The main geological units in Europe are shown in Fig. 1 based on a modified tectonic map, prepared by Berthelsen (pers. comm.). The area of the Federal Republic of Germany where the DEKORP studies took place, is marked and stretches about 900 km N-S and 300 km E-W. It covers the eastern end of the 1000 km long Hercynian-Alleghanian fold belt on the North Atlantic margin, i.e. the Appalachian-Mauretanides-European Variscides between the Caledonides in the north and the Alps in the south.