Geology

The Southern Alps throughout their length are composed of Upper Paleozoic to Mid-Mesozoic sediments, greywackes, and argillites, and their transformed (metamorphosed) underlying equivalents, the schists of the western side of the main divide. They have been deformed by two periods of diastrophism which gave the rocks their complicated fold-structures and generally steep attitudes. The second deformation, which is probably still in progress, was a block-faulting and tilting which reached an extreme in the Alps, and produced the basis of the present topography. The maximum tilting was to the west along the Alpine Fault where schist underlying the eastern greywacke is now exposed, implying a displacement of tens of thousands of feet.