Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/125

Rh boulder-clay in Africa and India, below in Australia. “Hence it is quite unambiguous, that the ice spread its mantle at an earlier period in India and South Africa, but at a later in Australia. We can thus establish a Carboniferous glacial epoch for Indo-Africa, for Australia a Permian.” In Argentina also, according to Gerth, the sandstones with Glossopteris and Gangamopteris lie above the glacial deposits there. From this it might not be improbable that the most westerly traces found in Brazil, Togoland and the Congo had their origin in the lower Carboniferous. Since, again, ice phenomena are known in the Lower Devonian of South Africa, the South Pole might have moved between the Lower Devonian to the Lower Carboniferous from Cape Colony to Loanda, then reversed, it would have moved in the Upper Carboniferous over from South Africa to the southern point of India and in the Permian to Australia. The corresponding path of the North Pole was completely in the Northern Pacific, and thus could produce no traces of ice worth mentioning. We shall now see how the remaining climatic evidences fit in with this. The most important are recorded in Fig. 17.

Let us first consider the distribution of the Glossopteris flora. The climatic character of this flora has been variously explained; to some it is a polar tundra-flora, to others it is only a temperate one. It will be generally admitted that it belongs to a colder climate than the normal tropical flora of the Carboniferous, which is yet to be described. But in my opinion we