Some Problems of Arctic Geology.¹

Abstract

FORMER ARCTIC CLIMATES. IN a summary of the geological history of the Arctic Ocean (ante, p. 301) it was remarked that in Silurian times the water was warmer than it is at the present day; and there is no doubt that the climate of the Arctic regions has varied greatly. According to the belief generally accepted there have been periods when the climate of the northern hemisphere was so severe that an ice sheet extended from Ireland to Siberia, from the Thames Valley to the North Pole; and then at other times, as the whole earth enjoyed the doubtful benefits of a tropical climate, Greenland's now icy mountains were bordered by a coral strand. This view of the great variation of Arctic temperature has been so widely held that it has exercised a very great influence on theories of faunal migrations and on the former climates of the world. The volumes which summarise the results of the Challenger expedition show to what an extent some of the latest speculations as to climatic change have been influenced by this theory; for in that work Dr. Murray strongly advocates Blandet's suggestion that in late Palæozoic times there was “over the whole globe an almost complete equality in the distribution of light and heat” due to the “very much greater size of the sun in the early stages of the earth's history.” And this bigger Palæozoic sun was assumed in order to explain the fact that “the Arctic Ocean was a coral sea in Carboniferous times.”