116 NORTH AMERICA 



climatic aridity is enhanced by the porous nature of the 

 lava which covers most of the surface of the peninsula : 

 but a material change intervenes towards the point 

 of lower California, due to a combination of granite soil 

 and irregular monsoon rains. In favourable places, 

 wellnigh all tropical fruits, mango, papaw, banana, &c., 

 can be successfully grown ; and on the longitudinal 

 ridges of the peninsula are scattered coniferous woods. 

 This region is practically uninhabited. 



The western coastal shelf of the mainland of Mexico 

 becomes increasingly fertile towards the south. Numerous 

 mountain torrents water the naturally generous soil; 

 but while the mountains in the rear receive the benefit 

 of the monsoons, the plains are too low to condense the 

 moisture, and they remain half arid outside the narrow 

 margins of the rivers. It is a land of ragged, dry 

 pastures dotted with cacti and candelabra-cerei, and 

 of prickly jungles or chaparral mostly composed of 

 acacias. The sweltering marshes and lagoons which the 

 rivers create along the Pacific coast support extensive 

 palm-forests. At present thinly peopled, the western 

 lowland of Mexico, if due advantage be taken of the 

 facilities of irrigation, is favourably situated for semi- 

 tropical and tropical agriculture. 



Ascending the Sierra Madre, one leaves behind the 

 well-defined belts of vegetation which correspond to an 

 increase of rainfall and mists, and to a lowering of 

 temperature. The valleys become abundantly wooded 

 and display a luxuriance only second to that of the 

 tropical rain-forests, while the ridges remain semi-arid. 

 Further up, the landscape turns more and more to a 

 mountain park, extremely diversified, where pastures 

 alternate with extensive forests of pines, firs, and ever- 

 green oaks. By reason of the variety of climates from 



