2G0 ORIGINAL AETICLES. 



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 cm-rent from the North would 

 make a farther difference of about three or four degrees ;* 

 an alteration of the climate which would apparently be sufficient 

 to account for all the phenomena. This theory, Mr. Hopkins 

 considers as no mere h3^othesis, but as necessarily following 

 from the submergence of North America, which has been in- 

 ferred 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. Hopldns was contemplating a period anterior to that of 

 the present rivers. For if we are to adopt this solution of the diffi- 

 culty, what an immense time would be required. K, when the 

 gravels and loess of the Somme and the Seine were being deposited, 

 the Gulf Stream w'as passing up what is now the Valley of the Mis- 

 sissippi, then it follows that the formation of the loess 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 Yalley, and to the j)resence of man in 

 Western Europe. 



Thus, therefore, though the alteration of climate apparently in- 

 dicated 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 gi-eater lapse of 

 time. 



But even if the presence of the sandstone blocks, and the occa- 

 sional 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 astrono- 

 mical causes, and even to the elevation of the Andes. 



M. Boucher de Perthes has always been of this opinion. " Ce 

 " Cflquillage, cet elephant, cette hache, on la main qui la fabriqua, 

 " furent done temoins du cataclysme qui donna a notre pays sa con- 

 " figuration presente."t 



M. C. D'Orbigny, observing that the fossils found in these quater- 

 nary beds are all either of land or freshwater animals, correctly dis- 

 misses the theory of any marine action, and expresses himself as 



* Hopkins, 1. c, p. 8.5. f M*-'". Soc. d'Em. rAbbcvillc, 1861, p. 475. 



