45 RESOURCES OF CALIFORNIA. 
‘ Sierra Nevada. The largest of these is in Tuolumne county, 
about three thousand feet above the sea, and one hundred 
miles eastward from San Francisco. It is thirty miles long, 
three hundred to eight hundred feet high above the surround- 
ing country, and about a quarter of a mile wide, in many places 
less. The basaltic formation is evident at a distance, from the 
perpendicularity of the sides near the top, and the flatness of 
its summit, gently descending toward the west. Along the 
sides of the Sierra Nevada, near the line of separation between 
the sandstone of the valley and the granite of the higher parts 
of the Sierra, are found various other rocks, among which 
slate, quartz, and limestone, are prominent. The slates are 
usually soft, their cleavage often perpendicular to the horizon. 
Limestone is abundant about two thousand feet above the sea, 
between latitudes 37° 30’ and 39°. It is all metamorphic, and 
some of it is a fine marble, which may prove of value for stat- 
uary. Most of it is gray m color. Metamorphic limestone is 
also found near Santa Cruz, near New Almaden, at Monte 
Diablo, and in Shasta and Siskiyou counties. It is said that 
some stratified secondary limestone has been found in Shasta 
county, but this is a matter of doubt. No secondary coal has 
been found in the state. Tertiary coal, much of it a lignite, 
has been found at various places in San Diego, Santa Clara, 
Alameda, San Francisco, San Mateo, Contra Costa, and So- 
noma counties, and much money has been spent in opening 
veins. 
§ 35. Diluviwm.—tThe Sacramento and San Joaquin valleys 
are covered with a diluvium from four hundred to fifteen hun- 
dred feet deep. It is composed of alternate layers of sand, 
gravel, and clay. The most complete information which we 
have as to the nature of this diluvium is given in the report 
of the boring of an artesian well, one thousand feet deep, at 
Stockton. This is, I believe, the only artesian well in the Sac- 
ramento Basin; at least, it is the most notable one. An at- 
tempt was made to bore an artesian well in Sacramento, but 
the auger struck a stratum of boulders about four hundred feet 
