Here, then, we have the backbone of the ancient continent which once occupied the whole of the Atlantic Ocean, and from whose washings Europe and America were constructed; the deepest parts of the ocean, 3500 fathoms deep, represent those portions which sunk first, to wit, the plains to the east and west of the central mountain range; some of the loftiest peaks of this range--the Azores, St. Paul's, Ascension, Tristan d'Acunba--are still above the ocean level; while the great body of Atlantis lies a few hundred fathoms beneath the sea. In these "connecting ridges" we see the pathway which once extended between the New World and the Old, and by means of which the plants and animals of one continent travelled to the other; and by the same avenues black men found their way, as we will show hereafter, from Africa to America, and red men from America to Africa. And, as I have shown, the same great law which gradually depressed the Atlantic continent, and raised the lands east and west of it, is still at work: the coast of Greenland, which may be regarded as the northern extremity of the Atlantic continent, is still sinking "so rapidly that ancient buildings on low rock-islands are now submerged, and the Greenlander has learned by experience never to build near the water's edge," ("North Amer. of Antiq.," p. 504.) The same subsidence is going on along the shore of South Carolina and Georgia, while the north of Europe and the Atlantic coast of South America are rising rapidly. Along the latter raised beaches, 1180 miles long and from 100 to 1300 feet high, have been traced. When these connecting ridges extended from America to Europe and Africa, they shut off the flow of the tropical waters of the ocean to the north: there was then no "Gulf Stream;" the land-locked ocean that laved the shores of Northern Europe was then intensely cold; and the result was the Glacial Period. When the barriers of Atlantis sunk sufficiently to permit the natural expansion of the heated water of the tropics to the north, the ice and snow which covered Europe gradually disappeared; the Gulf Stream flowed around Atlantis, and it still retains the circular motion first imparted to it by the presence of that island. The officers of the Challenger found the entire ridge of Atlantis covered with volcanic deposits; these are the subsided mud which, as Plato tells us, rendered the sea impassable after the destruction of the island. It does not follow that, at the time Atlantis was finally ingulfed, the ridges connecting it with America and Africa rose above the water-level; these may have gradually subsided into the sea, or have gone down in cataclysms such as are described in the Central American books. The Atlantis of Plato may have been confined to the "Dolphin Ridge" of our map. ANCIENT ISLANDS BETWEEN ATLANTIS AND THE MEDITERRANEAN, FROM DEEP-SEA SOUNDINGS