On the Later Physiographical Geology of the Rocky Mountain Region in Canada, with Special Reference to Changes in Elevation and to the History of the Glacial Period.1

Abstract

DR. G. M. DAWSON has been engaged continuously for seventeen years in geological exploration of the Western Territories of Canada, including the country from Lake Superior to the Pacific; and in the paper above named he summarizes the history of the successive deposits and earth-movements which have built up the mountain ranges of the West, and the relations of these to the geology of the great plains to the eastward. He devotes special attention to the Glacial age, and concludes that the drift phenomena of the plains belong to a period of submergence, and that in the extreme period of glaciation there were great glaciers on the Cordillera on the west, and the Laurentian axis on the east, with a vast internal sea between. He is thus entirely opposed, as far as North America is concerned, to the idea of a Polar ice-cap or a great continental glacier flowing down the interior plateau of the continent, and he resolves the phenomena of the ice age into the operation of huge mountain glaciers and floating ice.