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Show 159 At the ranch of Los Encinos the direction of the dip of the strata is north- northeast, at an average angle of 15°. These strata consist chiefly of light, grayish, pale- yellow, or chalky- white limestone rocks, in layers of a thickness varying from 2 to 3 feet; they are easily divided into slabs, with numerous dendritic impressions. The fossils are found chiefly in the upper portion of the group. These fish- bearing limestone rocks have evidently formed the entire bottom of the beautiful valley of San Fernando, as is shown by the hillocks or isolated mounds which have been left here and there in the plain by erosions, and on which remains of fossil- fishes and the Pectm Peckanii are found. I refer particularly to the mound by the side of the stage- route which leads to Santa Barbara. THE SIERRA OF SANTA MONICA. The San Fernando Valley is closed on the south by the Sierra de Santa Monica. The center of this sierra is between the ranches of Los Eucinos and of Santa Monica, or San Vicente, is formed of a gray syenite, composed of fine particles, * Sassing to a true granite, and easily ecomposed by atmospheric action. Dioritic rocks here and there intersect the syenite, and from massive dikes toward the crest of the sierra, on the south side of the chain. On these syenites rest large - grained sandstone rocks, scarcely ever more than 250 feet in thickness, and covered in concordance of stratification by the fish- bearing limestone rocks of Los Encinos. These sandstone rocks are sometimes asphaltic, and contain some fossils, especially the beautiful Pecten Vcatchii Gabb, and Pecten Wkipplei, new pieces. Beautiful specimens of these two large Pectines have been collected a little to the west of Los Encinos, at the Malaga ranch, by Lieut. C. W. Whipple, of the Ordnance Corps, who bad charge of one of our exploring parties. At the side of the principal house Q. of the Encinos ranch, at tne top of g. an isolated eminence, which over- § looks the basin of mineral- water, 2 numerous remains of vertebrae, ribs, | j and head- bones of an enormous fos- • ail cetacean are found. There also g are found the upper beds of this *, formation of white fish- bearing g* limestone. These beds are arranged g. in the form of calcareous lenticular g nodules inclosed in silex. These no- w dules are from 2 to 3 feet in diame- B ter, and, when opened, are found to g* contain fossil- fishes, fragments of bones of Cctacea, or plants. The Sierra de Santa Monica runs from west to east, and strikes perpendicularly against the granite and pegmatite of the Sierra Madre, on the other side of the cafion of the Rio de les Angeles or Rio de Por-ciuncula. This cafion itself has been I formed through this sierra, which < rises rapidly in the eastern part, j after leaving Cahunga Pass. From ' a height of from 500 to 600 feet the crests of the sierra suddenly rise to an altitude of from 800 to 1,000 feet on either side of the cafion of Los Angeles. Hills of sandstone and of fish- bearing limestone, identical with the beds of the section near Los Encinos, fill the eastern extremity of the San Fernando Valley, and rise against the granite of the chains of the Sierra Madre at the entrance of the large |