raised beaches near Calais and on the south coast of England.
All things considered, it looks as if pre-neolithic man had to contend with more than one glacial epoch, which means an environmental disturbance of the first magnitude. Think, for example, of a great continental ice-sheet creeping slowly but inevitably down upon New York City. What an overturning of unearned increments! What a succession of Titanic disasters at sea! But unearned increments and floating palaces were happily non-existent in past glacial times. Pre-neolithic man simply abandoned his wind-break or folded his tent of skins and carried it with him. Besides the European continental ice-sheet never reached quite so far south even as London; it never covered the spots where the Piltdown skull and the Heidelberg jaw were found. There was, to be sure, a considerable extension of the Alpine and Pyrenean glaciers, but there was always enough room for safety and the survival of those best adapted to the environment.
The wide distribution in Europe of flint-bearing chalk deposits makes it almost an ideal place for the evolution of a stone-age culture. In many parts of Europe these flint-bearing deposits also afforded man ready-made shelter in the shape of caves and overhanging rocks. They are usually in proximity to water courses, and frequently so bunched as to invite a relatively dense population: those became centers of culture.
Such favored regions as the foothills of the Cantabrian Mountains in Spain, those of the French Pyrenees, the Italian Riviera, and Dordogne go a long way toward explaining the origin and evolution of paleolithic art. The great cave group of the Vézère valley became the Paris of the antique world. Here the arts flourished to a remarkable degree, beginning with the Aurignacian epoch. and continuing through to the close of the paleolithic.
It must be remembered that these early artists were limited in their choice of materials. Pebbles, pieces of schist or slate, fallen fragments from the overhanging calcareous rock, bone, reindeer horn, ivory were all utilized; but the most notable works were executed on the walls of caverns and rock shelters. Suitable wall space was at a premium; the result is that one often finds superposed figures two, three and even four deep covering the same wall space. One of the best examples of this is the great band of frescoes, five meters long, which shows interlocking of figures as well as superposition (PI. I.). Here as in practically all polychrome frescoes there is a basis of engraving which also prepares the field for the color. This foundation of engraving is seen in the upper half of the plate. The band is readily divided into four groups or sections. To the first group belong three figures all headed
