James Oeikie—^ On Seasonal Migrations. 53 



while, in the opposite season, all the isooheimal lines are swept 

 boldly north and north-east. 



Were the Mediterranean to be converted into two land-locked 

 seas, the isotheral lines in that area would then be less disturbed, 

 and Would preserve the general south-west and north-east trend 

 which they follow in central Europe., The summers in Italy, 

 Turkey, and Greece would thus be somewhat hotter and drier, but the 

 general summer temperature of Europe would remain unaffected. 

 The winds flowing from the south would no doubt be warmer, but 

 they would also carry less moisture. When they reached the Alps, 

 they would part with their warmth and moisture, just as they do 

 now; but since they would bring more of the one and less of the 

 other than at present, the snow-fields and glaciers on the south side 

 of the Alps would tend to shrink back. Again, the isothermal chart 

 shows that the supposed increase of land would not produce any 

 appreciable climatal effect beyond a short distance into Spain and 

 Prance, while not a trace of its influence would reach England. 

 The Continent, laved along its entire western borders by a wide 

 ocean, would be cooled over an immense area by the winds blowing 

 from west and south-west ; such is the case now/ and it must have 

 been equally so in late Pleistocene times. Nor can we forget that 

 the presence of great snow-fields and glaciers in every mountain 

 district would tend still more to keep down the summer temperature. 

 Thus, even had the warmth derived from the Mediterranean area 

 been ten times greater than we can conceive it to have been, its effect 

 would, nevertheless, be counterbalanced, and far more than counter- 

 balanced, by the influence of the Atlantic and the presence of the 

 glaciers and snow-fields. Mr. Dawkins, however, thinks, that " the 

 inference that the summer temperature would be lower than at 

 present in Britain, because there were glacier-areas in the north and 

 in the higher districts in Central Europe, is inconclusive, since the 

 mere existence of a glacier tells us nothing of the summer heat 

 of the surrounding regions. Could we predicate, for instance, the 

 temperature of the Subhimalayas from the contemplation of the 

 glaciers of the central ridge? or the summer heat of Lombardy 

 or of Provence from the glaciers of the Alps? " I confess I do not 

 see the force of these remarks. Britain is not in the latitude of 

 northern India, neither is it in that of Lombardy ; while, in comparison 

 with the Alps and the Himalayas, our mountains are mere monticules. 

 We are not discussing the climate of some hypothetical land in the 

 planet Mars, but are treating of that of a well-defined region, the 

 geographical and physical conditions of which during late Pleistocene 

 times have been definitely enough determined. The causes that 

 render the summers of Europe much less excessive than those of 

 Asia and North America were assuredly in existence during the 

 period referred to. We are perfectly justified, therefore, in holding 

 that with snow-fields and glaciers in our area it is absolutely 

 impossible that our summers could have been so warm as they are 



' See Professor Coffin's elaborate memoir on the " "Winds of the Northern Hemi- 

 sphere," Smithsonian Contributions, 1853. 



