242 THE SMALL GRAINS 



of climate also, the Great Plains is usually considered to 

 extend eastward only to about the 96th meridian. 



253. Depth of soil. The depth of Great Plains soil 

 varies from 6 inches to several feet. It is unusually deep 

 and black in the valley of the Red River of the North. 

 At the different substations of the Great Plains, under 

 federal and state control, the soil of real use to the crop 

 varies in depth from 2 to 8 feet, but sometimes terminates 

 in a subsoil practically the same. 



In the southwestern plains are large areas of " red 

 beds," with which are often associated impregnations, at 

 considerable depth, of gypsum and rock salt, similar to the 

 deposits above mentioned as occurring in southeast 

 Russia. 



254. The Argentina Pampas. In Argentina exists a 

 formation known as the Pampas, similar in many ways 

 to the Great Plains and the Chernozem. The Pampas 

 proper appears to be only a part of a much larger forma- 

 tion including the Chaco, and extending over 700 miles in 

 length and 400 miles in breadth, northward and south- 

 westward from the Rio de la Plata estuary. The climatic 

 and soil features, though as yet little studied, are such as 

 favor a large cereal production, which fact is confirmed 

 by the rapid strides made by Argentina in cereal exports 

 in recent years. However, the greater rainfall over a 

 large part of the area, and possibly other conditions, have 

 resulted in a less protein content in Argentina wheats than 

 in those of the Russian and North American Plains. 



South of the Rio Negro there is a second steppe, the 

 plains of Patagonia, in a portion of which, at least, condi- 

 tions are more ideal for wheat production than in the 

 north, but the region is yet little developed. It is higher 

 and drier, and the winters are colder. In all the plains 



