GLACIOLOGY AND GEODYNAMICS

A LARGE body of geological evidence about the Ice Ages of the Pleistocene exists, indicating a pattern of major glacial and inter-glacial periods, minor advances and withdrawals of ice cover and associated climatic fluctuations. This has been extensively studied. It is only recently, however, that the time-scale of this pattern has become established, and even now there seems room for dispute about such major questions as the contemporaneity of the Pleistocene glaciations in different parts of the globe. Lack of information has never deterred geophysical speculation, and the past existence of ice caps much greater than those known to-day clearly calls for an explanation, particularly since in the more remote past, these ice caps appear to have been formed in what are now temperate or subtropical regions. At present, one school of thought holds that world-wide climatic fluctuations due to changes in the intensity of the solar radiation must have been responsible for the ice ages of the past. The other school, with which we are concerned in this review, takes the uniformitarian view that the climatic zones have always, on average, been as they are to-day. The glaciations are then explained by supposing that the region in question was situated at one of the poles in the past. The adherents of this school, then