27 



portion of the range will be overstocked while another j)ortion will be 

 nnderi^razed. In the one case the grasses are eaten down and trampled 

 for a few miles back from the water so that it may reqnire several 

 good seasons to undo the injury done in one bad year. In addition, 

 the forage on the large area back from the water is entirely lost through 

 not being grazed. The cost of constructing dams or providing wind- 

 mills will often be but a small percentage of the loss incurred when no 

 water is provided. It has been often observed that the period of How 

 of the rivers in countries wliich have been overgrazed is very much less 

 than it was formerly. This is because the tramjding of the herds has 

 compacted the soil, and also because the waters are not retarded from 

 running off the surface as they would be when the land is covered with 

 a thick coating of grasses. Hence the drainage of the surplus water 

 takes place in a very much shorter time. There are many streams and 

 springs which in former years afforded a continuous supply throughout 

 the dry season, which now only run during or immediately succeeding 

 periods of abundant rainfall. Thus less dei)endence is to be placed 

 upon the streams as a source of stock water. New artificial sources of 

 supply must be provided. 



GRAZING REGIONS IN TEXAS AND NBV7 MEXICO. 



Texas may be divided into seven or eight well-defined agricultural 

 jtrovinces, each differing from the others in the general character of the 

 soil and amount of rainlall. These differences of soil are mainly due to 

 difference in geological formation, while the causes of the climatic 

 variation are the natural phenomena which govern continental condi- 

 tions, such as altitude, proximity to the Gulf, and presence or absence 

 of vegetation. The areas or belts where soils and natural conditions 

 are alike, or have only casual differences, are usually marked by the 

 growth of certain plants, which form a characteristic, though not always 

 the most prominent feature, in the grass flora. The region under dis- 

 cussion may well be divided along these lines and treated by areas.* 

 These are: 



The Coastal Prairies, bounded by a line drawn parallel with the coast 

 about 70 miles back from the Gulf. 



The Cactus Plains, which include all of the region between the 

 Colorado and Rio Grande from the border of the coastal prairies to the 

 " rim " of hills that breaks to the northward from San Antonio, just 

 below the thirtieth parallel of latitude. 



The Middle Plain, a low table-land, rather mountainous, extending 

 from the southern "rim" to the Concho, and from the Colorado to the 

 Pecos. This is the Edwards Plain of the geologists. 



The Granite Region, occupying a very limited area in the center of 

 the State between the central plain and the red prairies. 



* From data supplied by Prof. Robert T. Hill, of the United States Geological 

 Survey. 



