ELEVATED PLATEAUS. 363 



structural system throughout the whole. The same chapter 

 singularly monotonous aspect pervades the vast area "^^^ 

 extending fi-om Westphalia to the banks of the Obi Great plains 

 and the Lena. The great plains are evidently the pri- 

 mitive structures upheaved by some prolonged but 

 uniform action extending over an extremely wide area. 

 Upon this the chains of mountains have been superin- 

 duced by subsequent upheavals, acting more irregularly 

 over a more limited surface. The direction of south- 

 west by north-east is, however, traceable alike in the 

 principal axes of these vast elevated plateaus, and in the 

 chains of mountains of later formation ; so that a con- 

 nexion appears thus traceable in the sources of these Sources of 

 successive upheavals, though productive of results so 

 very different. The influence of the geological features 

 resulting from these combined actions is very remarkable. 

 The effect of these elevated plateaus, with their systems 

 of mountain chains, is specially noticeable in relation to 

 climate, and consequently to the distribution of the 

 vegetable kingdom, to the nature of the animals located 

 on their surface, and no less so to the physical and men- 

 tal peculiarities of the large portion of the human race 

 settled within these districts. 



Leaving this extremely interesting branch of the In- Relations of 

 quiry which relates to the distribution of life in all its nio'untain 

 various forms as exhibited in the animal and vegetable systems. 

 kingdoms and in man himself, the observant traveller 

 next proceeds to examine the relative connections of the 

 area of the plains, and the area of the chains of moun- 

 tains, and deduces from thence important conclusions in 

 relation to the centre of gravity of that portion of our 

 planet whicli is elevated above the present level of the 

 sea. This subject had already excited much interest in 

 the minds of various distinguished European scientific 

 men, well qualified to investigate such phenomena, but 

 possessed of very limited opportunities of comparison 

 and observant study, when contrasted with those which 

 Humboldt has commanded during his sojourn on the 



