Men of the Old Stone Age: Their Environment, Life and Art

by Henry Fairfield Osborn

Fig. 59. Section of the ancient river terraces on the south bank of the River Somme at St. Acheul-Amiens, showing stations on the low, middle, and high terraces where flints were worked from the very beginning to the very end of the Old Stone Age. After Commont, 1908, 1909—modified and redrawn. The section shown runs northwest and southeast, in a gentle slope nearly 1½ miles in length, from the summit, 70 meters (about 230 feet) above sea-level, down to the river 47.3 meters (155 feet) below. Since Rigollot's excavations in 1851 sixteen flint-working stations have been discovered here, chiefly through building operations, most of them being on the middle and high terraces. This gives some idea of the vast extent of these ancient encampments, which cover the entire period of the Old Stone Age—perhaps 125,000 years.

Prehistory of St. Acheul

NEOLITHIC.
Campignian, recent earth and loam.

UPPER PALÆOLITHIC.
Solutrean.
Upper Aurignacian, loam.
Middle Aurignacian, 'newer loess' and gravel.

LOWER PALÆOLITHIC.
Late Mousterian, gravel and 'newer loess.'
Early Mousterian, base of 'newer loess' (l'ergeron).
Middle Acheulean, 'older loess' and drift.
Early Acheulean, gravels below 'older loess' (E. antiquus).
Late Chellean, fluviatile sands and mollusk fauna.
Early Chellean, first coups de poing; old 'white sands' (E. antiquus).
Pre-Chellean, prototypes of coup de poing; old 'lower gravels' (E. antiquus).

The history of the climatic changes in the ancient valley of the Somme is most clearly written in these successive deposits, 15 feet in thickness, above the 'lower gravels' at St. Acheul. Along with the Pre-Chellean and Chellean flints in the 'old gravels' and 'white sands' we find records of the moist warm temperate climate which then prevailed in northern France and which undoubtedly was most favorable to the hippopotami, rhinoceroses, and elephants of those times. The river mollusks found with the late Chellean flints are another indication of the temperate forest climate which continued through early Acheulean times.

In the middle Acheulean are found the earliest deposits of 'older loess' which indicate a climate still temperate but arid, belonging to the middle of the Third Interglacial Stage. In Mousterian times we find heavy deposits of gravels corresponding to the moist cold climate of the Fourth Glacial Stage, followed in middle Aurignacian times by fresh layers of 'newer loess,' indicating the return of a dry climate. Finally, the layers of loam which were washed down over the sides of the valley, and in which the remains of Solutrean and Aurignacian camps are found, indicate the renewal of moist and probably forested conditions.

Thus, two dry loess periods are indicated in this valley, the first or 'older loess' belonging to Third Interglacial times, and the second or 'newer loess' to Postglacial times; and we clearly perceive that in the culture layers here there is no evidence whatever of more than one glacial stage preceded by a dry climatic period and deposits of loess. If the Pre-Chellean flint workers had arrived in this river-valley as early as Second Interglacial times, we should find proofs of three periods of arid climate and loess deposition and of two glaciations.

Beginning with middle Acheulean times the flints are found in deposits of gravels, loams, brick-earths, and 'older loess,' which all belong to a succeeding geologic stage and are of more recent date than the lower gravels and sands on the terraces which they overlap and conceal. Deposits of this kind have also been drifted down from the highest levels toward the bottom of the valley, and Commont distinguishes three different depositions or layers of 'loess loam,' the lowest or oldest of which contain Acheulean flints, while the middle loams contain Mousterian implements.