Vol. 57.] THE CLIMATE OF THE PLEISTOCE]!fE EPOCH. 455 



sion than that of the present da)-. Prince Kropotkin, quoted by 

 Prof. James Geikie/ believes that 



' the whole of the upper plateau of Aaia and its border-ridges were under a 

 mighty ice-cap.' ^ 



Even if such a view may be regarded as extreme, it seems probable 

 that the summer climate of Central Asia may have been sufficiently 

 cold to permit of the existence of permanent snowfields on a more 

 extensive scale than those of the present day. 



VII. The Meteorological CoNoiTioisrs during the Maximttm 

 Glaciation of Ecrope and of the British Isles. 



"While, hovrever, the meteorological conditions of Northern Europe 

 in winter during the maximum glaciation of America may have 

 more or less closely corresponded with those of the present era, 

 the state of things in the North Atlantic basin must have been 

 widely different when the Scandinavian ice invaded the North 

 Sea, leaving its traces far to the south in Holland ^ and elsewhere 

 in Central Europe ; when the glaciers of Switzerland and the 

 Pyrenees extended greatly beyond their present limits ; and 

 especially when independent centres of ice-dispersion existed in the 

 British Isles. 



It is difficult to understand why, when such conditions as those 

 described as possibly obtaining during the glaciation of North 

 America had once established themselves, they did not become 

 permanent, so long as the wave of cold air (to which the glaciation 

 of the Northern Hemisphere was due) continued. If, however, we 

 accept the view that Europe and the British Isles were probably 

 not glaciated contemporaneously with the maximum extension of 

 the ice in North America, we are justified in endeavouring to trace 

 out the meteorological conditions under which ice-sheets . could 

 reasonably have existed in the former, even if it is difficult to explain 

 how it came to pass that they extended southward from the 

 Arctic Circle, at one time over the New, and at another over the 

 Old \¥orld. 



It was shown by James CroU that the direction of oceanic currents 

 corresponds generally with the direction of the prevalent winds,^ 

 and that the former are largely due to the latter. He further 

 pointed out that an alteration in the direction of the marine currents 

 would affect climate." His view was that, during the Glacial Period, 



1 ' The Great Ice Age ' 3rd ed. (1894) p. 697. 



'^ [The recent observations of Prof. Gr. F. Wright, Quart. Journ. Geol. See. 

 Tol. Ivii (1901) pp. 244-50, do not support this view. I have consequently 

 omitted from two of my diagrams a small anticyclone which I had shown aa 

 formerly existing during the summer in Central Asia.] 



^ Scandinavian boulders are exceedingly common in some morainic deposits 

 near Utrecht; see Quart. Journ. Geol. Soc. vol. lii (1893) p. '774. 



^ 'CHmate & Time' 1875, pi. 1, facing p. 212. In the Bay of Bengal, the 

 Arabian Gulf, and the Chinese Sea, moreover, the local surface-currents vary at 

 different seasons with the changes of the wind. 



'" Oj). cit. p, 26. 



I 



