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Show 183 As I have demonstrated the presence of cobalt and nickel in basalts of New Mexico, ( see survey reports Vol. Ill,) I searched for these elements in the California basalts, and was surprised in finding small quantities of them, widely distributed. At first one might form the conclusion that their presence is due to the olivine, a mineral which contains nickel as a normal constituent, as shown by Stromeyer, but a closer examination will refute this hypothesis, as the basalts of Southern California contain but rarely olivine as an accessory constituent. I am of the opinion'that these elements are connected with the magnetic iron of the basalts, and this idea is sustained by the fact that npon digestion of the finely pulverized rock with concentrated hydrochloric acid for from six to twelve hours the whole of the nickel and cobalt is with the iron in the solution, while the labradoritic and pyroxonio particles are but little attacked. If the acid solution thns obtained be freed from most of its acid, then supersaturated with ammonia, filtered, evaporated, ignited, and the residue treated with dilute hydrochloric acid, the presence of cobalt and nickel may be easily demonstrated by the oommon methods. Among the rocks and tufas tested I found the respectively largest proportion in the tufas of the trachydolerites of the island of Santa Cruz. Zara.- Vesicular lava, of apparently very modern date, was observed at Camp Cady, in the Mohave River Valley, and at the southeastern margin of Owens Lake. Are we now justified in assuming that with the lava outbursts the piutonic powers left their favorite theater, or have retired to seek another field of activity f The circumstances do not testify to the affirmative of such an assumption, for frequent rumblings indicate the existence of latent volcanic powers. In the vicinity of Owens Lake hardly three weeks pass without a slight - shock being felt. The most violent shock remembered by the settlers in the Owens River Valley took place at 3 p. m. of the26th of March. 1872, reaching from Owens Lake north as far as Aurora, Nov., a distance of about 130 miles. The changes thereby produced at Owens Lake are still visible. I saw the fractures of the earth, now partly filled with sand, the stratum of sandstone raised 14 feet, and a spriog prodnced by uewly- formed fissures. Huge masses of rock became detached on the east side of the Baena Vista Mountain and hurried thundering down the slopes. At the village of Lone Pine resulted most terrible effects; the dwellings were thrown down and sixty persons killed in a twinkling of an eye. Similar effects, but on a smaller scale, were experieuced at Independence. The vibrations lasted several seconds, and the noise resembled that of a train of heavy wagons hurrying over a stone pavement. At ban Diego and Fort Yuma, in Southern California, the shocks average nine per annum. The most violent in the memory of the whites was that of November 9, 1852, with a great frequency of subsequent shocks, lasting for about two months. Professor Blake reports that a portion of Chimney Peak was thrown down, and cracks and fissures opened in wide circumference of Fort Yuma. Forty miles sonth from this post a number or mud volcanoes were formed, whose waters had a temperature of 170° F. The frequency of earthquakes did not fail to be noticed by the early Spanish visitors. Sebastian Viscaino said, ( 1596:) " No es el mar peligroso es su costa tierra muy tem-plada." ( It is not the sea that is dangerous, it is the trembling coast.) GENERAL GEOLOGICAL HISTORY OF SOUTHERN CALIFORNIA. This is, in a few words, as follows: The country was partially submerged during the Azoic period, and, probably, with repeated changes of level, partly during the Palaeozoic, began to rise and remained above water until toward the close of the Cretaceons, when it sank to a great extent below the ocean and remained there up to the middle Tertiary: began then to rise, and reached finally a level so far above the present one that the islands now separated from the coast by the Santa Barbara Channel formed part of the continent, as is indicated by the elephants' teeth* found on them, and by the occurrence of a small fox derived from the continental fox by gradual transmutations. Toward the close of the Tertiary the country was the home of the buffalo, horse, rhinoceros, llama, tiger, and mastodon. t That brilliant age experienced, however, a great series of volcanic disturbances that had commenced early in the Tertiary, and continued np to quite modern date, in longer or shorter intervals. With the decline of the Tertiary, the country sank again until the mountains projected as mere cliffs above the ocean. Mighty currents agitated the waters and assisted in forming the Quaternary conglomerates. The Quaternary period was so far advanced that the glacial epoch had passed its zenith, when the country emerged once more from the watery grave to salute the vivifying sunbeams. The coast is still rising at the Sresent day, at a rate of about 5 feet per century, and, as the Santa Barbara Channel as 60 fathoms depth, the islands off the coast will, in seven thousand two hundred years, be again united with the main land, if the rise thus continues. It is, however, * See Proceedings of California Academy of Sciences, 1873. t See article of Professor Leidy in the Proceedings of California Academy, 1873. |