tively from (1) valley deposits, (2) caverns and rock-shelters, and (3) human skeletal remains.
The older paleolithic horizons, the Strépyan, Chellean, and Acheulian are to be found in valley deposits beginning with the middle Quaternary. The younger paleolithic horizons are quite generally thought of as being restricted to caverns and rock-shelters. Thanks to the results of recent researches, such a view is no longer tenable. With a higher degree of precision and differentiation there is revealed the diluvial equivalents of the upper paleolithic series, Mousterian, Aurignacian, Solutréan, and Magclalenian.
As might be expected the nature of the industry in the upper diluvial series tallies with that of the cave deposits. Thus each category of finds supplements and confirms the other. The only regret of the archeologist is that the work of his predecessors could not be done over again in the light of the latest discoveries. Experimentation in any line presupposes a certain amount of waste. The coefficient of waste in archeological experimentation is unfortunately very high. The valley deposits are well-nigh inexhaustible. Much, therefore, may be expected of them. With caverns the case is different. The supply of those still untouched is limited; the list of those already wholly or in part excavated is long. Think of the Dordogne, Grimaldi, Kent's cavern, as once more virgin fields! The latter, for example, has contributed little toward a better definition of paleolithic chronology, yet judging from the published illustrations it contained practically every type of industry from the Acheulian to and including the Magdalenian.
In paleolithic studies the chief elements of control are stratigraphy, technology, and paleontology. These are all given a place in the table of relative chronology. Perhaps no better summary of the bearing of stratigraphy on the question of paleolithic man could be chosen than a composite section of nonmarine Quaternary deposits as they occur in the Paris Basin and in Belgium. I have chosen Rutot's combination of the three sections: Saint-Acheul (Somme), exploitation Helin at Spiennes, near Mons, and the Thiarmont quarry at Ecaussines, between Brussels and Mons (fig. 20). The section shows the stratigraphic relation not only of the paleolithic to the eolithic below and the neolithic above, but also, by means of a bracket, that portion of the diluvial series for which there are cavern equivalents. It should be recalled, however, that there is no direct stratigraphic relation between the cavern deposits and those of the valleys. At Saint-Acheul and Helin, industries occurred at all the horizons indicated except the Aurignacian and Solutrean. The deposits at Ecaussines corresponding to these two horizons are sterile. By going to Willendorff, in the Danube Valley, near Krems (or to the Rhine Valley), the diluvial cultural series can be completed, as has already been pointed out.
