648 MOHO DISCONTINUITY The thickened orogenic crust may be thinned by syn- to post-orogenic extension driven by mantle convection, which creates new continental rifts and oceanic basins This brief overview demonstrates that the Mohodiscontinuity is a sensitive indicator for the detection of past and recent geodynamic processes Main Tectonic Units of the European Continent Present-day Europe forms the western part of the large continental Eurasian Plate It is bordered in the east by the mountain belt of the Urals and in the north and west by the Atlantic Ocean, which opened in the Triassic The southern border of Europe is formed by the Mediterranean Sea, the Black Sea, and the Caspian Sea (Figure 3) The growth of the European continent started in the northern region of the Baltic Shield, and the European crust becomes younger and younger from north to south and from east to west Five main tectonic domains can be distinguished: (1) The East European (Russian) Platform and the Baltic Shield, the north-western part, were formed during Precambrian times, 3.6 Ga to 660 Ma (see Europe: East European Craton) The western margin of the East European Platform is formed by the complexly structured Trans-European Suture Zone (TESZ), which separates the Variscan mobile belts of Central Europe from the stable platform of Eastern and Northern Europe This suture zone extends over 2000 km from the North Sea down to the north-western Black Sea (2) The north-western margin of the Baltic Shield is marked by the Caledonide Orogen, which was formed during the Late Silurian to Early Devonian (see Europe: Scandinavian Caledonides (with Greenland)) The Caledonides continue into northern parts of England and Ireland (see Europe: Caledonides of Britain and Ireland) (3) On the eastern side of the East European Platform, the Uralian Orogen (380–250 Ma) marks the tectonic boundary Figure Main tectonic units of Europe The position of the crustal cross sections described in this paper is marked by red lines Modified from Gee and Zeyen (1996)