(Transition } | | to shelters.) } RIVER- | | } DRIFT | | 2. CHELLEAN. } AND " 100,000. | | } TERRACE | | 1. PRE-CHELLEAN (MESVINIAN.) } PERIOD. | | } | | _EOLITHIC._ | +----------------------------------------------------------------------+ GEOLOGIC HISTORY OF MAN Man emerges from the vast geologic history of the earth in the period known as the Pleistocene, or Glacial, and Postglacial, the 'Diluvium' of the older geologists. The men of the Old Stone Age in western Europe are now known through the latter half of Glacial times to the very end of Postglacial times, when the Old Stone Age, with its wonderful environment of mammalian and human life, comes to a gradual close, and the New Stone Age begins with the climate and natural beauties of the forests, meadows, and Alps of Europe as they were before the destroying hand of economic civilization fell upon them. [Illustration: PL. II. "Throughout this long epoch western Europe is to be viewed as a peninsula, surrounded on all sides by the sea and stretching westward from the great land mass of eastern Europe and of Asia, which was the chief theatre of evolution both of animal and human life." 1-8. Discovery sites of the type specimens of human and prehuman races.] It is our difficult but fascinating task to project in our imagination the extraordinary series of prehistoric natural events which were witnessed by the successive races of Palæolithic men in Europe; such a combination and sequence never occurred before in the world's history and will never occur again. They centred around three distinct and yet closely related groups of causes. First, the formation of the two great ice-fields centring over the Scandinavian peninsula and over the Alps; second, the arrival or assemblage in western Europe of mammals from five entirely different life-zones or natural habitats; third, the arrival in Europe of seven or eight successive races of men by migration, chiefly from the great Eurasiatic continent of the East. Throughout this long epoch western Europe is to be viewed as a peninsula, surrounded on all sides by the sea and stretching westward from the great land mass of eastern Europe and of Asia, which was the chief theatre of evolution both of animal and human life. It was the 'far west' of all migrations of animals and men. Nor may we disregard the vast African land mass, the northern coasts of which afforded a great southern migration route from Asia, and may have supplied Europe with certain of its human races such as the 'Grimaldi.'