Geology of Austria: The Austrian Alps (Eastern Alps) belong to the Alpine mountain system. It consists of various kinds of rock from the Mesozoic Tethys marine strata, which separated the European plate from the African plate (theory of plate tectonics). Slow collision of the plates in a north-south direction caused multiphase mountain building (mainly in the Cretaceous and Tertiary periods), inner buckling and superimposition of the various series of rocks (polycyclic relief).
Deeper-lying levels of the Alpine range have been revealed by erosion (e.g. "Tauernfenster" window), allowing a more precise analysis of the internal mountain structure. After the end of the principal phases of mountain formation, the basins developed in the Alpine range (Vienna Basin, Styrian Basin, Mur-Muerz channel, Klagenfurt Basin, Lavanttal Basin). The most important is the Vienna Basin, with its rich petroleum and natural gas deposits in the sedimentary rock.
The Waldviertel and Muehlviertel regions ( Bohemian Massif) form the Austrian share of the Variscan mountain system; today this granite tableland represents the roots of a Palaeozoic mountain system with the oldest rock formation in Austria, the Bittesch gneiss (1.38 billion years).
Between the Bohemian Massif and the Alpine range to the south lie the plains of the Molasse Zone; these plains are composed of the sediments of the latter. In the course of later mountain building phases (Tertiary) southern parts of the molasse zone were superimposed by the Alpine range. The Alps and the molasse zone were last shaped by the consolidated thick ice cover during the Ice Age.
Literature#A. Tollmann, Geologie von Oesterreich, 3 vols., 1977-1989; R. Oberhauser, Der geologische Bau Oesterreichs, 1980.