conditions.

There were four periods of advance before the final retreat of the ice, not counting minor oscillations.18 These are known as the Gunz, Mindel, Riss, and Wurm Glacial Epochs. Alternating with these were the interglacial epochs of ice retreat—the Gunz-Mindel, Mindel-Riss, and Riss-Wurm; while the final retreat is usually termed post-glacial. During the first and second interglacial epochs the climate appears to have been warmer than at present. But at times dryness may have contributed to the retreat of the ice even more than warmth, and then the climate would have been continental, harsh, and extreme.

Even during epochs of glacial advance conditions in France and in the German zone must have been better than we should expect. Some kind of grazing or browsing pasturage must have been rich and abundant to support large animals like the reindeer or even the woolly mammoths characteristic of the second and third glacial epochs, which furnished abundant food for prehistoric hunters. Farther south the glacial epochs may well have been times of heavy rainfall, transforming the Sahara desert and the dryer steppes and plateaus of Asia into veritable gardens.

The retreating ice left behind it a land covered with rocks, clays, gravels, and sands brought by the glaciers and their streams. Here and there basins had been gouged out where lakes or ponds long remained—as in Maine and Minnesota to-day—to be later drained, or, if shallow, to be overgrown with sphagnum and changed into great bogs. Scattered thickets of shrubs and stunted hardy trees, poplars, willows, and others occurred. In sheltered and well-drained valleys and mountainsides the trees grew larger and even forests began to appear. This tundra landscape still characterizes wide areas of northern Canada and Siberia.19

The tundra was followed by steppe conditions, where elevation of land to the north and northwest had cut off the tempering oceanic winds. The climate was harsh, dry, continental, with cold winters and hot summers. The winds carried great storms of dust and piled it up in drifts in valleys and on suitably situated mountainsides in the form of loess, so important to the future agricultural development of Europe, though its most massive accumulation is seen in China, which received and held the driftings from the great elevated plains of central Asia. As the climate became moister, if the temperature did not fall too low, steppe finally gave way to the meadow and forest of modern Europe. Tundra, steppe, and forest had each its special types of animal as well as plant life. The characteristic tundra animal is the reindeer, though musk-ox, woolly mammoth, and others were wide-spread at this time. The peculiar steppe animal is the horse. The characteristic forest and meadow animals are the deer and their allies; the wolf and bear; the wild boar and cattle seem to be at home in forest and glade and along the streams.

In France, where there was far less glaciation, the succession of tundra, steppe, and forest is less apparent. Here we find a mingling of varied forms which have come in from very different regions, driven from their original homes by change of climate or drawn by favorable conditions.

The first unmistakable relic of man in Europe is a human lower jaw found in the Mauer sands near Heidelberg, some seventy-nine feet below the surface of the bluff.20 It seems to belong to the second or Mindel-Riss interglacial epoch, and its age is estimated by Osborn at about 250,000 years. Remains characteristic of the oldest Paleolithic epochs occur between thirty and forty-five feet below the surface. If we are to find an archæological name for this epoch, there seems to be no better one than Eolithic, the dawn of the Stone Age, when European man had hardly more than begun to chip a stone implement, although we must recognize the unreadiness of many or most archæologists to find a place for such rude products.21

The third interglacial period (Riss-Wurm) and the fourth period of advance (Wurm) cover what is known as Lower Paleolithic time, which is the earlier four-fifths or more of the Old Stone Age or Paleolithic period, extending approximately from 125,000 B. C., to 25,000 B. C. During the greater part of this period Europe was occupied by the Neanderthaloid people. Neanderthal man had a very large head with heavy, overhanging eyebrows meeting above the nose, and a markedly retreating forehead. The face was high and the large nasal opening indicates a broad, flat nose. The lower jaw was heavy and the chin retreating. The trunk was short, thick, and robust, the shoulders broad; the limbs short and heavy, the arms and lower legs relatively short, and the hands very large. Although the much-discussed Piltdown skull may quite probably be regarded as belonging to the earliest part of this period, the finer form of cranium seems to testify to a higher race of better mental development than the Neanderthaloids, huddling in their caves and shelters. It may easily represent a far more progressive ancestral race, of which they are somewhat degenerate descendants, though Osborn dissents from this view.22

Their remains are found in caves and rock-shelters all over Europe. Here we find their hearths; the bones of the animals which they had hunted for their food; their almond-shaped flint axes, “hand-stones” (Coups-de-Poing), the scrapers for dressing skins and shaving wooden tools, and a variety of other forms. Here they buried their dead. During the third warm interglacial epoch they lived in the open, as at the station of Chelles, which has given its name to the earliest Paleolithic epoch.23 Their origin and route of migration is quite uncertain, but it seems probable that they entered Europe from the southern shore of the Mediterranean.

The post-glacial period is characterized by the final retreat of the ice. The change of climate was not steady but marked by a series of oscillations, repeating on a much smaller scale the glacial and interglacial epochs of the long past. The climatic change is accompanied by the appearance of tundra and steppe, followed by meadows and the forest conditions of modern times. Game was abundant and general conditions severe but healthy and fairly favorable.

A new race has appeared on the scene which replaced the Neanderthal folk, and had practically none of their primitive or degenerate, ape-like characteristics.24 The Cro-Magnon people have