The Geology of the Baltic Sea is characterized by having both areas located at the Baltic Shield of the East European Craton and the Danish-North German-Polish Caledonides. There is a distinction between what is the current Baltic Sea depression, formed in the Cenozoic Era, and the much older sedimentary basins whose sediments are preserved in the zone. Although glacial erosion has contributed to shape the present depression, the Baltic trough is largely a depression of tectonic origin that existed long before the Quaternary glaciation.