28 



The Red Prairies, extending- from the Concho to the Red River, 

 bounded on the east by the black lands and on the west by the Llano 

 Estacado, 



The Staked Plains, or Llano Estacado, a high level table-land which 

 extends into New Mexico, containing the sources of all the rivers flow- 

 ing to the eastward. 



The Pecos Valley, an elevated valley which has the same soils as the 

 red prairies, but a much smaller rainfall, so that the conditions are 

 arid. 



Before the ranges were overgrazed the grasses of the red prairies 

 were largely blue stems or sage grasses {Andropogon), often as high as 

 a horse's back. After pasturing and subsequent to the trampling and 

 hardening of the soil, the dog grasses or needle grasses {Aristlda) took 

 the whole country. After further overstocking and trampling, the 

 needle grasses were driven out and the mesquite grasses {lUlaria and 

 Bulbilis) became the most prominent species. The occurrence of any 

 one of these as the dominant or most conspicuous grass is to some 

 extent an index of the state of the land and of what stage in over- 

 stocking and deterioration has been reached. 



There is often a succession of dominant grasses in nature through 

 natural causes, but never to so marked an extent as on the cattle 

 ranges during the process of deterioration from overgrazing. Thus, the 

 grasses in any given valley are liable to change in a long series of years 

 through destruction by wood lice, prairie dogs, by fires, unusually early 

 or late frosts, or by failure on the part of the i)]ant to ri])en seed. 

 This latter contingency frequently occurs in the case of the big blue 

 stem and feather sedge, and j^robably with some other of the Andropo- 

 gon species. The curly mesquite will stand almost any amount of 

 drought, trampling, and hard usage, but is easily killed and rotted out 

 during a wet, cold winter. The drought-resistant needle grass is fre- 

 quently destroyed by wood lice over considerable areas. This usually 

 happens in the spring on burned areas after light local showers. 

 Finally, the entire seed crop may be destroyed by early autumn fires. 

 Thus it is seen that through some one of many natural causes a species 

 of grass may be all but exterminated and its place taken by others, 

 often of less value. 



On overstocked lands there is uniformly an alternation of needle grass 

 and mes(iuite at short intervals, unless the overstocking is carried too 

 far, when these perennials give way to annuals and worthless weeds. 

 The carrying capacity then depends almost absolutely on the i>roper 

 distribution of rainfall through the growing season in order to briug 

 this transient vegetation to its fullest maturity. 



THE COASTAL PRAIRIES. 



The low-lying i>rairies along the shores of the Gulf of Mexico con- 

 stitute a region of very recent geological formation; in fact, so recent 



