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Show 198 CONCLUSION AND REMARKS. On subjecting the surface- conditions of California to a critical examination, one cannot fail to be struck forcibly by the great number of thermal springs; indeed, there are few countries in the world with such a large number upon an equal area. It is true, Montana and Idaho, with the famous geyser- regions, first explored by Lieut. W. Doane- then Colorado and New Mexico- contain also a considerable number, and still above them Nevada; but these Territories have more or less similar features as California in regard to the extensive volcanic formations. There is no doubt that a close connection exists between the latter and the thermal springs; both are due to the fact that the earth- crust covering the molten interior is thinner than elsewhere. Waters, after penetrating this crust, become heated, charged with salts, and are driven through other fissures to the surface by the power of the generated steam. In connection with this relatively thin crust stands the great number of earthquakes felt annually in California. Alexander von Humboldt says, in the description of his travels through the equatorial regions of South America, that " the hypothesis of the relation between the volcanic formations and the existence of th ermal spriugs seems not to be well founded;" simply because he encountered springs of nearly boiling temperature issuing from Azoic rocks at Mariara, on the Orinoco. He certainly would have formed a different opinion had he traveled through New Mexico, Nevada, and California, where gigantic peaks and wide- spread flows of volcanic material form most prominent features. It may safely be assumed it is rather the exception that thermal springs issue within very large distances from volcanic formations. In Southern California thermal springs are found at Santa Barbara, San Juan Capis-trano, San Diego, Yuma, San Bernardino, Benton, in Ooahuila Valley, Long Valley, Death Valley, Fanamint Valley, Salinas Valley, in the Coso Range, at Kernville, and Caliente. A number exist also in Northern California, among them several far- famed geysers. Strange to say, most of these thermal waters contain comparatively small quantities of mineral constituents; indeed, less than many of New Mexico. Generally they contain carbonate of soda, a notable exception from those of San Bernardino; this salt is accompanied by sulphate of soda and chloride of sodium, in varying proportion. Carbonate of lime, with some carbonate of magnesia, form, in most of the cases, an additional mixture, while silicic acid never is wanting entirely; its quantity, however, is not considerable. As a general rule, the amount of potassium salts falls far behind that of sodium salts, which is probably due to the fact that the former are retained by the strata traversed. It is well understood how quickly potassium salts are absorbed by the soil in such a manner that water cannot wash them out. One of the most remarkable thermal springs ia that discovered by Lieut. Rogers Birnie, jr., heretofore mentioned. It has an intensely sour taste, due to free sulphuric acid, and, besides, it contains the sulphate of potassa, soda, lime, magnesia, alumina, and oxide of iron. The presence of small quantities of nitric acid and ammonia may be due to the formation of ammonium nitrite from water and nitrogen of the air, and to the immediately following combination of the ammonia with the sulphuric acid; thus the redecomposition of ammonium nitrite, taking place BO readily under ordinary circumstances, being prevented. With regard to the cold mineral springs, that of the Little Tosemite deserves especial mention, being the only soda spring with a notable quantity of iron. Next to this one, the soda spring of Encino Rancho, and the sulphur spring of San Fernando Mountain, are of medicinal value. The brackish and bitter springs generally contain sulphate of magnesia, sulphate of soda, sulphate of lime, and chloride of sodium or magnesium; these. waters, although mineral springs in a wider sense, are repulsive to taste, and men and animals avoid to drink of them, while springs of a character like that of the Little Yosemite are eagerly drunk, and preferred even by animals to ordinary water. The Mohave Desert, like many other deserts, abounds in such bad waters, the horror of the tired, thirsty traveler. Bitter springs and brackish waters were encountered in the mountains 20 miles north of Callville, in Southern Nevada, at Miningtown Mineral Park, in Northwestern Arizona, at Dos Palms, and thence 5 miles west from there, m San Diego County, on the saline flats of the Mohave, and, above all, in the Virgin River. A fact of no little interest is the occurrence of a number of lakes in Eastern California that contain as main constituent carbonate of soda. These lakes, and a number of alkaline and saline flats, are situated east of the Sierra Nevada, and west of the great parallel ranges known as the White Mountains, Inyo and Argus ranges, which are filled with splendid fissure- veins. The alkaline lakes are Owens Lake, Mono Lake, Black Lake, and the slough of Bishop Creek. In addition to this chapter, the notes on mineral and thermal springs visited by Mr. Douglas A. Joy, who was attached as geologist to the Division No. 2, in command of Lieut. W. Whipple, may find a suitable place. To Mr. Joy I am indebted for the following communication: |
