The second glaciation was by far the greatest both in Europe and America. In the region of the Pyrenees, which at the very much later period of the Third Interglacial Stage became a favorite country with Palæolithic man, there were glaciers of vast extent. This is realized by comparison with present conditions. The largest of the present glaciers of the Pyrenees is only 2 miles in length and terminates at a height of 7,200 feet above the sea. During the greatest glaciation the snow appears to have descended 4,265 feet below its present level. From the Pyrenees through the Gallego valley into Spain there flowed a glacier 38 miles in length, while to the north the glacier in the valley of the Garonne flowed for a distance of 45 miles to a point near Montréjeau. Even in its lower reaches this glacier was over half a mile in thickness. To the east was a glacier 38 miles in length, filling the valley of the Ariège and covering the sites of such great Palæolithic caverns as that of Niaux; it is probable that at this time the formation of this cavern began. That these glaciers were all prior to the period of the Lower Palæolithic Acheulean culture is proven by the fact that Acheulean implements are frequently met with lying on the surface of the moraines laid down by these ancient ice-floes.(33) To the north was the vast Scandinavian ice-field, which swept over Great Britain and beyond the valleys of the Rhine, Elbe, and Vistula, reaching nearly to the Carpathians. Even the lesser mountain chains were capped with glaciers, including the Atlas Mountains in northern Africa. In North America from the great centre west of Hudson Bay the ice-cap extended its drift southward into Missouri, Iowa, Kansas, and Nebraska, beyond the limits of earlier and subsequent glaciations. The materials of the chief 'high terraces' of the great river-valleys of western Europe were deposited at this time. LIFE OF THE WARM SECOND INTERGLACIAL STAGE The long warm period which followed the great glaciation is remarkable in presenting the first proofs of the presence of man in western Europe. It is the period of the Heidelberg race of man (_Homo heidelbergensis_), known only from a single jaw discovered by Schoetensack in the Mauer sands near Heidelberg, in 1907. No other proofs of the existence of man have been found in any of the deposits which took place during this vast interval of geologic time, unless we accept the theory of Penck and of Geikie that the Pre-Chellean and Chellean quarries of the River Somme belong in the Second Interglacial Stage.