UNITY OF CORDILLERAS AN]) COAST RANGE. 91 



werfe noticed here. The order of segregation of the minerals observed in the granite of the 

 carton 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 Caiiada 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 liave been in the Cordilleras and the Coast Kanges, 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 Eanges (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 soutliwest, 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 ; tlius, by a gradual radiation, they all 



