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When the State geologist shall have completed his labors and issued his reports through the press, we shall be in possession of many facts which will elucidate and perhaps reconcile many apparent contradictions now to be observed in the formation of these deposits. Mr. Goodyear, one of Professor Whitney's assistants, in a letter to the Mountain Democrat, thus foreshadows a new theory:

With reference to the general question of the origin and distribution of the auriferous gravel itself there have been no end of theories, and every agency that is capable of moving rocks, from salt-water oceans to enormous glaciers and floating icebergs, has been called in to account for the phenomenon. With reference to most of these theories, it will only be necessary here to state the fact that no well-informed man can study carefully for himself in the field over any considerable extent of this country the character and distribution of the gravel, and the detailed structure of the banks with the fossils which they contain, without being led to the irresistible conclusion that there is but one possible agency which is at all capable of satisfactorily accounting for the complex and intricate phenomena, and that this is to be found in the action of fresh and running water. This agency was involved in the old "blue-lead theory" which has been for so many years a favorite, not only among the best-informed practical men, but among leading geologists and mining engineers as well. The gist of this theory may be stated in a few words by saying that it involved the supposition of the former existence here of a great river with its branches, the main trunk of this river being supposed to hold for one or two hundred miles, if not more, a general southeasterly course, nearly parallel with the present main crest of the Sierra, before the mountains were uplifted. But the detailed and extensive explorations of the gravel mines which have been made during the past two years by the State geological survey, have developed among other things the fact that this theory, too, is not only inadequate to account for the complex facts, but that it is not unfrequently in direct conflict with them. The questions involved are extremely complex, and it is no wonder that in the absence of systematic and extensive investigation of the facts in the field, the theories at first propounded should have been wide of the mark. And our own work in this direction is by no means as yet complete. What the true theory is, therefore, it would be premature for me to attempt to develop here. But it is rapidly assuming shape in our minds, and the whole subject will be thoroughly discussed in the forthcoming volumes of the geological report of Professor J. D. Whitney, provided the coming legislature shall furnish the requisite means for their completion and publication.

The limestone belt.-Placer mining. - Another prominent feature in the geology of this part of the country is the limestone belt, on which are found the early placers, noted for their immense yield from 1850 to 1855. This belt runs through all the southern mining counties, and can be traced continuously for nearly one hundred miles. Its course is northeast and southwest, and its width varies from half a mile to three or four miles, in some places contracting, at others expanding. At Sonora it is narrow, while at Shaw's Flat and Columbia, a few miles farther north, it is several miles in width. Throughout its entire length it was noted for the richness of its placer deposits, which were, however, merely superficial, rarely exceeding in depth six or eight feet, except in places where the limestone formation contracts, and at these points it has been worked to a depth of from forty to one hundred feet by following and cleaning the crevices. Throughout its length the limestone bed-rock has been deeply worn by the action of swiftly running water carrying bowlders and débris, which have cut and carved it in the most singular and fantastic shapes to a depth of many feet. In many places remarkable underground caverns of unknown extent are found. One of these exists near Cave City, El Dorado County, of many acres in extent, which has never been thoroughly explored, although discovered as early as 1852. The rich flats near Columbia and Springfield, when discovered by the early prospectors, were covered with dense growths of pine, and the entire face of the country has been so changed by mining operations as to be unrecognizable to the miner of '49-'50. The richest portion of the limestone belt has been found on the east side of Table Mountain, in Tuolumne County, and it is very probable that the placers owed much of their wealth to the scattering and distribution by water of portions of the Table Mountain channel not protected by lava. There is strong evidence of the correctness of this opinion near Springfield, Columbia, and Shaw's Flat all of these-places being but slightly below the level of the ancient channel at its exposed points. These towns, and Sonora, Jamestown, Montezuma, and Chinese Camp, owe their existence to this class of placers. Near the head of Table Mountain, where the basins and crevices on the limestone belt are deep, we find the towns of Murphy's and Vallecito, in Calaveras County, where mining is still prosecuted on a small scale by means of whims and pumps, with a fair profit, but the ground remaining to be worked is limited. At these points the Table Mountain is much broken up and loses its identity as a continuous range. The "flats" between the mound-like elevations have proved exceedingly rich, but all efforts to drain them have proved pecuniary failures in consequence of the great length of tunnels required. The towns of Columbia, Springfield, and Sonora, once the most populous of the southern mines, were built on the best placer ground, and town lots are now more valuable for mining purposes than for business and residence. Placer mining in their vicinity has been virtually abandoned to the Chinese, who are satisfied to work ground which has been passed through the sluice-boxes two or three times. It often happens in these towns that a lot with a brick house on it is bought and the house torn down, merely for the purpose of taking the gold from the ground. As some of these towns are very much decayed, property of this kind can be bought for prices which leave an ample margin of profit after sluicing out the ground. In confirmation of this statement, the following item from the Sonora Democrat of April 15, 1871, is given:

The fine brick store occupied so many years by Condit has been taken down with the store-room next south of it, and now the brick building next north is being taken down for the purpose of mining the ground under it. Every day pieces of quartz are found that are very rich in gold. The store was built on ground that had not been mined; it is proving so rich now that a mining hole will soon take the place of the building. Pieces containing from one to three hundred dollars each have been taken out within a week. One week's washing has averaged $10 per day to the hand employed, running one wheelbarrow, and only as yet washing top dirt. Several pieces were found ranging from one to three ounces; 12 wagon-loads (to test the claim before erecting sluices) paid him $150. In the rear of this same building, a few years since, one 25-pound chunk was found, and several of nearly that weight. A dog, digging for a gopher, at one time scratched out a piece of quartz for which Mr. C. obtained $70. Small pieces of float quartz are now daily found in this claim containing from $1 to $10 in free gold.

In fact, it would doubtless prove a paying investment to buy the land on which several of these towns are situated, tear down the buildings, and-sluice off the ground. The town of Sonora, however, has other resources, and is now experiencing a return of its former prosperity through its great agricultural and horticultural interests and the numerous quartz-mining districts of which it is the basis of supply.

MARIPOSA COUNTY.

This is the most southerly of the counties included within the limits. of the "southern mines." The placer interests of the county have been neglected for years, but this branch of mining will be revived with the introduction of water, for which purpose several ditches are being constructed.

The quartz interests show marked improvement, manifested by the opening of many mines abandoned for years, the discovery of new ledges, and the investment of San Francisco capital in developed mines. The mines belonging to the Mariposa estate are so situated that they require water for milling purposes; the mines are proven to be abundantly rich and comparatively inexhaustible, but cannot be worked successfully the year round without taking the ores to the Merced River. They now propose bringing the river to the mines, and the long-talkedof Mariposa ditch, located in 1852, is no longer a myth but a fixed fact, as the work is being actively prosecuted by the company.

Of the celebrated Mariposa estate and its mines there is nothing this year to be said. A new set of legal complications has paralyzed operations, but will terminate, it is believed, in a complete reorganization free of incumbrances.

The county of Mariposa possesses many valuable claims outside of the boundaries of the Mariposa estate, some of which are among the most productive in the State. Among these we may instance the Ferguson mine, the Eclipse, and Hites' Cove mines.

The Ferguson mine has recently been sold to an English company for the sum of $100,000. It is situated on the main fork of the Merced River, not far distant from the Yosemite Valley. The company own 3,700 feet, and intend erecting powerful machinery, as there is waterpower enough to drive an unlimited number of stamps. This mine has been in successful operation for over ten years without levying an assessment, and during the present year has paid dividends of $4,000 per month with an eight-stamp mill. The vein is from 1 to 8 feet thick, averaging 24 feet. The average pay of the rock is now about $44 per ton. Their tunnel is in 1,100 feet, on a level with the mill, to which the rock is easily taken by car. At the back of the tunnel they have sunk a shaft 100 feet deep; at this point it is 800 feet below the surface.

The Hites' Cove mine (described in report for 1871) is engaged in driving a cross-cut which is expected to reach the lode in May, 1872. This cross-cut will give them three hundred feet of backs. This mine has always paid large returns to its owners.

The Washington mine has a large vein and supplies a forty-stamp mill. It has never levied an assessment, but has paid for all improvements from its opening.

The Francis mine is a notable instance of a successful mining operation without capital. Mr. Francis, the recent owner, purchased the mine six years since on credit, and erected on it a five-stamp mill. The mine and mill soon yielded its owner a large advance on the original cost. The mine has recently been purchased by parties in San Francisco who propose erecting a sixty-stamp mill, as the mine has been developed sufficiently to warrant it, having three years' ore in sight and opened up. The lode is from 4 to 12 feet thick, and is traceable for miles through the country is opened by an adit level driven on the mountain side on the lode with constantly increasing backs. The rim will pay in free gold milling process from $12 to $15 per ton, with from 10 to 60 per cent. of sulphurets, worth from $100 to $300 per ton. The pay chute is of unusual length, and is already traced and tested for 1,900 feet. The company have 3,000 feet of lode.

There are many other mines in the county in various stages of development, but their opening has been retarded by the unfortunate condition of the Mariposa estate, which has been erroneously supposed to contain the best mines in the county, and which, considered abroad as an un-. successful example of mining on a large scale, has proved detrimental to all attempts to induce capitalists to invest in this county. The condition of this estate is to be attributed to the mismanagement incident to the control of all large and unwieldy corporations whose stock is elevated or depressed at the pleasure of operators who never saw the property of the company, and feel no interest in its development beyond the temporary enhancement or depression of the value of shares in the stock market for the purposes of speculation.

This state of affairs, however, will not be of long duration, as the resources of the county in gold-bearing quartz have attracted the attention of some of the leading mining operators of San Francisco, who have purchased several mines and are now engaged in the development of the long-neglected wealth of this county.

TUOLUMNE COUNTY.

This county, adjoining Mariposa on the north, has an area of 915,000 acres, of which but a small proportion is under cultivation, although the soil of the western portion of the county, from the foot-hills to an elevation of 2,500 feet in the Sierras, is unequaled in the productiveness of its orchards and vineyards, both as to the quantity and flavor of its fruits. The county has promising quartz interests which have for a few years past been dormant, but are now reviving under the impulse of successful operations in this branch of mining, while gravel-mining at various places on Table Mountain has proved, under good management, both safe and profitable as a business.

Chinese Camp. -The town of Chinese Camp is situated in a basin or flat, east of Table Mountain, at an elevation of 1,300 feet above sealevel, the Mother lode lying about one mile east of the town. The present population does not exceed five hundred persons, of whom three-fifths are Chinese. The main interest of the place has been placermining on the flat on which the town is situated. The ground has been worked over to bed-rock, a depth of three to five feet, and the best part exhausted, although the Chinese still carry on mining on a small scale when they can find dirt paying one dollar a day to the hand, of which enough remains to last for several years. The supply of water is limited, rarely more than one hundred inches being available, and this is sold at fifteen cents per inch for ten hours' use. Great difficulties were met with in obtaining an adequate supply of water for this place, as a deep ravine (Wood's Creek) ran between the town and the nearest ditch. These were finally surmounted by running a pipe, eleven inches in diameter and one mile in length, from the Phenix Water Company's reservoir across the ravine of Wood's Creek to a hill above the town. The head of the water-supply (at the reservoir) is two hundred feet higher than the discharge-box on the hill above the town, and an intervening depression-the ravine of Wood's Creek-having a depth of seven hundred feet, measured from the discharge-box, has been overcome, not by the construction of an expensive trestle-work, as was formerly the practice in carrying water over depressions, but by laying the pipes on the surface and relying on the pressure. Two hundred inches have been safely run through this pipe. The gold found here is noted for its fineness, and is probably the result of the breaking up of old channels, of which remnants are found on the edges of the basin. The pay-dirt extends entirely across the flat or basin, a distance of nearly three miles. Some spots proved very rich, but were quickly exhausted, and the future of this class of mining is not promising.

Detached masses or patches of cemented gravel are found on the summits of a few mounds or spurs of hills in this basin. These patches, on account of their hardness, seem to have resisted the disintegrating influences of air and water, which have swept away and scattered the original deposit of which they formed a part, depositing the released gold in the adjacent gulches and streams and over the flat. They are but isolated monuments, indicating the existence, ages since, of an extensive belt of gravel deposited by the action of water, but whether in the channel of a running stream, or in a lake-like depression, or whether these deposits were formed from the "wash" of the ancient river now covered by the lava of Table Mountain, (which is probably the case,) cannot be ascertained without close observation and patientinvestigation. One of these patches, situated immediately to the east of the town, and about one hundred and eighty feet above the level of the basin, covers an area of about ten acres and proved exceedingly rich, most of the pay being found in a blue streak, varying from one to twenty inches in thickness and lying immediately above the bed-rock. The depth of the gravel in this tract did not exceed thirty feet, and the best surface-diggings of the vicinity were found on the slope to the east of this mound and in the bed of Wood's Creek. These detached masses of gravel are said to extend southerly into Mariposa County, where they exist in larger bodies, and will be worked immediately on the completion of several ditches now in process of construction. Toward the north we find the great surface deposits of the limestone belt which probably owe its origin to the

same causes.

The quartz ledges in the vicinity of the town are all supposed to be on the Mother lode, which lies immediately to the east. They are, beginning with the most southerly and proceeding north: The Clio, 10 stampsnot running for two years; Orcutt's mine (supposed to be on a spur of the Mother lode)-a very rich vein of decomposed quartz; Eagle, 10 stamps-operations suspended in mill pending completion of drain tunnel; the Shawmut-idle for two years; belongs to a Boston company and is closed on account of mismanagement and defective machinery.

Two miles northerly from Chinese Camp, and on the edge of the same basin, is situated the decayed and deserted town of Montezuma, which was once noted for its rich placers. Wood's Crossing, on Wood's Creek, one mile south of Jamestown, is noted as being the first ground worked in the southern mines, early in 1848. The creek here was very rich, and was worked by the Indians, of whom there were many here at that time. It is said that the first traders who came into this part of the country bought gold-dust from the Indians in exchange for its weight in beads, raisins, &c.

Jamestown.-Between Montezuma and Jamestown the country is broken up by rolling hills of no great elevation. The Mother lode is intersected and cut half a mile south of Jamestown by Wood's Creek, a stream carrying but little water in the summer, but very turbulent in the rainy season. At this point the croppings of the lode have a width of from twelve to sixteen feet, compact and boldly defined, with numerous spurs and parallel veins on the east side, but the quartz is barren at the surface. These parallel veins have proved very rich but not continuous. Abandoned excavations and tunnels show that they have been followed till they "pinched out" or became merged in the main lode. Near here, on the line of the Mother lode, are situated Quartz Mountain and Whisky Hill, famous for both rich quartz mines and great failures. The most noted mines are the Golden Rule, the App mine, the Heslep mine, and the property of Rosencrans, Preston & Co. on Whisky Hill.

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