Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/85

Rh to Newfoundland remained fast, must have manifested itself in a compression north of that area.

The submarine bank of the Middle Atlantic may also be very briefly considered in this connection. The conception of Haug, who wishes to consider the whole of the Atlantic as an enormous geosynclinal and the mid-Atlantic bank as the beginning of its crumpling, is nowadays regarded by most people as insufficient. The reader need only be referred to Andreé’s criticism. According to the displacement theory, it is the former floor of the rift-valley which was in existence during the period when the Atlantic Ocean was composed of a relatively narrow fracture, which was subsequently filled with sunken margins, shore deposits, and also partly with molten sial. The islands which to-day crown the long bank were certainly formed at this time as fragments of the margins of the rift, an assumption which naturally does not prevent their visible structure being entirely volcanic. During the further continuance of the displacement these infillings still remained together in the middle between the continents. The so-called deep-sea sands, with mineral particles up to 0.2 mm. diameter, which were obviously deposited near the shore-line, but were discovered by the Valdivia Expedition and the German South Polar Expedition under Drygalski in the middle of the ocean, must be regarded as confirming our explanation, for only in this way could all portions of the sea floor have been near the shore at some earlier period.

There is, geologically, much less to be said about the other former continental connections assumed by the theory than for that severed by the Atlantic separation.