a 
INTRODUCTION. 13 
staff it is twenty-four inches and over the greater portion 
of the country as much as 10 or 15 inches. Along the 
lower Gila, however, it is as little as 1 or 2 inches, re- 
sulting in a veritable desert. 
Distribution of Forests and Rainfall. Shaded Portion Indicates 
Timber and the Black Lines Rainfall Areas. 
The vegetation, needless to say, varies with the 
altitude and the rainfall. On the higher mountains 
and the more elevated plateaus are great forests of 
yellow pine with occasional Douglas spruce. The 
middle elevations are clothed with smaller trees, such 
as the pifion, a dwarf pine, cedar, juniper, and cypress. 
Small-growing oaks and mesquite bushes are also 
