Early Acheulean. Broad oval 'coups de poing' much more symmetrical than the Chellean but still rather heavy. Small types.
Late Chellean. Long pointed 'coups de poing,' in most cases flaked on both sides, with little of the crust of the nodule adhering and the edges still unsymmetrical. First appearance of the oval 'coups de poing.'
Early Chellean. First appearance of 'coups de poing' of almond shape. Small implements, including scrapers, planes, and borers. All implements unsymmetrical and with uneven edges.
Pre-Chellean. Probable industry of the Piltdown and of the (Pre-Neanderthaloid) Heidelberg races. Use of chance and accidental forms. Forms partly accidental; retouch limited to the few strokes necessary to give a point or edge to the tool, or to allow a firm grasp (protective retouch). Prototypes of 'coup de poing' formed of flint nodules with crust only partially removed.
If we suppose that the Pre-Chellean flint workers arrived in Europe not earlier than Third Interglacial times, we can explain all the gradations in the evolution of their implements in connection with the changes of climate and of animal life which the geologic and fossil deposits reveal, especially in the valleys of the Somme and of the Thames.
If, on the other hand, the Pre-Chellean is dated in Second Interglacial times,[U] it carries this culture back another hundred thousand years and involves our prehistory in great difficulties. First, there is no proof whatever that the Pre-Chellean and Chellean flint workers lived during the period of the formation of the 'high river terraces' of the third glaciation, for no Palæolithic flints have ever been found buried in the sands or gravels of the 'high terraces.' The occurrence of archaic flints on the 'high terraces' of the Somme and of the Seine is in superficial gravel beds which were deposited long after these 'terraces' had been cut by river action; this is best seen in the Somme, where archaic flints occur alike in the gravels deposited upon the 'low,' 'middle,' and 'high terraces.' Second, there is no proof that the Pre-Chellean and Chellean flint workers passed through the cold climatic period of the third glaciation; nowhere in Europe have any records been found of their camps or stations in association with the cold fauna or flora of Third Glacial times. Third, the geographical evidence is equally at variance with the theory that the Pre-Chellean flint workers entered Europe during the Second Interglacial Stage, for we know positively that in many of the great river-valleys of Europe, especially those surrounding the Alps, the rivers were at much higher levels than at present and that they were transporting the materials out of which the 'high terraces' were being formed or cutting these 'terraces' down by erosion.
In other words, the geography of Europe in First and Second Interglacial times was very different from what it is at present; most of the river-valleys were broader and less deep; some of them had been eroded to a point below their present levels and had begun to silt up in alluvial deposits. In Third Interglacial times the river geography of Europe was substantially as it is to-day, although the coast-lines were still very different.
When Pre-Chellean man appeared, we shall see that the river-valleys of the Somme and Marne, in northern France, as well as of the Thames, in southeastern England, were closely similar to what they are at present in respect to their water-levels; in other words, the inland geography of Europe in the north in Chellean times and in central and southern France in the immediately succeeding Acheulean times was very much like it is at present. The superficial characters of the valleys were different; the streams in Chellean times flowed through gravels and sands, partaking of a glacial aspect; one or more of the 'river terraces' composed of sands and gravels were still sharply defined, for the soft covering of 'loam' and alluvial soil from the surrounding uplands and hills had not yet washed down to soften the outlines of the 'terraces.' Neither were the 'terraces' covered with the newer deposits of 'loess.'
