120 PATAGONIA AND SHEEP-REARING 



coast, and merely relax a little in the winter. The 

 mean temperature on the Atlantic coast falls nearly 

 one degree for each degree of latitude (14.6 at 

 San Antonio, below 41 S. lat. ; 8.5 at Santa Cruz, 

 below 50 S. lat. ; and 5.3 at Ushuaia, below 55 S. 

 lat.). The summer temperature falls even more steeply, 

 but the difference is less notable in winter (21.4 at 

 San Antonio, 14 at Santa Cruz, and 9.2 at Ushuaia). 

 The low summer temperature does not allow cereals 

 to ripen south of the Chubut. In the sub- Andean 

 valleys the summer is comparatively warm (16 in 

 January at Diez y seis de Octubre at a height of 1,800 

 feet), but there is severe frost, especially at the beginning 

 of the winter, and no month of the year is quite free 

 from it. 



Rain is plentiful in the Cordillera, and on its western 

 border : 800 millimetres at Junin, nearly two metres 

 at San Martin (which the wet westerly winds reach 

 by the gap of Lake Lacar), and nearly a metre at 

 Bariloche, on Lake Nahuel Huapi. It diminishes 

 rapidly, however, as soon as one leaves the moun- 

 tainous region and goes further east over the table- 

 land. The whole tableland has a rainfall of less than 

 200 millimetres (Las Lajas 180, Limay 150, San Antonio 

 180, Santa Cruz 135). It is only south of the Rio de 

 Santa Cruz that the rainfall rises once more (Gallegos 

 400 millimetres, Ushuaia 500 millimetres). Hence 

 Patagonia as a whole is, with the exception of a narrow 

 belt at the foot of the Andes, a semi-arid region with 

 a sub-desert climate. In the Patagonian Andes the 

 rain falls, as on the coast of Chile, mainly in winter. 

 Between Mendoza, which has the summer-rain feature 

 of central and tropical Argentina, and Chosmalal, 

 in the Neuquen Andes, the contrast is absolute. The 

 summer months there (January and February) are 

 dry, and the rain is confined to the winter months, 

 from May to August. It is the same further south, 

 at Bariloche and at Diez y seis de Octubre. On the 



