lAP. 9 



58 TREES AND HUMIDITY. [chap 



covered by lofty trees, yet that country possesses a far 

 more arid climate. Hence we must look to some other and 

 unknown cause. 



Confining our view to South America, we should 

 certainly be tempted to believe that trees flourished only 

 under a very; humid climate ; for the limit of the 

 forest-land follows, in a most remarkable manner, that 

 of the damp winds. In the southern part of the continent, 

 where the western gales, charged with moisture from 

 the Pacific, prevail, every island on the broken west 

 coast, from lat. 38° to the extreme point of Tierra del 

 Fuego, is densely covered by impenetrable forests. On 

 the eastern side of the Cordillera, over the same extent 

 of latitude, where a blue sky and a fine climate prove that 

 the atmosphere has been deprived of its moisture by 

 passing over the mountains, the arid plains of Patagonia 

 support a most scanty vegetation. In the more northern 

 parts of the continent, within the limits of the constant south- 

 eastern trade wind, the eastern side is ornamented by 

 magnificent forests ; whilst the western coast, from lat. 

 4° S. to lat. 32° S., may be described as desert : on this 

 western coast, northward of lat. 4° S., where the trade- 

 wind loses its regularity, and heavy torrents of rain fall 

 periodically, the shores of the Pacific, so utterly desert 

 in Peru, assume near Cape Blanco the character of 

 luxuriance so celebrated at Guayaquil and Panama. 

 Hence in the southern and northern parts of the continent, 

 the forest and desert lands occupy reversed positions 

 with respect to the Cordillera, and these positions are 

 apparently determined by the direction of the prevalent 

 winds. In the middle of the continent there is a broad 

 intermediate band, including central Chile and the 

 provinces of La Plata, where the rain-bringing winds 

 have not to pass over lofty mountains, and where the 

 land is neither a desert nor covered by forests. But even 

 the rule, if confined to South America, of trees flourishing 

 only in a climate rendered humid by rain-bearing winds, 

 has a strongly marked exception in the case of the Falkland 

 Islands. These islands, situated in the same latitude 

 with Tierra del Fuego and only between two and three 

 hundred miles distant from it, having a nearly similar 

 climate, with a geological formation almost identical, 

 with favourable situations and the same kind of peaty 

 soil, yet can boast of few plants deserving even the 



