Gravel deposits in the foothills.-The La Grange Ditch Company.—Extensive auriferous gravel-beds, apparently of secondary deposition, are found in the low rolling foot-hills of all the southern counties, but generally in localities remote from water, and in consequence their development has been retarded. During the past year thousands of acres of ground of this character have been purchased and located by San Francisco capitalists, and vast projects are under way for bringing water to them by tapping the rivers high up in the mountains. Of this character is the enterprise known as the "La Grange Ditch Company," which is one of many having like objects. This company own between four and five thousand feet frontage on the Tuolumne River, near the town of La Grange, Stanislaus County, formerly known as French Bar, their ground running back from the river a distance varying from one-half mile to one mile. The bed-rock lies at a sufficient height above the Tuolumne River to make a tunnel necessary for opening their ground. The gravel is soft and but little cemented and will wash easily. The banks (or gravelbeds) average about one hundred feet in thickness and prospects largely from top to bottom, several pan tests having shown the extraordinary average of three to five cents to the pan. The company are now building a ditch, taking the water out of the Tuolumne River, at a place known as Indian Bar, seventeen miles above their claims. This ditch is six feet wide on the bottom, eight feet on the top, and four feet deep, with a fall or grade of from six to ten feet per mile, and will carry four or five thousand inches of water, delivering it at a height of over two hundred feet above the level of the Tuolumne River. The ditch was commenced about the middle of July, 1871, and one thousand men have been constantly employed in its construction; eight hundred of these being Chinamen at one dollar per day, the white men of course receiving higher wages. The total cost of this ditch is estimated at $200,000, and it is expected to be complete in time for the company to avail themselves of the rise of the river early in 1872. Mr. Edmund Green, the superintendent, has adopted a novel method of taking the water from the river by which he avoids the risk incidental to a high dam. This is by digging a cut along the side of the river large enough to contain a box flume which will be covered with rock and dirt, leaving the bank of the river in its natural state. But little fluming will be used. Around rocky points a stone wall is commenced far enough down the banks to get a perfectly solid foundation. This is continued up to the top of the ditch and is made four or five feet in thickness, then an inner wall two feet wide and two feet distant from the outer one is built four feet high from the bottom of the ditch; clay is then tamped between these two walls so as to make it water-tight, the water running in the ditch inside both walls. They have in addition a winter ditch with a capacity of three thousand inches of water, taken from Dry Creek, three miles distant from the mines. The company will commence washing early in 1872 with five four-feet flumes, using four eight-inch nozzle improved hydraulic pipes under a pressure of one hundred and fifty feet. Should this enterprise prove a success, of which there is no reasonable doubt, capital will seek investment in like projects, and many thousands of acres of equally valuable ground will be developed in the southern mines.

Other gravel deposits.-Turner's and Kincaid Flat.-Many auriferous gravel deposits of great richness exist in various parts of the southern mines, particularly near the limestone belt, in basins or flats where, from the nature of the surrounding country, drainage is impossible except by the construction of long and expensive tunnels. These gravel-beds, like the detrital matter in the foot-hills, are probably the result of sec

ondary deposition in a recent geological epoch-the effects of the distribution by water of the ancient channels, and the denudation of the surrounding country. This theory is founded on the fact that in these basins the remains of the mastodon and elephant are found in great abundance, while in the old river-beds they are rarely discovered. These basins were worked in early times as deep as was possible by means of shafts, whims, and pumps, but as the bed-rock was approached the water was found to be an insurmountable obstacle, and they were temporarily abandoned. Subsequently, drain-tunnels of great length were run at various places where these basins occur. Two of these enterprises, the first in contemplation, the second nearly completed, will be briefly described here as an illustration of this branch of mining. The Turner's Flat and Table Mountain Mining Company early in 1870 acquired by purchase and location five hundred acres of ground at Turner's Flat, near Jamestown, Tuolumne County, this location giving them also 5,000 feet in length on the Table Mountain channel; the "flat" being on the eastern side of Table Mountain, and their location running down on the western side of the lava-covered mountain toward the Stanislaus River. They are now making application for a patent to this tract and negotiating for capital to open their ground. Turner's Flat is an extensive deposit of auriferous gravel, which has proved very rich, and is of unknown depth. Between the years 1853 and 1857, when in the possession of former owners, several shafts were sunk in the flat, near the line of the lava, to a depth of eighty feet, when a large quantity of water was encountered, of such volume as to resist the power of the best pumping machinery then in use. About the year 1855 or 1856, an English company acquired large interests on the flat, and endeavored to drain it by running a tunnel from Slate Gulch, a small stream tributary to Wood's Creek, lying far to the east of Table Mountain. This tunnel, if completed, would have been about three miles in length, but after spending $30,000 it was ascertained that an error had been made in the surveys, and the completion of the tunnel on the grade they were running would have brought them to the surface instead of the bottom of the basin, and the work was abandoned. No tunnel except one from Wood's Creek seemed feasible for the drainage of this ground, and this would have been nearly five miles in length with a light grade. This valuable property then remained unoccupied and undeveloped for a period of nearly ten years, when the present company acquired the ground and decided on a new point of attack by opening the bottom of Turner's Flat from the west side of Table Mountain, where the formation is very precipitous, instead of on the eastern side, where it slopes gently to Wood's Creek. This tunnel will enter the west side of Table Mountain about three hundred feet below its summit and about one hundred and fifty feet below the lava line. It is estimated from surveys that its total length will not exceed three thousand feet, and at that distance, with a grade of ten inches to twelve feet, it will tap the gravel deposits of Turner's Flat at a depth of one hundred and twenty feet. A deep gorge, setting back on the western face of Table Mountain, opposite the flat, greatly facilitates the construction of this tunnel. The Turner's Flat gravel deposit is evidently an outbreak from the Table Mountain channel, and had yielded about $1,000,000 before operations were suspended. The gravel on the bottom is said to have paid as high as $5 per bucket. The tunnel will be laid with flume, and the grade will be sufficient to effectually break up the gravel and release the gold.

The Kincaid Flat Mining Company is a San Francisco company, who have been engaged for several years in an enterprise similar to the

above, and are now approaching its completion. Kincaid Flat is a basin-like depression, surrounded by low hills, situated a few miles from Jamestown, Tuolumne County, on the eastern verge of the great limestone belt, and contains about one hundred and fifty acres of gravel of unknown depth. Mining was commenced here shortly after the discovery of the placers on the limestone belt, and immense sums were taken from the flat. Rumor says that one claim fifty-five feet square yielded $100,000, and that the total product of the flat was not much less than $2,000,000. While any estimate of the yield of a tract of mining ground in early times must be accepted with due allowance for local exaggeration, it is undoubtedly true that this ground was notoriously and fabulously rich. The present company having acquired this ground several years since, commenced a tunnel from Sullivan's Creek, the nearest depression, and · have been working on it ever since. After running an open cut two hundred and fifty feet, they commenced a tunnel, and had run one thousand three hundred and thirty-five feet up to November, 1871. They had four hundred feet more to run to strike the bed-rock of the basin. Their tunnel is about five by seven, and for one thousand three hundred feet runs through limestone, when they encounteret a trap-dike of excessive hardness, which will materially delay its completion. The tunnel has already cost $60,000, and is in all respects a model piece of work. The labor has so far been done by hand, but it is probable it will be completed by machinery. This tunnel will not drain the flat below a depth of eighty 40 feet from surface. The construction of such an expensive work shows the confidence of our local capitalists in the undeveloped resources of our mines.

3

Black lava.

Gravel.

30 Light lava.

5 Gravel.

At Mokelumne Hill, Calaveras County, extensive operations are carried on in the ancient channels, which are not yet exhausted. They will be noticed at some length in this report. Near San Andreas, Calaveras County, and in the vicinity of Angel's, Murphy's, and Vallecito channels, mining will be prosecuted with vigor during the coming year. At Byrnes' Ferry a New York Company have tunneled Table Mountain and are said to be taking out good 15 Light lava. pay. Extensive gravel operations are also in progress at Garrote, in Tuolumne County, and in various parts of Mariposa County. There is much similarity in methods of mining in these various .localities, and my time and space will not admit of more than general descriptions of some of the representative claims, selected on account of the magnitude of their operations. These will be found scattered throughout this article.

25

9

5

4

Gravel.

Dark brown lava.

Gravel.

Red lava.

17 Gravel.

The formation of gravel deposits.-As frequent mention has been made of gravel operations in isolated patches which were formerly parts of ancient riverbeds, I present the section of a shaft in a claim near Angel's Camp, Calaveras County, in which a human skull was found at a depth of one hundred and thirty-two feet, imbedded in a stratum of gravel five feet in thickness. The figures on the left-hand side represent feet, and show the thickness of the different 153 strata. The skull was found in the five-foot gravel-bed above the "red lava."

Slate.

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.