Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/124

98 contradiction of observations among one another has absolutely crippled the development of palæoclimatology. All the above-quoted attempts to trace the position of the poles continuously throughout the geological succession must be wrecked on this rock.

The riddle of the Permo-Carboniferous glacial period now finds an extremely impressive solution in the displacement theory: directly those parts of the earth which bear these traces of ice-action are concentrically crowded together around South Africa, then the whole area formerly covered with ice becomes of no greater extent than that of the Pleistocene glaciation on the northern hemisphere. It is no longer merely a question of simplification which the displacement theory provides, it rather affords the first possibility of any explanation whatsoever.

In view of the great importance of these facts to the question of the correctness of the displacement theory, we will, in the following pages, attempt to take into account the most weighty of the remaining evidences of climate from the period under consideration, and see whether they adapt themselves, on the basis of the displacement theory, to a definite orientation of the climatic belts.

Let it be supposed that we have to reckon from the beginning that this very reduced ice-cap never existed in its complete extent, but has appeared successively in the different countries by the wandering of the South Pole. To be sure, the determination of the age at most places is not so exact that these relatively trifling differences of time can be safely detected geologically. But this time-displacement has also already been assumed on the geological side. Thus L. Waagen suggests that the beds with Glossopteris lie above the