Hallingdal. Beskrivelse til kvartærgeologisk landgeneralkart.

Abstract

(forkortet): The present map of the quaternary deposits of Hallingdal was prepared on the general principles reffered to in the summary of Oslo, NGU no. 16, the first map description published in this series and followed by Oppland NGU no. 187. Inland ice movement and wastage: As will appear from the map, glacial striae indicate an inland ice movement in the NW-SE direction of the great valleys. The course of recognizable erratics coincides with this direction. As a consequence of the milder climate heralding the termination of the latest ice age, the firn line rose so that winter's snow decayed during the summer. No ice was accumulated, and the glacier movement subdided; surface wastage set in. The shallower the glacier, the more quickly it melted. Thus, the last vestiges of the inland ice lingered in the valleys and basins. Meltwater streams from the slopes deposited their gravel contents at the surface of the stagnated glacier as well as along the edges and in caves and tunnels. Sedimentation even took place in ice-dammed ponds along the margins of dead glaciers and between isolated ice ridges in the valleys. The gravel material remained after the decay of the ice.