slant up against the surface slope. This in clination of the layers prevailed towards the fronts, although a more irreg ular pattern was discernible in the frontal part of some of the rock glacie rs. The layering structure is probably formed by mass movements of higher m agnitude, covering either snow patches or the active layer above supersatur ated permafrost. We suggest that the structural development along the rock glaciers is caused by an accumulation gradient along the talus-cone/rock-gl aciers system, causing differences in vertical velocity along a layer. Copy right (C) 2000 John Wiley & Sons, Ltd.