Abstract
The investigations of the glacial sequence in the Randers area include mapping of the surface layers, study of bore profiles and detailed examination of outcrops, concentrating on the determination of transport directions in the deposits.The following stratigraphic succession has been established:Highest: NE tillTebbestrup Formation (melt water deposits)SE tillHaldum Formation (melt water deposits)Lowest: NE tillThe two uppermost units can with certainty be referred to Weichselian. Arguments are presented that the three lowermost units are of Saalian age.The origin of the sequence is discussed. The highest hills in the area (Ølst, Lysnet) were probably formed by the Saalian ice from the NE, since they appear to have influenced flow directions during the deposition of the Haldum Formation. This formation is considered to represent a sandur formed in front of the advancing ice from the SE. In the Weichselian, prior to the formation of the Tebbestrup Formation, the landscape obviously had a varied relief. The formation which infills the lower parts of this landscape is considered as a sandur, formed in front of the advancing ice from the NE. This sandur, together with the prominent hills from the Saalian, formed the substrate for the ice from the NE. This ice modified, but did not destroy the old hills.
Highlights
Geological mapping of the Quaternary of the Randers map sheet has been carried out by a group from the Department of Geology, Aarhus University, in cooperation with the Geological Survey of Denmark
In the two first-mentioned publications a hypothesis is put forward, based on the first results of the mapping, which suggests that landscape remnants from the Saalian glaciation occur preserved within the areal extent of the Weichselian glaciation
The hypothesis is based on the following relations: The landscape in the Randers area is characterised by a plateau, dissected by large valley systems which surrounded for example, the notable hills at 01st and Lysnet (Fig. 1)
Summary
The hills at 01st and Lysnet , consisting of Eocene clay with tuff horizons (Nielsen , 1973) and strongly disturbed by glacial tectonics, occur as the highest parts of a glacial terraine older than the melt water deposits of the plateau landscape. 2 the plateau landscape around Randers Fjord and the Gudena valley consist of widely developed melt water deposits covered by till, and Tertiary clay makes up most of the prominent hills at 01st and Lysnet. The directions of ice movement has been investigated by measuring deformation structures (plunge of fold axes and dip directions of thrust planes) and partly by fabric studies of tills; both the macrofabric method and the radiography method for microfabric investigation (Liboriussen, 1973) have been used The results of these investigations for a series of exposures (localities given in Fig. 1) are given below.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have