178 THE PLAIN OF THE PAMPAS 



and extreme south-west of Cordoba province) the 

 soil gets increasingly more sandy, and the climate 

 drier. A single tillage suffices to destroy the natural 

 vegetation and clear the place for lucerne. The 

 lucerne fields have been created by the breeders them- 

 selves, the sole masters of the region, without the aid 

 of the colonists. 



4. Beyond the lucerne belt, at the point where the 

 plain rises toward the Sierra de San Luis and the Sierra 

 de Cordoba, the subterranean water sinks deeper. 

 This zone at the foot of the ranges, unsuitable for lucerne, 

 yet with a soil comparatively rich in humus, has been 

 taken up by agricultural workers. The wheat area 

 extends, in the San Luis province, as far as Fraga and 

 Naschel, in the Conlara depression. The maize area 

 extends to Oncativo, in the Cordoba province, between 

 the Tercero and Secundo rivers, where the summer 

 rainfall is heavier. Thanks to the nearness of the 

 mountains, this area has a water-supply for irrigation, 

 and this sustains several small centres of good farms. 



5. The south of the Buenos Aires province and the 

 central Pampa are the wheat zone. The bed of tosca, 

 which is not far below the soil, does no harm to the 

 wheat except in years of drought. The valleys, where 

 the tosca is interrupted, and the dunes, where the soil 

 is deep, are very carefully used for lucerne fields of 

 limited extent. Wheat-growing seems now, both in 

 this and the preceding zone, to have reached its limit, 

 as the dryness makes it improbable that there will be 

 any extension westward. 



6. Lastly, the east of the Buenos Aires province, 

 the centre of which is fairly indicated by the little 

 town of Dolores, is the only part of the Pampean plain 

 which has not been reached by agricultural coloniza- 

 tion. The land lies low, and is badly drained. The 

 only change that has taken place in the vegetation is a 

 progressive improvement due to the hoofs of the cattle 

 during their long stays there. This pastoral area is 



