A similar prehistoric inversion doubtless occurs in the 'terraces' of the Thames, for materials on the 'highest terrace' (Fig. 8) contain Acheulean flints, while materials on the 'lowest terrace' belong to a much more recent age. [Illustration: FIG. 8. Section--Four terraces indicated in the valley of the Thames at Galley Hill, near London. Site of the discovery of the 'Galley Hill Man' in deposits overlying one of the high terraces. Site also of Gray's Thurrock, a deposit of Third Interglacial times containing mammals and flints of Chellean age. A typical camping station of 'river-drift man.' Drawn by Dr. C. A. Reeds.] We have no record of a single Palæolithic station found in the true original sands and gravels of the 'higher terraces' in any part of Europe; only eoliths are found on the 'high terrace' levels, as at St. Prest. The earliest palæoliths occur in the gravels on both the 'middle' and 'upper terraces' of the Somme and the Marne, proving that the gravels were deposited long subsequent to the cutting of the original terraces. Geikie,(57) moreover, is of the opinion that the valley of the Somme has remained as it is since early Pleistocene times, and that even the 'lowest terrace' here was completed at that period; this is contrary to the view of Commont, who considers that this 'lowest terrace' belongs to Third Interglacial times; a restudy of the stations along the Thames may throw light upon this very important difference of opinion. TIMES OF THE 'LOESS' STATIONS The glacial stages were generally times of relatively great humidity, of heavy rain and snow fall, of full rivers charged with gravels and sands, and with loam the finest product of the erosive action of ice upon the rocks. This loam on the barren wastes left bare by the glaciers or on the river borders and overflow basins was retransported by the winds and laid down afresh in layers of varying thickness known as 'loess.' There was no 'loess' formation either in Europe or America during the humid climate of First Interglacial times, but during the latter part of the Second Interglacial Stage, again toward the close of the Third Interglacial Stage, and finally during Postglacial times there were periods of arid climate when the 'loess' was lifted and transported by the prevailing winds over the 'terraces' and plateaus and even to great heights among the mountain valleys. As observed by Huntington(58) in his interesting book _The Pulse of Asia_, even at the present time there are districts where we find 'loess' dust filling the entire atmosphere either during the heated months of summer or during the cold months of winter. [Illustration: FIG. 9. Magdalenian loess station of Aggsbach, in Lower Austria. A quarry camping station of the open-plains type. This typical Postglacial loess deposit contains flints of early Magdalenian age. After Obermaier.]