Ice Movements and Till Stratigraphy in the Gudbrandsdal Area. Preliminary Results

Abstract

The authors have previously described two localities with sub-till sediments from a Weichselian interstadial in the Gudbrandsdal (Bergersen & Garnes 1971). Based on studies of striae and tills, the last glaciation is preliminarily divided into four phases. Most of the till in the investigated area is believed to have been deposited during the two first phases, A and B. During phase A the glaciers advanced from high mountain areas. Entering the valleys, the ice gave rise to ice-dammed lakes, the deposits of which are found as sub-till sediments. Phase B was the main phase of the inland ice with an ice divide northwest of the Gudbrandsdal. Later, during phase C, the ice divide was situated above the central part of the Gudbrandsdal. Consequently, the glacio-geological processes in the investigated area were modest during both phase C and the deglaciation period, phase D. During the latter, a gradual transition from active to stagnant to dynamically dead ice took place. Simultaneously the meltwater drainage changed from being mainly supraglacial to lateral/englacial and finally subglacial.