arm of the sea, and the intermediate regions still bear the traces of having been an ancient sea-bed. [Illustration: Fig. 2.—THE RELIEF OF EUROPE. According to Houzeau, Berghaus, Kiepert, Olsen, and others. Scale 1 : 60,000,000.] There can be no doubt that vast changes have taken place in the configuration {9} of Europe, not only during more ancient geological periods, but also within comparatively recent times. We have already seen that a vast arm of the sea formerly separated Europe from Asia; it is equally certain that there was a time when it was joined to Anatolia by an isthmus, which has since been converted into the Bosphorus of Constantinople; Spain was joined to Africa until the waters of the Atlantic invaded the Mediterranean; Sicily was probably connected with Mauritania; and the British Islands once formed a portion of the mainland. The erosion of the sea, as well as upheavals and subsidences of land, has effected, and still effect, changes in the contours of our coasts. Numerous soundings in the seas washing Western Europe have revealed the existence of a submarine plateau, which, from a geological point of view, must be looked upon as forming an integral portion of our continent. Bounded by abyssal depths of thousands of fathoms, and submerged one hundred fathoms at most below the waters of the ocean, this pedestal of France and the British Islands must be looked upon as the foundation of an ancient continent, destroyed by the incessant action of the waves. If the shallow portions of the ocean, as well as those of the Mediterranean Sea, were to be added to Europe, its area would be increased to the extent of one-fourth, but it would lose, at the same time, that wealth in peninsulas which has secured to Europe its historical superiority over the other continents.