Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/27

Rh the other (during the transition from the Chalk to Tertiary) this long connecting portion was more and more folded together through the continuous gradual approach of India to Asia and constitutes to-day the mightiest mountain folds of the earth, the Himalayas and the numerous folded ranges of the high lands of Asia.

In other regions also the displacement of the blocks occurs in causal connection with the origin of the mountain systems. By the westward drift of the two Americas their anterior margin was folded together to form the mighty range of the Andes (which stretches from Alaska to Antarctica) as a result of the opposition of the ancient well-cooled and therefore resistant floor of the Pacific. A similar case is that of the Australian block, which includes New Guinea since it is only separated therefrom by a shelf. The recent high ranges of New Guinea occur on the side which is anterior with reference to the movement; as our map shows, this direction of movement was different before the break from Antarctica, for the present east coast was then the front side. Next the mountains of New Zealand lying immediately in front of this coast were folded, later becoming detached as festoons of islands by the altered direction of movement and then lagging behind. The present cordilleras of East Australia originated in a still older period; they were formed (at the same time as the more ancient folds, “Pre-cordilleras,” in South and North America, which are the foundations of the Andes) on the front margin of the continental masses, which were drifting as a whole before the separation.

Besides this westward wandering we also see to a large extent a striving towards the equator of the continental blocks. With this is connected the formation of the great Tertiary belt of folding stretching from the