phenomenon at all, but a local affair which on the face of it had nothing to do with the pole. For investigation has disclosed that instead of emanating from the

Map showing the glaciated area of North America—the arrows indicating the direction of ice movement—Chamberlin and Salisbury. pole southward, it proceeded from certain centres, descending thence in all directions, north as much as south. Thus there was a centre in Norway in 65° N. lat. and another in Scotland in 56° N. In North America there were three—the Labradorian in latitude 54° N., the Kerwatin to the northwest of Hudson's Bay in latitude 62° N., and the Cordilleran along the Pacific coast in latitude 58° N. On the other hand, northern Siberia, the coldest region in the world, was not glaciated. That the ice flowed off these centres proves them to have been higher than the sides. But we have