Supposed area‐wasting of the Weichselian ice sheet in Denmark

• Published in: Boreas
• Main Author: MARCUSSEN, IB
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1977
• Subjects: Ice Sheet
• Online Access: http://dx.doi.org/10.1111/j.1502-3885.1977.tb00345.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1502-3885.1977.tb00345.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1502-3885.1977.tb00345.x

The deglaciation at the end of the Weichselian in the Danish area has previously been considered to occur as a frontal wastage. Since the glacier ice was assumed to be debris‐free, the wasting should be characterized by outwash plains and successions of end‐moraines. The almost complete lack of sandur plains in the eastern part of the area and indications from recent investigations of widespread occurrence of flow till justify a re‐evaluation of the mentioned deglaciation model. Two morphological features have a general occurrence: the plains and the ‘tunnel’ valleys. The plains appear stepwise in the landscapes, and are frequently limited by steep slopes. Topmost is a subcircular kame‐like hill. Sedimentologically, the plains mainly consist of melt water deposits, and the scattered occurrences of till are interpreted as flow till. The plains continue from the open landscape into the ‘tunnel’ valleys where they appear as terraces. These features are considered to have been formed during the deglaciation. The almost horizontal surface of the ice sheet over large areas caused a sensitivity to changes in the climate. The wasting of the ice may therefore be expected to affect large areas almost simultaneously. On the assumption that the ice contained debris, an increasing amount of clastic matter was released on the ice surface. This material was concentrated in the depressions. If such a depression perforated the ice, the content of sediments settled on the substratum and a plain was established. During continued wasting the thickness of the ice decreased and the depressions were enlarged. They assumed the character of sandur plains. As still larger areas of these supraglacial sandurs rested on the basement the successive lower situated plains were formed. The latest ice was preserved where the ‘tunnel’ valleys are situated to‐day.