44 RANGE INVESTIGATIONS IN ARIZONA. 



Monthly totals of precipitation at Tucson, Ariz., for fourteen years. 



EROSION. 



The entire absence of a sod, a soil very slowly permeable when once 

 thoroughly dried, steep grades, violent windstorms, and torrential 

 rainfalls of short duration are the elements which are calculated to 

 produce erosion in its rao.st violent forms. Coupled with these natural 

 conditions, excessive stocking, with scarcity of water, compelling cat- 

 tle to travel long distances to feeding grounds over surfaces easily 

 pulverized, enhances very much the erosive action of the natural 

 elements. There always were deep gorges, cuts, arroyos, and washes 

 in the foothills, mesas, and other sections having steep grades; but the 

 cutting of the river channels into deep gorges which effectually drain 

 the bottoms instead of allowing the water to spread over the broad, 

 fertile lands is a distinctly modern condition, directly traceable to the 

 effect of the white man's operations. (PL V, fig. 2.) 



One of the most serious questions which confronts the rancher to-day 

 is how to prevent this gullying. While the loss of the land itself is 

 not, the loss of the water is a seriou.^; matter. The flood waters 

 which once spread over the river bottoms with practically no channel 

 are now sunken from a few feet to 20 feet below the surface, and are 

 carried off, together with all the rich sediment which they contain. 



Several ranchers whom the writer has met have been obliged, within 

 recent years, to devise means to mitigate this evil. It is often impos- 

 sible or impractical)le to do anything in those cases where the cutting 

 has progressed very far, but on the other hand it is not at all impos- 

 sible nor impracticable to prevent further depredation by attacking 

 the matter at the most advantageous point. The difliculty with work 

 of this kind is its expense compared with the productivity of the land 

 when no water is present for irrigation. 



