Vol. 57.] THE CLIMATE OF THE PLEISTOCEN"E EPOCH. 461 



westward, and a state of things would liave arisen closely corre- 

 sponding with that which I suggest (fig. 21, p. 458) may have 

 obtained in winter during the maximum glaciation of Europe. 



In fig. 22, which may he compared with fig. 19 (p. 454), the 

 statistical isobaric chart for Jul}'", and with fig. 20 (p. 456), that of 

 summer during the maximum glaciation of North America, I have 

 shown the meteorological conditions of the Northern Hemisphere 

 which may have been prevalent in summer during the greatest 

 extension of the ice-sheet in Europe. If, as seems possible, the 

 Antillean region was then cyclonic ^ at that season, warm oceanic 

 winds would have been prevalent in North America over the 

 southern part of the region covered by ice during the colder epochs 

 of that continent. Interglacial conditions may thas have existed 

 in the Western, coincidently with the maximum glaciation of the 

 Eastern, Hemisphere. 



It forms no part of my theory to suppose that minor fluctuations 

 of climate in one hemisphere (like those, for example, referred to in 

 the first footnote on p. 432) were necessarily accompanied by con- 

 ditions of an opposite character in the other. Cold weather often 

 exists now on both sides of the Atlantic at the same time. It seems 

 to be under circumstances of exceptional intensity that the state of 

 things arises illustrated on p. 437 (fig. 11), when excessive cold 

 in North America coincided with abnormal warmth in Western 

 Europe. Similarly it may have been during the climax 

 of the Glacial Period only that alternate glaciation 

 of the Eastern and Western Continents took place. 



YIII. The Peevalent Stoem-Teacks of the Pleistocene Epoch. 



In figs. 17 & 19 (pp. 450 & 454) I have drawn the prevalent 

 storm-tracks of the present era during winter and summer, according 

 to Dr. Buchau.^ Originating? at the former season in the China 

 Sea, cyclonic storms travel in a north-easterly direction by Japan to 

 Kamtchatka, their course continuing eastward through Behring Sea 

 towards the American coast. Crossing the American continent 

 between 45° and 50° lat. N., the region of prevalent storms passes 

 by the Great Lakes to Newfoundland.^ Avoiding the Arctic 

 current flowing southward between Greenland and Iceland, and 

 reaching the 40th meridian or thereabouts, some storms move 

 northward, along the western edge of the Gulf Stream, towards 

 Iceland and the North Cape ; others take a more southerly course 

 across the British Isles to the Baltic, while some traverse France 

 and Southern Europe to the Black Sea. Storms occasionally pass 



1 As to this, see p. 467. 



'^ Bartholomew's ' Atlas of Meteorology ' pi. xxix. 



^ An examination of the American synoptic charts shows that some of the 

 cyclonic disturbances of the North Pacific do not cross the Rocky Mountains. 

 Others frequently arise, however, at the sume time in similar latitudes, to the 

 east of that range. 



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