GIGANTIC MINING OPERATIONS.

Grey River Argus, Volume XII, Issue 1101, 7 February 1872, Page 2

GIGANTIC MINING OPERATIONS.

[SAN .FRANCISCO NEWS LETTER.] It is well known to our California' I ' readers that the gravel channels which intersect the western slope of the Sierra, Nevada Mountains are one of the inogi -, prolific sources frojn. which <mt gaH"& ' derived. Perhaps the most: important of idPthe ';■': > •gravel deposits known in bur State exists 'in that section of it lying in? Nevada "i County, between the South and Middle Forks of theYiiba River. This channel' (as it is called, and perhaps properly named, of an old river) has been worked wherever it could be reaohed and- water could be had, for over twenty yeata at very many places, and many millions of f "gold have been taken fromifc' .: itsvexist-JL" ence has been known since California was settled, and it is traced plainly from Snow ~ ,' Point on the Middle Yiiba in atifun- f //. broken channel to French Corral, . a di? ? / tance of two miles. '- : . ": In connection with' this channel, which is worked entirely by what is known as the hydraulic: process; .":.; innumerable tunnels have been run— taking,years to construct, and large and . expensive works have been constructed to t supply water. One company alone, the I Eureka Canal Company, at present owns ; some two hundred miles of ditches and canals. Their main canal or ditch alone, from their reservoir near, the summit of the Sierra Nevada Mountains to -San.: r : Juan, is sixty miles in length, and the total amount expended upon: their workaf ?• has not been less than 2,000,000d015. Their supply of water is not adequate to the demand, and the only difficulty which ''? will exist in the future in order to develop.;., the mining interests upon this channel w vfche supply of \yater. ' - '; Water in abundance is the great des- > ideratum in hydraulic mining, and asj new inventions and appliances have been* brought to bear, mining claims have become consolidated into large and strong corporations, until now a mining: claim. *• ■ which does not consume 800 to JOOO inches of water (or- say twentyVinlUion gallons a-day) is considered a rather small affair. - :•>■■■;■ . _■; • . •■..-. .-. • , ■.-■•:.■)•■ The immense gravel channel or deposit - n is of a depth varying from 200 to 4oo feet/ 1 r and perhaps is even deeper in some places. The top portion of it for, say half of its v; depth (or more at its greatest tMcfcness),' consists of white gravel— spike clay; -.<.> whereas, its lower, portion, for say "froto ' 30to 150 feet in depth, consists of blue gravel. In some portions of the channel the blue gravel is cemented or conglomerated, and has to be blasted before it can be mined out by water, "and in some places, where the bottom of the channel (or bed-rock) has been exposed/ it is ■■■ crushed in mills. : >: - The largest and by far the most import: ant graver mines upon this channel; or perhaps in the world, is the, mine or claim 4 owned and worked by the N^rth Bloom- . field Grave} Mining Company. This c0m,? . : ., pahy, consisting of sotne of our ;tao*t prominent and wealthy citiaens, has a Share capital of 40,000 shares, of the par ■ value of lOOdol. The company own, about 1600 acres of this gravel channel," v ~ and from shafts which have been sunk to the bed rook of the channel at various points, they know that they have undeiv ?- lying the top or white gravel, a deposit " 135 feet in depth of blue gravel, which is entirely free from cement or pipe day. The width of thin channel at the bottom is not yet determined, although drifts have been run from the bottom of the shafts, on bed-rock; across the channel

has been found. From the fact that the bed-rock is falling, in direction of drift across the channel, it is knbwn thai the deepest part of the channel has not yet been reached, and it is now believed that the ohannel is over 2000 ft in width at the bottom. The company, after securing their claim by purchasing small claims and consolidating them, became satisfied of their ultimate value, and three years ago turned their attention to bringing water to them. In order to accomplish this, they constructed large reservoirs in canyons of the Middle Yuba and Canal Creek (a tributary of the South Yuba), having a strong capacity to the extent of the utmost wants of their mining operation?, and constructed a canal 40 miles long from Canal Creek Reservoir to their works, completing them last fall. This canal has a capacity of 60,000,000 gallons of water a day. They have yet to construct a canal some thhteen miles only, to reach their reservoir on Middle Yank, which is the largest reservoir in the state. When this canal is constructed, the company will have a perpetual supply of water equal to nearly 100,000,000 gallons a day. By the time their system of water works is completed they will cost about 760,000 dols. The company have been five years in aggregating their claims and constructing canals and preliminary works, and up to this time have expended about one million dollars. They are now engaged in stripping or mining off the top or white graval and pipe day to a depth varying from 50 to 160 feet, and are employing for this purpose alone about 3000 inches of water a , day, or about 60,000,000 gallons per twenty-four hours. The top or white gravel carries but little gold, and averages about two to two and a quarter cents per ton only. Yet even with, this low value it pays the company well, as the cost of .running is very light, not exceeding some 8000dols. per month, including the cost of running water. The cost of pipes conveying water to the works, including nozzles and fixtures, has been Borne 60,000d015, and their mining flames, alone of which they have in all about 8000 feet in length, have cost them about the same amount. They use their water under a pressure or head of about 300 feet, discharged against the gravel bank through nozzles six inches in diameter, each nozzle requiring about 100 inches of water to supply it,«or about twenty million gallons a day. of^twenty-f our hours. The company, for the past six months, have also been engaged in sinking shafts from the level of their present works down to the bed rock, or bottom of channel, and have three of them at work, and are now starting work upon the fourth one. The extreme length of the ground owned by the company is about two miles or more, and their mining operations in top gravel extend now about 3000 feet in width across the course of the channel, and drifts from the same which have been ran.. The shafts which have been sunk by the company have developed a body of blue gravel underlying the white gravel, and extending down to the bed rock of the channel, 136 to 160 feet in depth. The blue gravel is of exceeding richness, and contains gold varying from one dollar to twenty dollars per ton of gravel. {n order to reach and work this rich and extensive deposit, a tunnel has to be constructed from the South Yuba River 1600 yards in length, and the surveys for the same are now being made, it being th»intention of the company to drive it forward as vigorously as possible. The past operations of the company lead them to know that when all their works are completed and in operation, they can mine easily 100,000 tons of gravel a day. For mining this enormous amount daily, it will take seventy-five years to exhaust their ground alone, which is but a small portion of this immense grand channel. This company have gone forward steadily for the past five years ; have expended vast amounts of money in their works, and propose ip expend much more. That the reward will be great no one can doubt* t . A visit to the mines of this company, even at the present time, will well repay any one who has leisure and inclination, as it takes but a pleasant day's travel to reach Nevada Oity, and from there a beautiful drive of three hours' places the visitor at the mines. In order to see the large and expensive works connected with the wator supply, a person must be a good pedestrian, and have a dear head, as there are some places where it makes one giddy to look down from the flume upon which he tatut walk. But with good walking proclivities, and a head which does not get giddy in high places, a pedestrian trip from the Canal Creek reservoir, along the canal, to Bloomfield, forty miles, will repay any one, as the tfenery cannot be excelled, and the works of the company are also well worth seeing.