Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/183



far back as 1878, A. Heim had developed in his classical paper, “Untersuchungen über den Mechanismus der Gebirgsbildung,” the idea that the great chains of folded mountains originated in a considerable compression of the earth’s crust. This doctrine was amplified by the discovery of the imbricated sheet folds in the Alps which indicated a still more powerful compression.

According to this new conception, to which he assented, A. Heim now calculated the compression of the Alps, which he had first estimated at a half, to be from a quarter to an eighth. Later, Ampferer assumed flow-movements of the deeper layers which, directed towards each other from both sides, pass downwards under the mountain chain and carry the upper beds passively along with them (under-currents). Koszmat has quite recently referred to the curvature of the mountain chains, and their fan-shaped association at many places. This appears to him only explainable by great horizontal displacements; “many features in the relief and structure of the earth seem to make it certain that an explanation of mountain-building must take into account enormous tangential movements of the crust. This conception is in itself almost identical with that of the displacement theory,