Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/66



sharp control on our supposition that the Atlantic is formed of an enormously expanded rift, the margins of which formerly directly adjoined each other, is exercised by a comparison of the geological structures on both sides; for it is to be expected that folds and other structures, formed before the separation, will be continuous from one side to the other, and their terminations on both sides of the ocean must lie exactly in such a position that they appear as immediate continuations in the reconstruction. Since the reconstruction itself is a very restricted one, on account of the well-marked course of the continental margins, and leaves no room for adjustment to fit this requirement, we are dealing with a quite independent criterion which is of the greatest value for the estimation of the accuracy of the displacement theory.

The Atlantic rift is broadest in the south, where it first broke open. Its width amounts here to 6220 km. Between Cape San Roque and the Cameroons there are 4880 km., between Newfoundland Bank and the British shelf 2410 km., between Scoresby Sound and Hammerfest but 1300 km., and between the margins of the shelves of North-East Greenland and Spitsbergen probably only from 200 to 300 km. Here the split appears to have taken place in quite recent times.

Let us commence the comparison in the south. In