AMERICAN 3 
JOURNAL OF SCIENCE AND ARTS. 
[SECOND SERIES.] 
Art. XXXVI.—On some of the Mining Districts of Arizona near 
the Rio Colorado, with remarks on the Climate, &c.; by B. 
_ SILLIMAN.’ 
Tt 
1864, I visited the Colorado river for the por of seeing some 
e. he route followed 
was from Los Angeles in California by the Cajon Pass and Mo- 
camunga the journey is made by . 
from Los Angeles to the Colorado is about 250 miles, which. we 
The Mojave desert is entered at the summit of the Cajon Pass, 
where the road passes through a dug way in masses of sand- 
Stone, upturned hots of, probably, Tertiary age. The highest 
Poiat of this pass is (»y barometer) about 4000 feet above tide, 
f ; 
