UNITY OF CORDILLERAS AND COAST RANGE. 
91 
were noticed here. The order of segregation of the minerals observed in the granite of the 
canon of the Peyrou was as follows : 
Felspar (orthose) white and reddish. 
Hornblende crystals in felspar paste. 
Syenite, highly quartzose. 
Hornblende slate. 
Hornblende porphyry. 
Gneiss. 
The felspathic rock, a crystalline porphyry, being found on the west side, and as the river 
cuts its way further down it revealed the introduction of amphibole, until the whole rock 
assumed the appearance of a coarse gneiss or a hornblende porphyry. The granitoid rocks of 
San Emilio, of which those cut through by the Peyrou are the more depressed portions, cannot 
be less than from eight to ten miles thick upon the surface, and yields an immense amount of 
detritus to the Peyrou and other smaller streams which roll into the Santa Clara on its 
western side. 
The strata on the western slope of this upheaved region are those of San Buenaventura, which 
have been traced, as described, running into the Cordilleras. The strata on the eastern slope 
form the hilly country called Cestek, which, in appearance and vegetation, is the repetition of 
the strata which cover the east side of the Cordilleras at San Francisquita and Cajon^pass. The 
grass, the oak, the pine, the sycamore, and the cotton-wood disappear, and in its place are 
tule, yucca, palmetto, dwarf cedar, and the worthless vegetation of the desert slope. The sand¬ 
stones described as peculiar to the eastern slope stretch in and occupy the angle formed by the 
termination of the Sierra Nevada at the Canada de las Uvas and the San Emilio mountain, 
which lies fifteen miles west; this re-entering angle of the desert is crossed in the trail from 
Los Angeles to Fort Tejon. These sandstones dip away from the granitoid rocks of the Cor¬ 
dilleras at San Emilio, and so on toward Cajon pass, while they run abruptly up to, and lie 
unconformably upon the Tejon granites. This may be observed in the Cestek plain. It would 
thus appear that this sandstone was deposited originally upon both ranges, the Nevada and the 
Cordilleras, but that since the deposition the former was not upraised, while the latter was. 
Should this observation prove correct, it follows that the Cordilleras are of a later age than the 
Sierra Nevada ; a view which I think the correct one, although opposite to that taken by Mr. 
Marcou. Both ranges may be post-Miocene in appearance, and to some extent arose together, 
but the latest elevations have been in the Cordilleras and the Coast Banges, and the general 
order of upheaval, in point of time, from the east toward the west. 
Nothing appears easier to trace than the relations of connexion and continuity between the 
middle of the Coast Ranges (San Jose and Point Pinos) and San Emilio, and between San 
Emilio and the Cordilleras, a fact now, for the first time, stated and brought to light by the 
explorations of this survey, by which there has been traced a continuous granitic chain from 
Point Pinos, at Monterey bay, to the northwestern edge of the Cajon pass, terminating at the 
Kikal Mungo mountain; a range alike distinct in direction from the Sierra Nevada or the San 
Bernardino and Temecula ranges. 
The ranges which lie west of the San Jose sierra do not always run parallel with it. The 
Santa Lucia range gradually approaches it toward the south ; the San Rafael hills, a small 
chain.to the southwest, run in a trend somewhat more to the east, and the Santa Inez, the last 
ot the coast ranges, has a still greater deviation to the east; thus, by a gradual radiation, they all 
