We may now proceed to connect these statements as to the distribution of icebergs, with the glaciated condition of our continents, with the remarkable fact that the same effects now produced by the ice and the Arctic current in the Strait of Belle-Isle and the deep-current channel off the American coast, are visible all over the North American and European land north of forty degrees of latitude, and that there is evidence that the St. Lawrence valley itself was once a gigantic Belle-Isle, in which thousands of bergs worked perhaps for thousands of years, grinding and striating its rocks, cutting out its deeper parts, and heaping up in it quantities of northern _débris_. Out of this fact of the so-called glaciated condition of the surface of our continents has, however, arisen one of the great controversies of modern geology. While all admit the action of ice in distributing and arranging the materials which constitute the last coating which has been laid upon the surface of our continents, some maintain that land glaciers have done the work, others, that sea-borne ice has been the main agent employed. As in some other controversies, the truth seems to lie between the extremes. Glaciers are slow, inactive, and limited in their sphere. Floating ice is locomotive and far-travelled, extending its action to great distances from its sources. So far, the advantages are in favour of the flotation. But the work which the glacier does is done thoroughly, and, time and facilities being given, it may be done over wide areas. Again, the iceberg is the child of the glacier, and therefore the agency of the one is indirectly that of the other. Thus, in any view we must plough with both of these geological oxen, and the controversy becomes like that old one of the Neptunists and Plutonists, which has been settled by admitting both water and heat to have been instrumental in the formation of rocks. In the midst of these controversies a geologist resident in Great Britain or Canada should have some certain doctrine as to the question whether at that period, geologically recent, which we call the Pleistocene period, the land was raised to a great height above the sea, and covered like Greenland with a mantle of perpetual ice, or whether it was, like the strait of Belle-Isle and the banks of Newfoundland, under water, and annually ground over by icebergs, or whether, as now seems more probable, it was in part composed of elevated ridges covered with snow and sending down glaciers, and partly depressed under the level of ice-laden straits and seas.