Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/50

26 of the earth in its adjustment to the new ellipsoid of rotation. But it is a mistake to believe that only a difference of degree exists between such alterations of level and the submergence of a continent to the deep sea floor. For the last case would involve the changing-over of the upper frequency maximum of the earth’s crust to the lower, and we should be in need of a physical cause for the favouring of the level of the ocean floor and the absence of the intermediate layers; which is not forthcoming (see ). The partisans of the permanence doctrine have thus at their disposal good arguments against the doctrine of the submerged bridging-continents.

But since they start from the obvious assumption that the continents have always lain where they do to-day, the advocates of the permanence theory arrive at false conclusions from their accurate premises when they explain: “The great ocean basins are permanent features of the earth’s surface, and they have existed, where they are now, with moderate changes of outline, since the waters first gathered.” When we bring into consideration horizontal drift movements of the continents, we can only uphold this principle so far as to agree that the total areas of the continental blocks and of the ocean floors, except for the compression of the former in the course of time,