Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/86

62 Madagascar consists, like its neighbour Africa, of a platform of folded gneiss with a north-easterly direction of strike. On both sides of the line of fracture identical marine sediments have been deposited, which show that both areas have been separated since the Trias by a flooded trough fault, a fact which is also demanded by the land fauna of Madagascar. But according to Lemoine, two animals, Potamochœrus and Hippopotamus, had immigrated from Africa in the Middle Tertiaries, when India had already moved away. These animals, Lemoine thinks, could at the most only swim an arm of the sea of 30 km. breadth, whilst the Mozambique Channel is now quite 400 km. wide. Thus the block of Madagascar must have broken loose from Africa beneath the sea after this period, which explains the great start India had, compared with Madagascar, in the displacement towards the north-west.

India is also a flat platform of folded gneiss. The folding is still visible to-day, in the very old Aravali mountains in the extreme north-west (on the edge of the Thar Desert) and in the similarly very old Korana mountains. According to Suess, the strike in the former is N. 36° E.; in the latter, to the north-east. Both strike directions thus correspond to those of Africa and Madagascar, especially with the slight rotation of India required in the reconstruction. In this context a somewhat more recent but still Mesozoic folding occurs also in the Ghats of Nellore or in the Vellakonda mountains, the strike of which is from north to south, and which agrees very well with the likewise later north-south trend-lines in Africa. The occurrence of diamonds in India is linked with that of South Africa. It is assumed in our reconstruction