cold water from the north, between the coasts of Norway and Greenland. The absence of the gulf stream would probably lower the January temperature of Western Europe 10 degrees, while the presence of a cold current from the North would make a farther difference of about three or four degrees;[1] an alteration of the climate which would apparently be sufficient to account for all the phenomena. This theory, Mr. Hopkins considers as no mere hypothesis, but as necessarily following from the submergence of North America, which has been inferred from evidence of a different nature.
In this case, of course, the periods of great cold in Europe and in America must have been successive and not synchronous; and it must also be observed, that in this suggested deflection of the Gulf Stream Mr. Hopkins was contemplating a period anterior to that of the present rivers. For if we are to adopt this solution of the difficulty, what an immense time would be required. If, when the gravels and loëss of the Somme and the Seine were being deposited, the Gulf Stream was passing up what is now the Valley of the Mississippi, then it follows that the formation of the loëss in that valley and its delta, an accumulation which Sir C. Lyell has shown to require a period of about 100,000 years, would be subsequent to the excavation of the Somme Valley, and to the presence of man in Western Europe.
Thus, therefore, though the alteration of climate apparently indicated by the zoological contents and the physical condition of the beds, might by increasing the power of the floods, add to the erosive action of the river, and thus diminish on the one hand the time required for the excavation of the valley, still the very alteration itself appears, on the other hand, to require an even greater lapse of time.
But even if the presence of the sandstone blocks, and the occasional contortions of the strata, far from being objections to Mr. Prestwich's views, seem rather to speak strongly in their favour, still the height which the gravels sometimes attain above the pre- sent water-level, is at first sight a great difficulty, and we cannot wonder therefore that these beds have generally been attributed to violent cataclysms, owing to the emergence of the land, to astronomical causes, and even to the elevation of the Andes.
M. Boucher de Perthes has always been of this opinion. "Ce coquillage, cet éléphant, cette hache, ou la main qui la fabriqua, furent donc témoins du cataclysme qui donna à notre pays sa configuration présente."[2]
M. O. D'Orbigny, observing that the fossils found in these quaternary beds are all either of land or freshwater animals, correctly dismisses the theory of any marine action, and expresses himself as
