MESAS AND FOOT-HILLS 



195 



short ranges of barren mountains, that have 

 the general trend of the main Sierra Madre, 

 and it looks so much like the country to the 

 west of the river that it is usually recognized 

 as a part of the desert, or at the least ' ' desert 

 country." 



It is, however, somewhat different from the 

 Bottom of the Bowl or even the valleys of the 

 Mojave. The elevation, for one thing, gives it 

 another character. The rise from bench to 

 bench is very gradual, and to the ordinary ob- 

 server hardly perceptible ; but nevertheless when 

 the foot-hills of the Santa Rita Mountains are 

 reached, the altitude is four thousand feet or 

 more. There is a difference in light, sky, 

 color, air ; even some change in the surface of 

 the earth. The fine sands of the lower desert 

 and the sea-bed silts are missing ; the mesas lie 

 close up to the mountains and receive the first 

 coarse wash from the sides ; the barrancas on 

 the mountain - sides are choked with great 

 masses of fallen rock, with bowlders of granite, 

 with blocks of blackened lava. The arroyos 

 that carry the wash from the mountains mere 

 ditches and trenches cut through the mesas 

 are filled with rounded stones, coarse sands, 

 glittering scales of mica, bits of quartz, breaks 



Rising up 

 from tkt 

 desert. 



The great 



