TUNNEL VALLEYS IN DENMARK AND NORTHERN GERMANY

In 1903, Ussing published a small paper entitled "On the outwash plains in Jutland and the theories on their development" in which he advocated that the outwash plains (sander) in Jutland are conical flats and that their sand has not been supplied by rivulets running down the surface of the ice, but was suspended in large meltwater rivers with outlets at the apices of these cones. Thus, the Karup plain should comprise three conical flats with apices: one at Dollerup at the western end of Hald Sø, one near Moselund, and one at Sebstrup. In the second edition of "Geology of Denmark" from 1904 and in a paper from 1907 "On river valleys and terminal moraines in Jutland" Ussing discusses the large valley systems in Jutland and divides them into two groups: 1) the proper late-glacial outlet valleys carved by meltwater in, front of the ice margin and 2) a second group which he calls "fjord valleys". According to Ussing the latter type should be older than the outlet valleys and has been eroded by sub-glacial water streams with outlet right at the apices of the cones. The floor of these fjord valleys lies considerably lower than the surface of the plains, and Ussing therefore advocated the theory that the subglacial streams must have been under pressure in the tunnels and thus been able to force their way uphill, and here the reason could also be found for the uneven profile of the fjord valleys with the many elongated lake basins and the shallow thresholds between them. Ussing gives some examples of fjord valleys, fig. 1. Thus, there appears to be two valleys starting in the region around Manager Fjord towards Viborg and further on to the apex at Dollerup. A third one stretches from Århus through the lakes Himmelbjerg-søerne and the Silkeborg region to the apices of the Moselund and Sebstrup cones. Later on, Madsen (1921) changed the