Doc. No. 9.] 21 



FKOM POINT PIIS T OS TO THE NACISMIENTO EIVEK. 



The Coast Mountains extending from Point Pinos, Monterey, to the 

 northern line of Luis Obispo are mostly primitive ; the character of the 

 rocks which form the principle basis of these mountains are best observ 

 ed about Point Pinos and the town of Monterey ; they -are composed of 

 a coarse-grained but apparently firm granite, having a bluish grey color 

 where the solid masses have been recently fractured. In some places 

 this granite contains imbedded translucent crystals of felspar, (Adularia) 

 in others it is close grained, and contains but little mica, its disintegra 

 tion forming a fine white sand but little discolored by iron, and from its 

 brilliancy below the surface of the ocean, produces a most pleasing effect 

 on its waters at considerable distance from the shore. The light-house 

 at Point Pinos is constructed of this rock, and from the appearance of 

 the stone when properly dressed, it is highly probable that if the ledges 

 were properly opened, a good material for building purposes may be ob 

 tained and in sufficient quantities to supply all the local demands of this 

 country. 



The granite shows itself as an underlying rock for four miles into the 

 interior, from the coast, where it becomes covered with the debris of the 

 sedementary rocks resting upon it and alluvium, but there is but little 

 difficulty in tracing its course for forty-five miles easterly of Monterey ; 

 it becomes more largely developed after crossing the Carmello and enter 

 ing the mountains on its southern side. 



The trend of the Coast Mountains south of Monterey for fifty miles is 

 south 50 degrees east, while the strike of the granite rocks is at an angle 

 of nearly 18 degrees to the line of trend, or in other words cutting the 

 course of the ridge at an angle of eighteen degrees. The granite rocks 

 at Point Pinos are of the same series as those occurring in the vicinity 

 of the Eancho Piojo, and south of the Estella, thirty miles distant from 

 the latter in a southerly direction ; the texture of these rocks in these 

 southern localities is more compact than in the vicinity of Monterey, and 

 in some cases are hornblendic in their character. On the east the granite 

 is flanked by an extensive group of the Serpentine formations, which 

 continue south as far as the Mission San Antonio ; they constitute the 

 principle part of a ridge running parallel with the granite, and situated 

 between the latter and the Salinas Valley. The country over which the 

 magnesian rocks predominate is easily distinguished from that in which 

 granitic or trapean group is found, by the vegetation incident to both 

 the serpentine hills being generally destitute of the larger forest trees, 

 and covered with a thick " Chamisal" and stunted varieties of the oak ; 

 this peculiarity of these hills is very striking, and cannot fail to arrest 

 the attention of the traveler, either among the Coast Mountains or Sierra 

 Nevada, in passing over them. The talcose and chlorits slates of these 

 mountains were found to be auriferous in several localities, and mining 

 to a considerable extent was conducted in some parts of these mountains 

 during the past summer. 



The magnesian rocks cross the Nacismiento Eiver fourteen miles above 

 its junction with the Salinas ; on the banks of this stream they appear 

 in the form of massive Serpentine, but assume a schistose structure three 



