It is true that one standing upon the dividing ridges of the Rio Grande, Arkansas, Colorado or Platte, is charmed by the views presented of far reaching plains and noble mountains, but it is doubtful if any one view can be found in North America so grand and thrillingly sublime as may be seen in the Sierra Nevadas. The scenery of the Yellow Stone and of the Colorado canyon have characteristic wonders that are sui generis; but those localities are not desirable for continuous occupation.
CHAPTER XX.
Golden Theories and Glaciers.
The many inquiries that the author has received concerning his views upon the gold deposits of California, has induced him to add this chapter to his work.
It has been said by an earnest and astute observer, that “The cooled earth permits us no longer to comprehend the phenomena of the primitive creation, because the fire which pervaded it is extinguished,” and again that “There is no great foundation (of truth), which does not repose upon a legend.” There has been a tradition among the California Indians, that the Golden Gate was opened by an earthquake, and that the waters that once covered the great plain of the Sacramento and San Joaquin basins were thus emptied into the ocean. This legendary geology of the Indians is about as good and instructive as some that has been taught by professors of the science, and as scarcely any two professors of geology agree in their theories of the origin and distribution of the gold in California, I have thought it probable that a few unscientific views upon the subject will interest my readers.
The origin of the gold found in California seems to me to have been clearly volcanic. The varying conditions under which it is found may be accounted for by the varying heat and force of the upheaval, the different qualities of the matrix or quartz that carried the gold and filled the fissures of the veins or lodes, the influence that resistance of the inclosing walls may have exerted when it was slight or very great, and finally the disintegrating influences of air, water, frost and attrition of the glaciers, and the deposition in water.
The theories of aqueous deposit (in the lodes) and of electrical action, do not satisfy my understanding, and I go back in thought to the ten years of observation and practical experience in the gold mines, and to the problems that were then but partially solved. Looking at California as it is to-day, it will be conceded that its territory has been subjected to distinct geological periods, and those periods greatly varying in their force in different parts of the State. Within the principal gold-bearing region of California, and especially along the line of or near the Carson vein or lode, coarse gold has been found, and in such large masses, free of quartz, as to force the conviction upon the mind that the gold so found had been thrown out through and beyond its matrix into a bed of volcanic ashes, very nearly assuming the appearance that lead might assume when melted and thrown in bulk upon an ash heap. Where the resistance was great, as when thrown through wall rocks of gneiss, or green stone, the liquefaction of the quartz seems to have been more complete, and the specific gravity of the gold being so much greater than that of the quartz, its momentum, when in large quantities, carried it out beyond its matrix, leaving the more diffused particles to be held suspended in the fast cooling quartz, or to settle into “pockets,” or small fissures.
Prof. Le Conte says: “The invariable association of metaliferous veins with metamorphism demonstrates the agency of heat.” Experiments of Daubre and others prove that water at 750° Fahr. reduces to a pasty condition nearly all rocks. Deposits of silica in a gelatinous form, that hardens on cooling, may be seen at some of the geysers of the Yellowstone; the heat, no doubt, being at a great depth. Quartz, like glass and lava, cools rapidly externally when exposed to air, or a cool surface, and would very readily hold suspended any substance volatilized, or crudely mixed into its substance. Its difficult secondary fusion is no obstacle to a belief in the capacity of heat under great pressure, to account for the phenomena that may be observed in the gold mines. Ashes derived from lavas have been found rich in crystalline substances. Crystals and microliths, and pyrites in cubes are, no doubt, of volcanic origin. The eruptions of moderate character seem to be the result of igneous fusion, while those of an explosive type are probably aquæ-igneous.
It is altogether probable from experiments tried by Stanislas Muenier and others, that the sudden removal of pressure is a sufficient cause of superheated water and mineral substances flashing into steam and lava. The geysers are evidently formed by varying temperature and interruption of flow by removal of pressure. Mr. Fanques, in an article in the Popular Science Monthly for August, 1880, says: “Discovery of microliths enclosed in volcanic rocks is a proof of immediate formation of crystals.”