USA > California > Nevada County > History of Nevada County, California; with illustrations descriptive of its scenery, residences, public buildings, fine blocks, and manufactories > Part 44
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with theni in a day ; and after the water and dirt have run over them for an hour, they are fastened very tightly by the sand collected between them. In large sluiees, wooden riffle- bars are worn away very rapidly -- the expense amounting sometimes, in very large and long sluices, to twenty or thirty dollars a day ; and in this point there is an important saving by using the stone bottoms. They are used only in large sluices and they generally have a grade of twelve or fourteen inches to the box of twelve feet.
Flumes are usually made with boards, an inch and a half thick for the bottom, and an inch and a quarter thick for the sides. At intervals of two and a half feet there is a support. for the flume-box, consisting of a sill, posts and cap. The sills are four inches square ; the posts three by four inches, and the caps one and a half by four inches. To crect a flume 25 fect high, costs about twice as much as to lay one on the level of the ground, and at 60 feet it costs about four times as much. The annual repair of a flume is about one-eighth of its original cost, in favorable circumstances. If the flume is left dry several months, the repairs may be more, for the sun warps and splits the boards and draws the nails. A flume box, 40 inches wide by 20 inches decp, with a grade of 13 feet to the mile will carry about 800 inches, and such a flume built on the surface of the ground will cost now at the rate of $4,000 per mile, near a saw-mill. The boards are put in the flume rough, but are always battened, and sometimes caulked. The cheapest flume costs twice as much as the cheapest ditch of the same capacity, and the repairs of a flume cost 90 per eent. more than those of a ditch. The duration of a high flume is on an average about six years, and of a low one eight or ten. The flumes in the highest portions of the Sierra are troubled by the snow, and much labor is spent on them every winter. The weight of the snow is so great that after every snow storm, or while it is in progress, a man must go along and clear the flume with a shovel. In cases where the flume is on a hill-side, it is necessary to shovel away the snow from the upper side of the flume, for the mass moves. down hill with tremendous weight, though with very slow motion, and no flume could resist it.
The rocker or cradle bears some resemblance in shape and size to a child's cradle, and rests upon similar rockers. The eradle-box is about forty inches long, twenty wide, and four high, and it stands with the upper end about two feet higher than the lower end, which is open so that the tailings ean run out. On the upper end of the cradle-box stands a hopper or riddle-box, twenty inches square, with sides four iuches high. The bottom of this riddle-box is of sheet-iron, perforated with holes half an inch in diameter. The riddle-box is not nailed to the craclle-box, but can be lifted off without difficulty. Under the riddle is an "apron " of wood or cloth, fastened to the sides of the cradle-box and sloping dowu to the upper end of it.
Across the bottom of the eradle-box are two rithle-bars about an ineh square, one in the middle, the other at the end of the box. The dirt is shoveled into the hopper, the "eradler " sits down beside his machine and while with one hand with a ladle he pours water from a pool at his side upon the dirt, with the other he rocks the cradle. With the water and the motion the dirt is dissolved, aud carried down through the riddle, falling upon the apron, which carries it to the head of the cradle-box, whence it runs downward and out, leaving its gold, black sand. and heavier particles of sand and gravel behind the riffle-bars. The long tom is an improvement upon the rocker and of supe- rior capacity.
The pan is used in all branches of gold mining, either as an instrument for washing or as a receptacle for gold, amalgam or rich dirt. It is made of stiff tin or sheet iron, with a flat bot- tom about a foot across, and with sides six inches high, rising at an angle of forty-five degrees. A little variation in the size or shape of the pan will not injure its value for washing. Sheet-iron is preferable to tin, because it is usually stronger and does not amalgamate with mercury. The pan is the simplest of all instruments used for washing anriferous dirt. Some dirt, not enough to fill it full, is put in, and the pan is then put under water. The earthy part of the dirt is rapidly dissolved by the water, assisted by the shaking of the pan and the rolling of the gravel from side to side, and forms a mud, which iuns out while clean water runs in. The light sand flows out with the thin inud, while the lumps of tough clay and the large stones remain. The stones collect on the top of the clay, and they are seraped together with the fingers and thrown out. This process continues, the pan being gradually raised in the water, and its outer edge depressed, until all the earthy matter has been dissolved, and that as well as the stones swept away by the water, while the gold remains at the bottom. Panning is not difficult, but it r quires praetiee to learn the degree of shak- ing which dissolves the dirt and throws out the stones most rap- idly without losing the gold. Amalgam ean be separated from dirt, by was'ing, almost as well as gold. In panning-out it frequently happens that considerable amounts of black sand containing fine particles of gold are obtained, and this sand is so heavy that it cannot be separated from the gold by washing. while it is easily separated in that way fromn gravel, stones, and common dirt. The black sand is dried, and a small quantity of it placed in a " blower," a shallow tin dish open at one end. The ininer then, holding the pan with the open end from hint!, blows out the sand, leaving the particles of gold. He must blow gently, just strong enough to blow out the sand, and no stronger. From time to time he must shake the blower so as to change the position of the par- ticles, and bring all the sand in the range of his breath. The gold cannot be cleansed perfectly in this manner, but the sand
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HISTORY OF NEVADA COUNTY, CALIFORNIA,
contains iron, aud the little of it remaining is easily removed by a magnet. The blower should be very smooth, and made | sponge-cake in appearance.
of either tin, brass, or copper.
The puddling-box is a rough wooden box, about a foot deep and six feet square, and is used for dissolving very tough elay. The elay is thrown into the box, with water, and a miner stirs the stuff with a hoe until the clay is all thoroughly dissolved, when he takes a plug from an augur hole about four inches from the bottom, and lets the thin solution of the clay run off, while the heavier material, including the gold, remains at the bottom. He then puts in the plug again, fills up the box with water, throws in more clay, and repeats the process again and again until night, when he cleans up with a cradle or pan. The puddling-box is used in very few places in California.
Dry washing is a method of winnowing gold from dirt. In many parts of the mining districts of California, water cannot be obtained during the summer for mining purposes. The miner therefore manages to wash his dirt without water. He takes only rich dirt, and putting it on a rawhide, he pulverizes all the lumps aud picks out the large stones. He then with a large, flat basin throws the dirt up into the air, catches it as it | comes down, throws it up again, and repeats this operation un- til nothing but the gold remains.
The separation of the gold, amalgam and quicksilver, from the dirt in the bottom of the sluice, is called " cleaning up "; and the period between one " cleaning up " and another is called a " run." A run in a common board-sluice usually lasts from six to ten days ; in a large hydraulie claim, one month, Ordi- marily the sluice runs only during daylight, but in hydraulic claims the work continues night and day. Cleaning up oceu- pies from half a day to three days, and therefore must not be repeated very often, because it consumes much time. In some
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1 sluices the cleaning up does not occur until the bed of the sluice has been worn out or much bruised by the wear of the stoues anl gravel. Cleaning up in small sluices is considered light and pleasant work, and is often reserved for Sunday. At the time fixed the throwing iu of dirt eeases, the water runs until it becomes clear, the false bottom of the sluice is taken up in sections, and the heavy sand, amalgam, and quicksilver, taken up in pans. After separating the sand, the quieksilver and am- algam from the sluice are put into a buckskin cloth, and pressed so that the liquid metal passes through, and the amalgam is re- tained. The amalgam is then heated, to drive off the inereury. This may be done either in an open pan or in a close retort. In the former the quicksilver is lost ; in the latter it is saved. The pan is generally preferred. Often a shovel or plate of iron is used Three pounds of amalgam, from which the liquid metal has been carefully pressed out, will yield one pound of gold. The goldl remaining after the quicksilver has been driven off by
heat from the amalgam, is a porous mass, somewhat resembling
ANCIENT RIVER CHANNELS.
Before describing the methods of mining employed on the immense gravel deposits that form the beds of extinct rivers, it is proper that a description of these gravel deposits be given.
The prevailing rock is granite and metamorphic slate, overlaid in many places by vast flows of lava and volcanic material. The gravel deposits, where covered with lava-flows, lie sometimes several hundred feet below the erest of the hills. The nature and mode of formation of these gravel beds is now pretty thoroughly understood, and it is the accepted theory that the high gravel deposits of the western slope of the Sierra, mark the course aud occupy the channels and furrows of ancient rivers, which, with their tributary streams and ravines, once . formed the drainage system of the country. That system, uo doubt, resembled the present in many respects; its rivers were large, and flowed sometimes in deep, narrow gorges, with precipitous sides and steeply descending grades; in places the streams must have occupied broad cañons with gentle grades, sometimes expanding into little lakes.
It is the opiuiou of geologists, that subsequent to the tertiary period was the time when the main valleys of the continent were excavated by erosion. It was probably in this epoch that the deep-lying auriferous gravel was produced from the degra- dation of the metamorphie schists and quartz veins of the Sierra, by the joint action of water and glaciers. By the detritus formed in this mauner (by a process elosely analogous to the filling of the present river channels by debris from the hydraulie mines), the troughs of the streams were filled to overflowing with immense deposits of gravel, that were brought down by floods from the higher country. This filled up the river beds aud compelled the water to scek other chaunels, resulting iu our present system of drainage, In the meantime the gravel flood was succeeded by volcanic activity, during which great volumes of lava and voleanie matter poured down the mountains, following and covering the gravel deposits, sometimes to a great depth, forming the great sheets of volcanic material that now cover so much of the gravel ranges.
Working upon this material, modern erosion has earved out the present surface of the eouutry, with its much deeper river i beds and system of tributary canons, reviues and gulches. The general level of the water chaunels of the present drainage system is so much lower than the oldl, that where was formerly the bed of the river, is now, in some places, the dividing ridge between two streams. From the mass of detritus that was deposited in the ancient channels, lave sinee been carved and mouldled the gently sloping hills that now form, in part, the crests of the ridges. The bodies of lava that were once depos-
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ited on the gravel have, in some places, been again removed, exposing the gravel that it covered. The gravel, also, ha- suffered much erosion, and in places has been partly or wholly washed away, so that what was once a compact body of approx- imately uniforin depth, is now an uneven mass, forming rauge; of hills hundreds of feet high and separated by deep ravines. Where the process of denudation has been less active, the lava still lies in heavy bodies, covering the gravel channel, in places, several hundred feet deep.
The material deposited in these ancient channels is generally composed of rounded and water -worn masses of quartz, slate, granite and all the rocks of the Sierra, varying in size fromn h'ige bowlders of many tons to small pebbles and fine sand, accom- panied by occasional beds of a very tenacions clay. Quantities of lignite, or fossil wood, little changed from its original con l :- tion, but blackened to the color of coal and flat with prasur, are frequently found. Among these remains are logs similar in appearance to the manzanita now growing in abundance on t' e hills, some of which have measured eighteen inches in diameter and fifteen feet in length. Occasionally the mass of ancient drift-wood accumulated in the eddies of the current, where they were deposited with the fine sands, amount almost to a continuous bed of lignite. The higher portions of the deposit commonly called " top gravel," forin a not very compact mas-, sometimes white, but generally of a yellowish or reddis! brown color, due to the oxidation of iron. The lower portions. in which the process of oxidation has been complete, have a blue or green tint. The bottom gravel is generally a very compaet conglomerate and firmly cemented together by iren pyrites, so that the force of gun powder is required to break it up. This has been denominated cement by the miners, an.l is often crushed in mills after the manner of quartz. A few months' exposure of this eemuent to the atmosphere produce a disintegration, due to the decomposition of the associated 1 STite- that held it together. These masses are sometiutes left expos ! to the action of the el_ments a whole season, to secure the benefits of the consequent disintegration.
As has been remarked, the deposits were partly formedl ly detritus from the degradation of quartz veins, and the result is that the whole mass is, to an extent, auriferous. The go l ts not to be found in large masses, but is disseminated iu s1 all quantities throughout the entire deposit: nor is it evenly dis- tributed. The upper, or top gravel. is of less value than tist which lies below, and though poor. is inoure uniform in tl . As- tribution of gold. This is sometimes so por that it would be unprofitable to work it alone, but as by the hydraulics it is necessary to remove this in order to read's the rich de was below, it is all washed away, generally yielding enough to pay the expenses of the operation. The richest deposito lie walu a few feet of the bed rock, and although following the griend
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HISTORY OF NEVADA COUNTY, CALIFORNIA.
course of the stream, lie in streaks whose courses change with the capricious changes of the currents in the channels where they were deposited. The bottom gravel varies exceedingly in richness, according to the nature of the current, its swiftness or «luggisbness, eddies, obstructions, etc., showing the same phenom- ena of seant and rich deposits observed by the miners of the early days along the streams of our modern drainage system.
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The exact course and direction taken by these extinet rivers is yet, to a large degree, a matter of speculation and theory. Their channels have been opened in hundreds of places, but in most instances not sufficiently to determine which channels are connected with others, and which are distinet and separate. It has been pretty well determined, however, that the general course of the streams is almost at right angles with the present rivers that carry the water of the mountains into the valley, or, iu other words, nearly parallel to the general course of the great Sacramento river. The first appearance of the ancient channel in Nevada county is at Snow Tent, in Eureka town- ship, where it has crossed the Middle Yuba river from points above in Sierra county. From here its course is southwesterly through Orleans Flat, Moore's Flat and Woolsey's Flat to North Bloomfield, where an evidently tribnary stream joins it from Relief Hill, and, probably, from points in Washington town- ship. Its course is then to the west to near Columbia Hill, and just before reaching this point receives another tributary from the direction of Grizzly Ilill. From Columbia Hill it con- tinues its westerly course to Cherokee, where it turns abruptly to the north until it reaches the Middle Yuba at Badger Hill. It then apparently follows the same channel now used by the river to a little distance above North San Juan, when it turns to the southwest, passing through Sweetland and Birchville to French Corral. At this point all trace of it is lost until it reap- pears at Mooney Flat, Sinartsville and Timbuetoo, to be lost in the hills receding into the valley. The channel thus described is the one being worked on the ridge between the Middle and South Yuba rivers.
At Blue Tent, just south of the South Yuba, a channel has been opened, but whether distinct or a portion of the ridge channel is a question not yet fully determined. From Blue Tent this channel continues south through Scott's Flat, Quaker Hill, Hunt's Hill, You Bet and Little York to Dutch Flat, and is believed to continue south through Placer and into El Dorado county. The direction of the channel above Nevada City, where the ancient gravel deposits were first discovered and worked by the " coyote " process of mining on old Coyote Hill, is not certain, but it is supposed to be a portion of this grand channel just described. A branch seems to run from near Quaker Hill in a westerly course, south of and parallel to Decr creek, passing south of Nevada City, and north of Grass Val- ley and Rough and Ready, at which point all trace is lost, but
supposed to continue its course until it joins the ridge channel first described, at Mooney Flat.
Lying between Bear river and Greenhorn ereek is another channel commeneing far up the mountains in Washington township, but which has not been opened to any extent higher up than Remington Hill and Lowell Hill. This channel erosses Bear river at right angles near Liberty Hill, and also runs southwesterly north of Bear river to Chalk Bluff, joining the great channel running south. To which 'channel the gravel beds of Omega, Alpha and Gold Hill belong is still a question of doubt. They may trend off southwesterly and join the channel last described, or, what is more probable, may tend northwesterly and unite with the ridge channel at North Bloom- field, passing through Relief Hill.
In future years, when the beds of these extinet rivers shall bave been laid bare for miles by the sure agencies now being employed npon them, it will be possible to determine the exact course of tbe channels, their tributarics and feeders, but in the light of present developments a positive statement cannot be made. Future developments may reveal channels that are yet unkuown, and demonstrate the existence of both large and small streams that will change materially the theories at pres- ent held as to the course and dircetion of these long extinet rivers.
An excellent map has recently been prepared by P. Huerne, C. E., by which the probable course of these ancient streams can be clearly traced, the claims of the various mining companies being marked upon the map in colors. This map was used by the Comunittee on Mining Debris iu their recent report to the Legislature.
HYDRAULIC MINING.
Briefly defined, hydraulic mining consists in washing down the auriferous hills of the gravel range by directing a powerful stream of water against the bank, the dirt and rocks being carried by the water through a sleep eut or tunuel, in which is set a system of flumes or sluices for catching the gold, being finally discharged into some ravine or cañon and denominated " tailings."
Ground shuiicing came into general use on the "coyote " range, near Nevada City, in 1831-2, and while working by this method, A. Chabot introduced some thirty-five or forty feet of hose into his claim on Buckeye Hill, the water being conducted from the bank to the bottom of his diggings in a wooden box, strengthened by iron clamps, so as to withstand a pressure of 'sixty feet. This was in April, 1852, and the hose was found to be very convenient in sluicing off the dirt after it was picked down from the bank. There was no nozzle attached to it, and it does not appear that the idea that anything could be accom- plished by directing a stream of water from it upon the bank
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ever occurred to Mr. Chabot. This idea lay dormant for a year, but in April, 1853, E. E. Matteson, who was working with his partners in a elaim on American Hill, conceived the idea of facilitating the labor of breaking up the bank by directing a stream of water against it. He attached a nozzle to a piece of hose, and bringing the stream to bear upon the bank, discovered that the small stream of water could accomplish the work of a great many men. The advantage of this method was so obvions that it was soon introduced into all claims so situated as to render it available.
Great improvements have been made in the method of hydraulie mining. The first hose used had but a half-inch nozzle, and was made of canvas. This was gradually increased to two-inch nozzle, still using canvas hose. For the hose, pipes of boiler iron, generally of eighteen inebes in diameter, are now used to conduct the water into the elaims, sometimes from a hight of four bundred feet above the point of delivery, giving a terrific pressure at the point where the stream is turned upon the bank. These iron pipes are ribbed and inade of great strength to resist the enormous strain upon them by the out- ward pressure of the water. For the hose with the nozzle at tbe point of delivery bas been substituted an iron machine, so constructed as to be readily mnoved from side to side, depressed or elevated by the pipe-man, who is thus enabled to direct the stream at any desired portion of the bank with great facility. The orifice of the pipe, from which the water is discharged, is generally seven inches in diameter, altbough a great inany are as large as nine inebes. The force of the stream produced by the downward pressure of water at an elevation of three hundred feet is difficult to be realized or described. The torrent of water rushes out from the pipe with an angry roar and hurls itself in an unbroken mass two hundred feet. The bank crumbles before its might, and the dirt and rocks are washed swiftly away to the mouth of the tunnel, through which they are carried by the muddy stream. A large stone of fifty pounds weight, tossed npon the stream as it issnes from the mouth of the pipe, will be carried with the speed of an arrow a distance of a hundred feet before it recovers from its astonisment enough to roll off. Should a man seat himself astride the rushing column of water, it would carry him at least a hundred feet before his weight would be sufficient to allow him to drop through to the ground .A dis- ellarge of 1,000 inches of water in a single stream is not unusual; such a stream would discharge 1,570 cubic feet per minute, or in a ten hours' run the enormous total of 942.000 cubic feet, equal to 7,085,000 gallons of water. The amount of earth that can be washed away by this volume of water is enormous. Various estimates have been made of the relative amount of water used to earth washed away, and the accepted proportion is seven cubic yards to one inch running twenty -
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HISTORY OF NEVADA COUNTY, CALIFORNIA.
four hours. This of course is greater or less un proportion to the nature of the ground being worked. At that rate a run of ten hours would wash four aud one-half cubie yards, or the quantity of water above given would excavate 2,833 cubic yards of carth.
It is obvious that one of the essential conditions in this method of mining is that of a suitable outlet from the elaim, for the discharge of the body of water thus employed, and for the disposal of the material removed by it, and, especially, of a sufficient grade for the proper establishment of sluice boxes and other gold saving appliances, through which the stream must pass, carrying along with it the mass of auriferous debris. The sluiees for this purpose are always many hundred and frequently thousands of feet in length. Their grade must be enough to give the water sufficient velocity to carry through them the mass of gravel and rocks washed down from the banks, The grades employed are usually from 6 inches in 14 feet, or 3} per cent., to 10} inehes in 12 feet, or 7} per cent., and even greater. The former is considered a very light grade, but lighter ones are sometimes employed where the conditions of the surface leave no roomu for choice.
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