CHAPTER XIII. 
GEOLOGY OF THE CORDILLERAS. 
Chain known by the name op cordilleras.—Direction.—Repetitions op the chain.—Passes.—Character op the oajon pass 
and san gorgono.—Altitude of the passes.—Conglomerate of the slopes.—Strata in the cajon pass.—Cause op the 
DIP OF THE STRATA.-DIFFERENT ASPECT OF THE CORDILLERAS VIEWED FROM THE WESTERN AND EASTERN SIDES.—AXIAL ROCKS OF 
THE CORDILLERAS.—STRUCTURE AT WARNER’S AND THE CAJON.- TlIE SEDIMENTARY STRATA ON THE WEST SLOPES.-PERIOD OF 
ELEVATION OF THE CHAIN.-SAN EMILIO MOUNTAIN.-GEOLOGY OF THE DISTRICT SURROUNDING.-TlIE MOST ELEVATED LAND IN 
SOUTHERN CALIFORNIA. PERU RIVER.—CANONS OF, THROUGH GRANITIC ROCK.—SEGREGATION OF MINERALS OF THE GRANITE. 
Cestek plain.—Sandstones of, conformable to the cordilleras but not to the sierra Nevada.—Relative modern 
APPEARANCE OF THE FORMER RANGE.—CONTINUITY OF SAN EMILIO WITH POINT PINOS RANGE.-RADIATION OF THE CHAINS FROM 
SAN EMILIO DISTRICT.-SANTA BARBARA CHAIN ELEVATED INDEPENDENT OF THE CORDILLERAS.-DIRECTION OF THE VOLCANIC 
FISSURES OF THE COAST RANGES. 
Under this term is included the mountain range which extends from the point of junction 
of the Sierra Nevada and the coast ranges to the Mexican boundary line, and thence southward 
into Lower California, of which it forms the spine. It is not, hy any means, a continuous 
chain, hut a series of disjointed masses running in a nearly parallel direction, the intervals in 
the chain being the passes from California proper into the desert. 
The direction of the Cordilleras is uniform. If a line he extended from San Emilio mountain 
in a direction south 50° east to parallel 34°, it will be found to cover the great mass of the 
range lying between these two points, the southern termination being the great mountain San 
Bernardino. The length of this range is about 150 miles. 
Temecula mountain, in 33° 30', commences another range, which extends south 45° east, 
and passes into the peninsula of Lower California. The observed length of this range was 80 
miles. The continuity of these two ranges is preserved hy the San Jacinto mountain, which 
lies between San Bernardino and Temecula mountains. 
The passes which occur in these two ranges, leading from the coast into the Great Basin and 
the Colorado desert, are— 
1. San Francisquito pass, (also called Turner’s pass.) 
2. New pass. 
3. Cajon pass. 
4. San Gorgono pass. 
5. Warner’s pass. 
Of these, only passes 1, 3 and 5 will be noticed here, as they alone were subjects of observa¬ 
tion. It may he doubted if passes 1 and 2 are true arrests of the upheaving power ; they might 
he more properly considered as alterations of denudation and fracture, produced in a continuous 
range hy actions occurring long posterior to the elevation ; while in the Cajon pass there is a 
wide separation of several miles between the lofty mountain masses of Kikal Mungo and the 
range prolonged northwest from San Bernardino, a separation so wide that, looking from the 
plain at any point south of the pass—as from the Mormon town—a wide passage can be plainly 
discerned between the ranges. The ranges are really connected hy the stratified sandstones of 
