H, Doc. 129. . 21 



Anomia and Pecten ;. while on the west side, bordering the Pacific, 

 there is a greater variety of genera and species ; shells of the genera 

 Cardium, Nucula, Corbula, Tellina, Mactra, Naricaand Trochita being- 

 abundant. An interesting relationship between the existing and fossil 

 shells of the Gailf side of the chain is indicated, and it is probable 

 that the crest of the chain divided the waters of the Gulf and the 

 Pacific during the Miocene era. 



At the pass of San Fernando, between Los Angeles and the gra- 

 nitic mountains, the sandstone strata contain numerous fossils, and 

 fragments of shells belonging to the genera Ostrea, Pecten, and 

 Turritella were procured. These, being imperfect, have not been 

 specifically described by Mr. Conrad. 



At Navy Point, Benicia, I obtained several casts of shells in an im- 

 perfect state, and, also, a small shark's tooth. The shells were pro- 

 bably of the genera Trochus and Turritella. Numerous specimens of 

 lignite were also found at that place, imbedded in the compact sand- 

 stone. 



At San Francisco, on the west side of the peninsula, near the 

 lagoon on the beach, numerous specimens of fossil Spatangi are 

 thrown up by the surf. They are inclosed in a matrix of bluish-green 

 sand, resembling in color and composition the blue sandstone of the 

 bay. It is, however, more friable, and seems to consist of the debris 

 of the strata. 



The town of Monterey is built over the line of junction of the 

 granite of Point Pinos, with an extensive series of tertiary strata, re- 

 markable for containing immense deposits of the remains of Infusoria. 

 These remains form white beds of siliceous earth, intercalated with 

 semi-opaline strata of a very compact texture. They are now up- 

 raised nearly 500 feet above the water of the bay. Portions of the 

 underlying strata those in which the Tellina congesta, Con., occurs 

 so abundantly are also charged with small chambered shells, (Poly- 

 thalamia, Foraminifera of D'Orbigny,) and offer a rich treat to the 

 micro-geologist. With the aid of a glass thousands of these little 

 shells can be seen on the fractured surfaces of the rock. 



From this report, and the preceding remarks, it will be seen that 

 fossils in sufficient numbers to determine the geological age of the de- 

 posits in which they occur have been obtained from many and dis- 

 tant points on the Pacific coast. 



The occurrence of Eocene strata at one point has been satisfactorily 

 established. We also find that the Miocene division of the tertiary 

 formations is extensively developed, over broad areas, in California, 

 flanking nearly all the great lines of elevation, not only in the coast 

 mountains, but in the interior, along the borders of the San Joaquin 

 and Tulare valleys. Further observations are required to connect, 

 chronologically, the Miocene deposits along Ocoya creek with the ex- 

 tensive, and in many respects similar, strata further north, along the 

 Tuolumne and Stanislaus rivers. 



