CLIMATE AND VEGETATION. 50 



rocky hills are partly covered by tliickets, and on 

 the banks of the larger streams, especially to the 

 north of Las Minas, willow-trees are not uncom- 

 mon. Near the Arroyo Tapes I heard of a v/ood 

 of palms ; and one of these trees, of considerable 

 size, I saw near the Pan de Azucar, in lat. 35°. 

 These, and the trees planted by the Spaniards, offer 

 the only exceptions to the general scarcity of wood. 

 Among the introduced kinds may be enumerated 

 poplars, olives, peach, and other fruit trees : the 

 peaches succeed so well, that they aftbrd the main 

 suj)ply of firewood to the city of Buenos Ayres. 

 Extremely level countries, such as the Pampas, 

 seldom appear favourable to the growth of trees. 

 This may possibly be attributed either to the forco 

 of the winds, or the kind of drainage. In the na- 

 ture of the land, however, around Maldonado, no 

 such reason is apparent ; the rocky mountains af- 

 ford protected situations, enjoying various kinds of 

 soil ♦ streamlets of water are common at the bot- 

 toms of nearly every valley ; and the clayey nature 

 of the earth seems adapted to retain moisture. It 

 has been inferred with much probability, that the 

 presence of woodland is generally determined* by 

 the annual amount of moisture ; yet in this prov- 

 ince abundant and heavy rain falls during the win- 

 ter ; and the summer, though dry, is not so in any 

 excessive degree.t We see nearly the whole of 

 Australia 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 



* Maclaren, art. " America," Encyclop. Britann. 



+ Azara says, " Je crois que la quantite annuelle des pluies est, 

 dans toutes ces contrees, plus considerable qu'en Espagne." — Vol. 

 i., p. 30. 



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