17 







pounds; it is far superior in size to those found in the vicinity of Livermore's 

 ranch, in the county of Alameda, and like them, they at times have been found 

 to contain the impress of the animal that formerly inhabited the shell ; it is not 

 improbable that the age at which both species existed was contemporaneous, the 

 difference in species, size and form, being attributable solely to local climatal 

 effects. Such is the fact at the present time with the Mollusca inhabiting our 

 coast, within the parallels of latitude inclusive, and we have no reason that such 

 was not the case in relation to the fossiliferous groups. 



The large bivalves form an interesting feature in the paleontology of our 

 State, and undoubtedly are of different species from many already known in 

 other parts of the world; but their peculiarities must be deferred until a fu 

 ture period. 



The area over which the tertiary rocks are distributed, leaves but little 

 room for doubt of the former submergence of the entire district; and the dif 

 ferent periods of this era points us to so many successive elevations, which were 

 probably gradual in their character If it should be questioned that this was 

 not the fact, during the earlier age of these deposits, we would simply refer the 

 observer to the terraced outlines of the fossiliferous groups from the present 

 shore of the ocean to the summit of the first and western ridges of the chain. 

 These elevatory effects have undoubtedly been continued through the subsequent 

 periods of this epoch, and will be considered more in detail when the coast line 

 of the southern part of the State is under consideration. 



PRIMITIVE ROCKS OF THE COAST MOUNTAINS. 



The primitive rocks of the Coast Mountains consist of the granitic series, in 

 which are included the the Sienites, Micaschist, Granite, Gneiss, Porphyries, and 

 the older Greenstone, including also the serpentine rocks. On these rest the 

 greater part of the older sedimentary rocks, and some few of the Pliocene period. 

 Their general distribution has been noticed in the preceding pages qfithis report, 

 and it remains now only to mention more particularly the points at which they 

 may best be observed, with any peculiarities that may attend them. 



The granite forms the summit of a high ridge to the east of the San Inez 

 Valley; from about half the southern centre of the valley, and on the flanks of 

 the mountain, the serpentine rocks creep out and extend in a southwest direc 

 tion for about two miles, crossing the ridge at this point and forming its summit 

 for about half a mile. The entire line of this summit is bare and jagged, and 

 the white appearance of the granite at a distance gives it the aspect of a large 

 bed of quartz ; a closer approach, however, developes its true character. I 

 have seen but one other bed of the granite rocks of this State which presents 

 the same peculiar features, and those are situated about half way between the 

 town of Jackson and that of Volcano in the County of Amidor. In the middle 

 portions of the comb of this ridge is a large bed of Micaschist, containing 

 imperfect specimens of garnets which closely resembles those found on the Car- 

 mello Creek, in the County of Monterey. 



On the sides of these ridges and fronting the southwest, the sedimentary 

 rocks are found in detached masses, with imbedded fossils which are usually very 

 imperfect, and therefore, of little value; their distinguishing features fixing their 

 alliance to the Monte Diablo group. They maintain a high angle of inclina 

 tion in most instances, and have suffered much disturbance from the subsequent 

 intrusion of later igneous rocks through and among the primitive series on which 

 they rest; many evidences of the intrusions are manifest thronghout this entire 

 range, but as a general fact, they appear much more local in their character 



