'Bui 25, Div. of Agrostology, U. S. Dept. of Agriculture. 



Plate XXIII. 



Fig. 1.— a ■■Wash" near Tucson, Ariz. The result of but Nine Years Erosion. 



From a photDgniph by D. (iriffiths. 



J 



Fig. 2.— The SiDE of the same ■■Wash," showing the Depth. 

 From a photograpli by I), (irifflths. 



