The palæontology of man has hitherto obtained good geological information of the oldest Palæolithic culture-stratum of the Drift in only a few parts of the earth, and only in Tasmania does this oldest stratum appear to have cropped out free, and still uncovered by other culture strata, down to our own times. Otherwise it is everywhere overlaid by a second, later culture-stratum of much greater thickness, which, although opened up in almost innumerable places, is not spread over the whole earth as is the Palæolithic stratum. As opposed to the earliest Stone Age of the Drift, which we have come to know as the Palæolithic Period, this has been called the Later Stone Age or Neolithic Period. The Neolithic Period is also ignorant of the working of metals; for weapons and implements, stone is the exclusive hard material of which the blades are made. But geologically and palæontologically the two culture-strata are widely and sharply separated. As regards Europe, and a large part of the other continents, the second stratum of the culture of the human race still lies at prehistoric depth. But in other extensive parts of the earth the stratum of Neolithic culture was not covered by other culture-strata until far into the period of written history. Even a large part of Europe was still inhabited by history-less tribes of the later Stone Age at the time when the old civilised lands of Asia and of Africa, and the coasts of the Mediterranean, had everywhere--on the basis of the same Neolithic elements, with the increasing use of metals--already risen to that higher stage of civilisation which, with the historical written records of Egypt and Babylonia, forms the basis of our present chronology. When these civilised nations came into direct contact with the more remote nations of the Old World, they found them, as we have said, still, to a certain extent, at the Neolithic stage of civilisation, just as, when Europeans settled in America, the great majority of the aborigines had not yet passed the Neolithic stage, at which, indeed, the lowest primitive tribes of Central Brazil still remain. Australia, and a large part of the island world of the South Sea, had not yet risen above the Neolithic stage (Tasmania, probably, not even above the Palæolithic) when they were discovered. There the Stone Age, to a certain extent, comes down to modern times; likewise in the far north of Asia, in Greenland, in the most northern parts of America, and at the south point of the New Continent among the Fuegians.