The Vendian–Silurian succession from a series of boreholes in northeast Germany has been petrographically and geochemically investigated. Evidence suggests that the more northerly Vendian and Cambrian succession was deposited on a craton which became increasingly unstable in Ordovician times. Similarly, the Ordovician-age succession deposited in the Rügen area indicates a strongly active continental margin tectonic setting for the same period. By Silurian times the region was once more relatively tectonically quiescent. Although complete closure of the Tornquist Sea was not complete until latest Silurian times, the major changes in tectonic regime in the Eastern Avalonia/Baltica area recorded from the Ordovician suggest that a significant degree of closure occurred during this time.