into solid ice. Imagine all this on an enormous scale! Not over an area of a dozen or a hundred, or even a thousand square miles, but over an area as large as Europe and Australia combined, then we have a picture of what is happening over the length and breadth of Antarctica! The ice thus accumulated from snowfall, thus consolidated from loose snow into solid ice by pressure, gets pushed ultimately into the sea. Let me indicate what happens by referring for a moment to a phenomenon with which all of us are familiar. A snowstorm whitens all the country round and every roof has a coating of snow some six inches thick. The snow gets bound together and remains a more or less solid covering on the roof, till one day it slips off from various causes in irregular pieces, all about six inches thick and perhaps several feet across, and crashes down on the roadway beneath. But if the eaves of the roof dipped into water at that level, then this great sheet of icy snow would, when slipping from the roof, float off on the surface of the water. The floating sheets of icy snow—"floating ice islands"—would be of various areas, but they would all be flat-topped, and of a uniform thickness of six inches, the sides would be more or less perpendicular, and the greater part of the thickness would be below the surface of the
