346 CLIMATIC CONDITIONS OF THE GLACIAL EPOCH. 



For this purpose we naturally and properly turn first to the largest land 

 mass of the globe, Asia, because it seems unreasonable to start ■with any 

 other assumption than that the effects of a geological event or period impor- 

 tant and general enough to be called an epoch would necessarily exhibit 

 themselves in a manner more or less strikina; on that continent which con- 

 tains compacted into one mass more than a third of the land area of the 

 globe. On examining all the facts accessible up to the present time, we do 

 not find that the Asiatic Continent presents us with evidence of a satisfac- 

 tory character that so much of its surface has ever been covered with ice 

 as to render necessary the assumption of a " Glacial epoch." This, how- 

 ever, is a statement of considerable importance, since, as all must admit, 

 an " epoch " in geology, the conditions of which did not affect a whole hemi- 

 sphere — the Southern, namely, as will be shown farther on — nor the largest 

 land mass of the globe, would be something very extraordinary. It will 

 therefore be desirable that we should give a resume, at least, of the evidence 

 which, as the writer believes, justifies the assertion that there has never been 

 an extension of the glaciers, or of the area of perpetual snow, over any 

 portion of the Asiatic Continent, sufficiently great to make it necessary to 

 assume the existence of seriously altered topographical conditions, or of 

 other climatic changes than those already shown to have taken place. 



Here, however, we must once more call attention to the necessity of 

 keeping in mind the fact which seems to have been clearly established in 

 the preceding section, that a moderate amount of increase or diminution in 

 the length of the glaciers of any particular region has no such significance 

 as would make it necessary to assume that the climatic or other conditions 

 had undergone some special and important change in order that such a 

 result might be brought about. If, however, the theory sought to be estab- 

 lished in a former chapter of this work is correct, and it be admitted that a 

 desiccation of the earth is gradually taking place, we may expect to find the 

 glaciers diminishing as well as the lakes and rivers, as has already been sug- 

 gested when discussing the changes known to have taken place within the 

 historical period in the Swiss and other glaciers. 



In this connection another consideration presents itself, as bearing on 

 the question why we could not reasonably expect that the glaciers of all 

 regions should show in the same way or to an equal amount the effect of the 

 desiccation believed to be taking place. This desiccation is accompanied, 

 and in part caused, by a diminution of the temperature, Avhich also must 



