BASIC PALAEOGEOGRAPHY OF GONDWANALAND DURING THE LATE PALAEOZOIC AND MESOZOIC ERAS

Abstract

The mighty sequences of late Palaeozoic and Mesozoic continental sediments characteristic of Gondwanaland are reviewed and interpreted palaeoclimatically. The glacial and succeeding beds are not susceptible of explanation on the simple hypothesis of a “Permo-Carboniferous” refrigeration—actually the glacial episode had passed in western Argentina before it began in Australia and. climates in western Gondwana were warming up after glaciation while those in the east were cooling towards refrigeration. From the Carboniferous period until the Jurassic, facies divisions within the continental rock sequences cross the time divisions progressively from weat to east. The palaeoclimatic data are plotted on a series of restorations of Gondwanaland that had been independently derived several years before from a study of the pattern of major sub-oceanic ridges which had suggested successive positions for the reassembly on the globe. The data so plotted are found to fall into climatic girdles consonant with latitude that are precisely similar to the major girdles—frigid, cold, temperate and tropical—of the present day. This agreement of the palaeoclimatic data with modern conditions is of such an order as to verify both the accuracy of the reassembly and the positions for it deduced previously from the pattern of mid-oceanic ridges.