MOUNTAIN VEGETATION. 449 



magnitude it is not easy to place a limit upon. Wind 

 moving at the rate of 100 or 120 miles an hour will 

 thu s (in the form of a hurricane) be capable of levelling 

 most structures erected by human hands which lie 

 directly in its path. 



We propose to close this section with a brief review 

 of the phenomena exhibited in great mountain regions 

 among the representatives of the vegetable kingdom, 

 which are not a little remarkable. The slopes of lofty 

 mountain ranges in fact constitute everywhere quite a 

 little world of their own, and at different elevations 

 their sides are marked by special belts of vegetation, 

 from the level of the plain to the limits of eternal snow. 



It is a well ascertained fact that the range of plant 

 life is everywhere dependent upon temperature, com- 

 bined with the quantity of moisture contained in the 

 atmosphere, and the amount of the rainfall. The 

 geographical distribution of plants therefore depends 

 almost altogether upon climate, the nature of the 

 soil being with the great majority generally a 

 matter of comparatively minor consideration. It is true 

 that certain sorts of plants are much more fastidious 

 in their nature than others, and will only grow under 

 certain conditions, as to soil, aspect, etc. These plants 

 however constitute the minority, and the main principle 

 which governs the general aspect of the vegetation of 

 a country is climate. Now upon the slopes of a great 

 mountain every sort of climate prevails, according to 

 altitude, varying from that of the plain out of which 

 it takes its rise to that of the Arctic Zone. So again 

 in many parts of the world, one side of a mountain 

 range will have abundant moisture and copious rainfall, 

 while on the other, in the same parallel of latitude, there 



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