CONTINENTAL SHELF, the term in physical geography for the submerged platform upon which the continental areas stand in relief. The volume of the hydrosphere is a little too great for the true ocean basins, and it runs over, covering the borders of the continents. If a medal be partly sunk under water the image and superscription standing above water would repre sent a continent with adjacent islands and the sunken part just submerged would represent the continental shelf. The litho sphere's surface may be considered to consist of three parts, namely, the continent heights 21%, the deep ocean 641% and a transitional area separating them. This transitional area of slight gradient is almost bisected by the present coast-line, for nearly one-half of it (io,000,000 sq.m.) lies under water less than 'co fathoms deep, and the remainder is under 600ft. in elevation. The former is called the continental shelf, and represents the area which would be added to the continents if the land rose 600 feet. This shelf varies in width; surrounding it, leading to the great depths, is Wagner's continental slope. Around Africa— except for isolated patches—and off the western coasts of America the shelf scarcely exists. It is wide under the British Isles and northern France, and extends as a continuous platform under the whole of the North sea except off south-west Norway. It unites Australia to New Guinea on the north and to Tasmania on the south, connects the Malay Archipelago along the broad shelf east of China with Japan and unites north-western America with Asia. It curves southwards outside Newfoundland and northwards holds Hudson Bay in the centre of a shallow dish. It adds considerable areas to the real oceanic boundaries of eastern United States, Florida, the Gulf States, eastern Central America and equatorial Brazil, while southwards the Falklands rise from its eastern border. In many places it is a plain of marine de nudation, where the waves have battered down the cliffs and dragged the eroded material under the present sea level. If there were no compensating action in the differential movement of land and sea in the transitional area the whole of the land would be gradually planed down to a submarine platform, and all the globe would be covered with water. There are, however, periodi cal movements of this transitional area by which fresh areas of land are raised above sea-level, while the sea sinks more deeply into the great ocean basins, and the enlarged continents offer a new strip to the unceasing action of the waves.