MINING MAGAZINE. EDITED AND CONDUCTED BY WILLIAM J. TENNEY. ART. CONTENTS OF NO. II., VOL. III. ARTICLES. I. THE MINERAL REGION OF CENTRAL CALIFORNIA. BY PROF. II. THE EMPLOYMENT OF STEAM IN CERTAIN METALLURGICAL III. PRODUCT OF THE MINES, SMELTING FURNACES, AND SALT- PAGE 181 186 141 IV. EXAMINATIONS AND EXPLORATIONS ON THE GOLD-BEARING 168 Export of Mineral from Caldera, Chili English Lead Trade Gran Pobre Mine, Venezuela. Rivilla Silver Mining Company Mode of Treatment of Ores or Alloys of Gold and Silver Cost of Producing Iron in Scotland and Silesia, and the Most Improved System of Charcoal Smelting Crescent Iron Works Burning Brick with Cumberland Coal MINING MAGAZINE: DEVOTED TO Mines, Mining Operations, Metallurgy, &c. &c. VOL. III.—AUGUST, 1854.-No. II. ART. I. MINERAL DISTRICT OF CENTRAL CALIFORNIA.*—BY PROFESSOR JOHN B. TRASK. AFTER completing the examination of the coast mountains within the parallels alluded to, a visit was made to the mineral * Under a joint resolution of the legislature of California, passed May 6th, 1858, authorizing a further examination of some parts of the Sierra Nevada and coast mountains, Professor Trask entered upon the survey, and prosecuted it until the 28th of November ensuing, comprising a period in the field of about six months. The first five weeks were occupied in examinations of the more elevated and western portions of the counties of Butte, Sierra, Yuba, Nevada, and Placer, in determining, as far as possible, the position of an ancient water-course in this section of the State, and its peculiarities-the description of which will be found in the body of this report. On the 23d June the southern portion of the tour was commenced, and carried on almost uninterruptedly for four months. The route south was car ried through the counties of San Francisco, Santa Clara, Santa Cruz, Monterey, and the north part of Luis Obispo; on the west, and returning on the east (or through that range denominated the Monte Diablo Range), by the west part of Tulare County, Mariposa, Tuolumne, Alameda, Contra Costa, and San Joaquin. I The range of country bounded on the north by the Straits Carquinez, and south by the Nacismiento, was divided into four sections, formed by lines running nearly east and west from the great valley to the coast. On the first of October, the country north of the Straits Carquinez was entered, and prelim inary examinations only were made in the counties of Solano, Napa, and SoFrom the county of Napa a section was carried across the basin of the Sacramento, and connected with examinations made two years previous on its eastern edge. A similar section was also made, passing eighteen miles south of Monte Diablo, and continued across the San Joaquin. noma. The remainder of the months of October and November was employed in investigations of the middle mining sections of the county of Nevada, and those intermediate between the former and the middle and western parts of Calaveras county. The range leads through that section in which the princicipal gold mines of the middle portions of the State are located. The report was presented to the legislature in the spring, and we are under obligations to the author in kindly forwarding copies to us. The portion we herewith publish, in relation to the mineral district in the central part of the State, is of immediate practical value. The entire report occupies ninetyfive pages, and is the most valuable document which has yet appeared on the subject. districts, embracing parts of the counties of Nevada, Placer, El Dorado, and Calaveras, the objects of which, was to connect a line of travel commenced in May and June last, in the counties of Butte, Yuba, and Sierra; and to obtain, if possible, some information respecting the general character of placer and quartz mining at the present time, compared with its earlier prospects. Two years having elapsed since I had visited this section of the country, and having in my possession the original notes of travel and maps made at that time, with a general acquaintance of their former condition, it was deemed advisable to make this particular examination, in order to form some estimate on their future prospects. With this view, the more central portions of the mining districts were selected, as these may be considered a fair example of the extremes, and from the lateness of the season and distance were more accessible. PLACER MINING. The extensive excavations, which have been made within the last two years, in this branch of mining, has afforded an opportu nity of examining the different mountain formations not heretofore obtained, and has been the means of eliciting much valuable and interesting information relative to the early condition and mutations which have taken place in the superficial coverings of our hills. The rapid progress of advancement in the methods of conducting mining operations in this branch particularly, has opened a door for scientific research, which it seems impossible to have accomplished in so short a period as that in which they have been occupied; they have the appearance of having been in operation for half a century rather than the short space of four years. It is now ascertained to a certainty that the placer ranges extend to the east, within ten or fifteen miles of the "summit ridge," so called, of the Sierra Nevada; and the condition in which it is found at these points is similar in all respects to that in the older or more western sections, with perhaps one exception, and that the relative age of both. There are evidences which clearly indicate a deposit of gold older than the diluvial drift of the lower or western diggings, (which latter is often confounded with the drift deposits of the tertiary periods in this country,) the character of which differs in almost every respect from any other deposit yet observed in this country, except in this particular range.* This deposit appears to hold a position and age below the tertiaries, and may be considered intermediate between the latter and the primitive formations in this State. Its fossils differ from any thus far found, in any formation within the State, and I am disposed to refer it to the Brandon group of Vermont, discovered by Prof. Hitchcock, vide Silliman's Journal of Science. Its direction has been traced for about seventy miles, and is found to extend through the counties of Butte, the eastern part of Yuba, Sierra, Nevada, Placer, and El Dorado; it appears to have an average breadth of about four miles, with an elevation of four thousand feet above the sea for the greatest part of its length. From the examinations that were made upon this range, there are abundant evidences that an ancient stream flowed through this section of the country, and in a direction parallel with its then existing mountain ridges, and the extensive mining operations conducted in the south-east part of Sierra county on this range, has been the means of demonstrating this fact, which had heretofore been strongly suspected only. The outliers of its banks are very definitely marked throughout the entire length of the formation under consideration, and its former bed filled in many places with a volcanic sand and ashes, which probably accompanied its displacement. In the county of Sierra these peculiarities are best observed: in the vicinity, and for ten miles west of Downieville, the hills are covered with a volcanic brecia and tufa, which may be conveniently studied between the Negro Tent and Galloway's Ranch, also on all the hills and ravines surrounding Yumana on Oregon Creek. On the creek the tufaceous deposit is found to the depth of sixty feet. The exact point from which these immense quantities of volcanic material were ejected, is somewhat obscure; yet there are reasons for the supposition that they had their origin in the truncated cones which lie a few miles to the north-east, and of which the Pilot Peak forms one of the principal points or centres of this rugged and forbidding district. This presumption is based on the grounds that between Pilot Peak and Yumana there are ample evidences of a direct connection with these larger centres of disturbance; an extensive dike of black scoriaceous and vesicu lar lava is traceable throughout the entire distance between Yumana and the Pilot Peak, passing through the hill north-west of Downieville, and within two hundred yards of the town, it crosses the river at this point, and appears at Durgan's Flat on the opposite side of the stream; from thence it is again met near Galloway's Ranch, and continues from there to the high bluff which overhangs the town of Yumana, on Oregon Creek. There are no other true volcanic cones in this section that would seem commensurate with so large a scale of operations, except those above noted, though the minor peaks undoubtedly added much to the general result. The displacement of this ancient stream and the subsequent filling of its bed has opened a new and rich field for scientific research in this State, but its more direct and economical bearings are that it affords an equally new and extensive field for |
