Volume 35 (1877) (426 pages)

October 13, 1877.] MINING AND SCIENTIFIC PRESS 233 Hydraulic Mining in California.* {By Avo, J. Bowls, Jr, A. B., Mlalng Engineer } Brief Outline of the General Topography of the Gold Regions of California. The topographical features of Califernia, as demenstrated by the explorations of the State Geological Survey, are found to be exceedingly simple, Tiree equidistaut parallel lines can be used in conveyiug a general idea of the physical geography of eentral California. A straight or “ain axial line,” whose ceurse would be north 31° west, (passing through the culminating peaks of the Sierras for a distance of 500 miles, can be assumed as the western boundary of the State. A second parallel drawn 55 niles weat ef the '‘niain axial line” will skirt the western base of the Sierra Nevada, along the edge of the foot-hills. A third parallel run equidistant from the second will represeut, ‘tas nearly ax possible, the western base of the Coast ranges,” ‘These pera iets divide the Stato into three belts, namoly, the Sierra, the great Valley ef California, and tho Coast ranges. “This arrangement of the physical features holds good for a length of 400 miles in the direction of the main axial line, comprising almost the whole of the agricultural aud the greater part of the miuing districts. "+ The section of the country which is of immediate interest to the miner ia the westcrn slope ef the Sierras. ‘These mountains, rising in a short distance {yom the Sacramento plains to elevations of ever 7,000 fect, with occasional peaks 10,000 and 12,000 fect high, are cut by numerous decp aud precipitous gorges or canyona, through which drains the inunense watcrshed of the Sierras, supplying the main rivers of the State, and ultimately emptying into the Pacitic ocean. Between these canyons, ridges or divides are formed, on top of which gold placcrs are found. These gold-bearing surface. deposits extend from Shasta in the uorth to Kern county in the soutb, the most extensive deposits occurring in Plumas, Sierra, Placer and Nevada counties. The term shallow placers is applied to deposits of gravel and earth whose thickness varies from a few inches to five or six feet in depth, to distinguish them from deep placers or detrital accumulations found in ancient channels covering large areas, and varying from 100 to several hundred feet in depth. The Discovery of the Gravel Deposits Containing the Precions Metal. The pionecr miner, after working out the river hars, followed up the stream to find ‘‘the source of the gold.” Its existence was discoyercd from slides, denudations, and hreaks in channels, which subsequent explorations proved to be tbe ancient river system of the State, whose general course is nearly at right angles to the present river system of California. The indefatigahle prospector, advancing further into the unexplored niountains, again discovered gravel heds at elevations of scveral thousand feet ahove the present water-level. The streams flowing through the precipitous canyons of the high Sierras aided materially in the development and discovery of the gold fields, Their watera were soon appropriated for gold washing, and thus was inaugurated the system of mining ditches, which to-day extends over several thousand miles, The immense gold-hearing drift inclosed hetween channel walls, or ‘‘rim rock,” as it is called, was explored hy means of tunnels driveu in from bordering canyons, tapping the bottom of the deposit, enahling the extraction of the pay stratum, which was suhsequently sluiced to extract the gold. This style of mining received the name of ‘‘deep placer mining "= Little hy little the “‘top dirt” of these deposits, composed chiefly of light soil, clay, fine gravel, and streaks of sand, was washed off, andin places considerahle gold was thus ohtained. Canvas hose was hrought into use to convey the water over the hanks for washing the dirt, and from this originated hydraulic mining. In the progress of the work strata were found composed of houlders, pehhles, quartz, saud, and various rocks cemented togetber, requiring the use of powder to hreak them up. The color of this cement was in places white or reddish, and sometimes hlue. Shafts sunk in these strata discovered the presence of gold in great ahundance, and a fresh enthusiasm was thus infused into grave] mining, already on the wane, as the river hars were becoming exhausted. The Gold Bearing Deposits of California. The auriferous deposits of California are ehietly contined to the western slope of the Sierra Nevada mountains. The principal counties in which placer mining is carried on are: Shasta, Trinity, Plumas, Sierra, portions of the cast side of Butte and Yuba counties, also Nevada, Placer, KE] Dorado, Amador, Calaveras, Tuolumne, Mariposa, and Stanislaus counties. ‘It ishcre,” says Professor Whitney, ‘‘that the helt of metamorphie slates and sandstones, which is peculiarly the gold hearing formation of the State, is developed to its greatest width, and least concealed from the miners’ explorations by the ~ A paper read before tbe American Institute of Mining Engineers, at the Wilkes-Barre meeting, May, 1877. t+ See vol. i. p.5, Geological Survey of Califurnia, J. D, Whitney, State Geologist. { Deep placer mining is now carried on in those sections of tho State where the rie: deposits are covered witb thick beds of lava, rendering hydraulic mining impracticable. presence of nverlying non-metalliferons formatiens. It ie here that the physical conditions have most favored the concentration of the geld in the detrital formatien, so that it conld be ohtained by simple washing, without the necessity ef mining for it in the selid rock, and perhaps mere réadily aud mere abundantly than any regien ever opened to seckers after the precious metal?’* The yold deposits are found in river channels, in hasina and en flats, alse as isolated rolling hills, and occur either as accumulations of gravel alene, restiug dircetly en the surface, or as accumnilations of detritus, consiating ef gravel, sand, drift, pebhlcs, and boulders of all sizes covered with lees and other volcauic products. Their geolegical ages are Post-Tertiary and Tertiary. Quantities of fossil wood and numerona remains of land and water animals have heen Color found in most every pan in this top gravel. } Good gravel. ‘\ Bluo gravel from top down for 50 feet, Averaged about 10 eolors to the pan. /. Streaks of clay throngh gravel, thiekest 8 inehes. Gold very fivo until green gravel was struck. Here soft and sandy. . Mueh quartz. Pipe elay disappeared. Tere appeared a little eement, Gravel coarser, some eement. Gold eoarser since striking green gravel. Here mueh eement. 180 190 Thin strata of sand. Last 8 ft. 5 to 20 cts, to pan Cement. Figures within the shaft indicate the nuniher of colors to the pan, every test made fron: 120 foet down ia here recorded, Sketch of Shaft No. 1—Malakoff—North Bloomfield Gravel Mining Company. found in the deposits, and are being constantly unearthed as the mines are worked. The auriferous alluvions mark the lines of ancient rivers, whose action on a grand scale was analogous to that which can he daily seen along the streams which receive the tailings from the hydraulic claims now being worked. Voleanie eruptions have iu places covered these deposits with lava and tufa, hundreds of feet deep. Denudatiou and erosion, the companions of ‘lime, have subsequently played their parts, and later in turn the product of volcanic activity has heen overlain with gold bearing detritus. These gravel channels are from a few hundred to several thousand feet wide, and range from the shallow placer to a drift 600 or 700 feet in depth. Their richness in gold varies in general, as well asin particular, in the many parts of the State. Ferruginous-colored spots, so well marked in ‘tupper or top gravel,” are not always as pro* Geological Survey of California, vol. i p, 214, J, D. Whitney. ductive in gold here as they are generally found to be in the gold alluvia of the Ural mountains. A black saud, cemposed chictly of glancing grains of magnetic iron, generally accompanies the precious metal, thongh it dovs net indicate its presence. Dr. 'T. Sterry Hunt, speaking of the erroncous impressions which prevail in refereuce te the presence of black sand in anrifcrons alluvions, very appropriately remarks that “similar black sand residues, eousisting chietly of various ures of iron (sometimes oxide of tin and other minerals), may he obtained from the washing of aliuost all sands and gravels derived from crystalline rocks, and that the occurrence of a black saud, therefor, in uo way indicates the presence of gold. When, hewever, this metal is present ina gravel, it, from its great weight, remains behind with the black sand and dense matters in the residue after washing.”* The Distribution of Gold in Gravel Deposits. It is not unfrequeutly stated that it is from the washing of the entire hanks that the gold is to be expected, it being disseminated throughout the whole deposit. That deposits are or are not auriferous for their cntire depth will not be discussed; but that gold is proportionately diffused throughout tho detritus, so that it could all he considered as ‘‘pay,” is denied by experience aud facts, as proven in California and other parts of the world.t It is owing to that circumstance that miners have coincd tho expression ‘‘pay dirt,” which means that stratum or those strata which contain the bulk of the precious metal. Iu some districts gold is found 30 to 50 fect above the bedrock in suflicieutly paying quantities to hydraulic, and in some shaHlow? banks gold is quite generally disseminated. Both at San Juan aud North Bloomleld the gold is more or less scattered throughont the deep drift, and diggings near Forest hill, Placer county, 20 to 60 feet above the bedrock, have yielded profits. The top gravel of the channel deposit which passes through Columbia hill, Nevada couuty, has, in several instances, been successfully washed. This is especially remarkable on account of the great depth of this deposit, which, from the explorations on Badger hill and Grizzly hill, is iuferred to he 600 to 620 feet deep. With such facilities as would be afforded hy a heavy grade, sufficient dump and cheap water deposits of this eharacter consisting of a fine light quartz wash, containing uo houlders nor pipe clay, though they contained an insignificant amount of gold per cubic yard, could he successfully work eatie the hydraulic method, Experieuce has proved, however, that the quantity of gold found in ‘‘top gravel” is insufficient to warrant ony large investment hased solely on its value. Under exceptional conditions and circumstances the upper strata have, in some cases, yeilded handsome returns, hut on the whole the general results have been anything but fortunate. It is a well established fact that the pay dirt is obtained, not from the washings of the entire hank, hut ehiefly from that stratum, or those strata § which are in most cases within eight or ten feet of the bedrock. . Where this is of slate upturued on its edges, the gold frequently penetrates ** it one or two feet, It also occurs in thin streaks of cemeuted gravel scattered bere and there in the alluvial deposits, and not unfrequently a fine lamina gold is found in the grass roots tt J This last mentioned circumstance is in no way localized, as similar facts have been noted in other countrics, Mawe calls attention to the existence of gold in the grass roots on Mount San Antonio,tt in Brazil, and Walsh states that gold was tirst discovered in the deposits between 8. Jose and 8. Joas, Brazil, by Paultistas, who, *Geologieal Survey of Canada, Report of the Proge838, 1303-66, p. 80,, t Deposits between Tagilsh and Ekaterin, Die Lehre von den Erzlagerstatten, Von Cotta, p. 556, See artiele on ‘Gold Deposits," by M. A. Selwin, Geologist of Victoria, Quarterly Journal Geo, See., 1858, y 583, See “Gold Deposits of Jaragua," slwnatcs des Mines, 1817, vol. ii. p. 202. See gold deposits of Santa Rita, Contagallo, and Minas Novas. Geology and Physical Geography of Brazil, Hartt, pp. 50, 51, 159, 160. See aecount of the gold fields of Yesso, “Mineral Wealth of Japan," Henry 8. Munroe, E. M., Transactions American inst, Mining Engs., June, 1876. Sce Hngineering and Mining Journal, Doeember 2d, 1876. { See description of the aufiferous deposits at Morac's and Growler’s Creeks, Yhe Gold Fields and Mineral Districts af Vietoria, R. Brough. Suiyth, p 84. § On the subject of tho relative position of gold in deposits, see report of Mr. Stutehbury, Government Geolist of N.S. W. See Dre Lehre von den Evzlagerstatten, ‘on Cotta, vol. i. p. 101. . . See aecount of the yold deposits at Nation's gully, New gully, Never Mind spur, Beechwood distriet, also workings at Balaarat, The Gould Fields aud Mineral Districts of Victoria, B, Brough. Smith, pp. 81, 82, 87, 131 and 173. ‘> Wade "‘Siluria," p. 456, vol. i, Russie and Ural Mountains;" p, 487, “ Diggings at tho Soimanofsk Minca,”* Murchison; also vide pp. 86, 106, “Gold Deposits in Woods Point Distriet and Windlass Hill,” Gold Iields of Victor ta, R. Brough. Smyth, +t In reference to the vecureneo of gold, tho followin. note, taken from the Engineering and Mining Journal, February 10th, 1877, p. 94, relative to the diseovery of pay gold in tho New Sonth Wales coal ineasures, will be found interesting. Mr. C. 8. Wilkinson, F. I. S., writes from the Geological Survey Offiee, Gulong, under date of November 25th, to the Mining Departnfent, ag follows: “During my examination of the Tallawang gold-fleld reserve, § observed the important faet that tho gold found in tertiary alluvial deposits at the old Tallawang and Clough's gully diggings has been chiefly derived from conglomerates In the eoal measures. These eonglomerates are assoeiated with beds of sandstone and shales eontaining the fossil plant of our eoal measures, the Glossopetris, * + + This is the first time that gold has been noticed to oeeur in payable quantity in the coal ineasures in the colony, and it is not uuworthy of remark that we here posseee one of the most aneicent ‘alluvial’ deposits in the world.” tt Mawe's Travels, p, 264, pulling tufts of grass, “found uumerous particles of gold entangled in the roots.’” The gold alluvia fouud near and along the banks of the Tueluinne river, Stanislaus couuty, present some striking examples of the distribution of the precious metal. The pay dirt in the Chesnau claim is coutined to within six feet of the bedrock, whilst iu the Sicard claim, situated ahout 600 feet sonth of it and across a ravine, with banks from 20 to 40 feet high, tbe Gold is mere generally disseminated as leng as there are no sand strata, but whenever the latter epee the pay is confined to near the bedrock, Sir Roderick Murchison, describing the gold alluvia of the rich wine of Pesbanka, near Bogoslofsh,+ says: ‘‘ Most of tho gold has heen extracted near the center of the detrital mass, whoso maximum thickness is about seven feet, and which is clearly divisible, as elsewhere, into two parts, viz.: overlying elay and shingle, and auriterous saud beneath,” At Minas Novas, in the Province of Minag Geraes, Brazil, the ‘greater part” of the gold is in a deposit called cascalho, which adjoius the decomposed hedrock. The cascalho is a conglomerate, composed of rounded quartz pehbles of various sizes, which have been eemented_ together with ferric oxide, ‘To this couglomerate the search for precious metals has heen chietly confined. Over this gravel lies a mass of red drift, varyiug in thickness from a few inches to 50 feet.”"£ The stratum of cascalho mined from the bed of tho river Jigitonhouha, at the Mandango diamond works consisted of the same material as that of the other gold districts of Brazil. Large conglomerate masses of rounded pebbles cemented together hy ferric oxide, found on the hank of this stream, occasionally contained gold and diamouds. Tho gold extracted from the cemeut gravel at Caparatra, situated higher up the river, was accompanied hy a great abundance of '' black oxide of iron. § Iu the Patricksville Light claim, Stanislaus eounty, Cal., the pay stratum is six or seven feet thick and adjoins the hedrock. ‘The gold is conceutrated in this gravel deposit as long as there are sand strata in tbe hank, hut with their disappearance it hecomes diffused throughout the detritus. Whilst working tbis claim a large hole in the bedrock 25 feet deep was bottomed. The bole was filled with gravel, hut no pay was obtained, The pay stratum was found to he ou a level with and a continuation of the pay stratum of the rest of the claim. On the other hand, at the Chesnau and French Hill claims, whenever these hollows are found, a large yield of gold is iuvariahly obtained. The experience of miners iu the gold fields of Victoria has led to the conclusion that ‘‘in large auriferous rivers gold is always found on the hars or point, and not in the deep pools or hends.”. . In substantiation of these facts are cited Reid's creek, Weol Shed, Twist’s Fall, or Yackandandah, near Oshorne’s Flat, and Rowdy Flat; at each of these places large holes were cleaned ont, and ‘only a few colors obtained, whilst shallow flats immediately below them were very rich.” At Freuch Hill, Stanislaus county, whcre the hedrock was undulating, and in depressions found around a little hill, formed by a sudden rise in the hedrock, the gravel paid hetter than in any other portion of the claim. The gold fields south of Miask**Jin the Ural mouutains, present a similar case, ali the undulating ground and depressions around conical hills heing the most productive in gold. The hulk of the pay dirt in the cement gravel of Nevada county is within the first 30 feet of the hottom. It was the result obtained hy the North Bloomiield gravel mining company from washing three anda quarter millions cuhic yards of top gravel (1870-74), yielding 2.9 cents per cubic yard, and leaving a profit of only $2,232.84, that determined capitalists interested in these claims to investigate the question of the comparative values of the upper and lower gravel deposits. * Walsh's Notices of Brazil, 1828-1820, vol. ii, p. 122. “The silver minos of Potosi wero diseovered by a Spanjiard, who, in ascending the niountain, seized a busb to assist him and, this giving way, he found the roots embossed with silver,” thussia and Ural Mountains, vol. i., p. 482. {Geology and Physical Geography of Brazil, Hartt. pp. 159-60. §Mawe's Travels, pp. 222-7, . The Gold Fields and Mineral Districts of Victoria, R. Brough, Smyth, p_134. “Russia and Ural Mountains, vol. i, p. 488. Tue CoLorapo Bripan,.—The decision of the Cabinet concerning the eontroversy between the Texas-Pacific and Southern-Pacific railways, as to the latter's bridge and road over the Colorado reservation, and is a manifest victory for the Central Pacific. It was based upon an argumeut that, although Congress alone has power to grant the right of way over public lands, yet it is neither the duty nor interest of military or civil power to interfere to preserve any improved means of access to a military reservation. The practical effect of the decision will be to give the California Company free permission indefinitely to run its trains over the hridge and across the reservation, as Congress is not at all likely to interfere. TuscaRoRA.—The Western Union Telegraph Company has completed its line to Tuscarora, Nev., making the distance from Elko by wire 44 miles. The distance hy stage is 48 miles. ARIZONA was visited hy heavy showers of rain during the last of Septemher.

October 13, 1877.] MINING AND SCIENTIFIC PRESS 233 Hydraulic Mining in California.* {By Avo, J. Bowls, Jr, A. B., Mlalng Engineer } Brief Outline of the General Topography of the Gold Regions of California. The topographical features of Califernia, as demenstrated by the explorations of the State Geological Survey, are found to be exceedingly simple, Tiree equidistaut parallel lines can be used in conveyiug a general idea of the physical geography of eentral California. A straight or “ain axial line,” whose ceurse would be north 31° west, (passing through the culminating peaks of the Sierras for a distance of 500 miles, can be assumed as the western boundary of the State. A second parallel drawn 55 niles weat ef the '‘niain axial line” will skirt the western base of the Sierra Nevada, along the edge of the foot-hills. A third parallel run equidistant from the second will represeut, ‘tas nearly ax possible, the western base of the Coast ranges,” ‘These pera iets divide the Stato into three belts, namoly, the Sierra, the great Valley ef California, and tho Coast ranges. “This arrangement of the physical features holds good for a length of 400 miles in the direction of the main axial line, comprising almost the whole of the agricultural aud the greater part of the miuing districts. "+ The section of the country which is of immediate interest to the miner ia the westcrn slope ef the Sierras. ‘These mountains, rising in a short distance {yom the Sacramento plains to elevations of ever 7,000 fect, with occasional peaks 10,000 and 12,000 fect high, are cut by numerous decp aud precipitous gorges or canyona, through which drains the inunense watcrshed of the Sierras, supplying the main rivers of the State, and ultimately emptying into the Pacitic ocean. Between these canyons, ridges or divides are formed, on top of which gold placcrs are found. These gold-bearing surface. deposits extend from Shasta in the uorth to Kern county in the soutb, the most extensive deposits occurring in Plumas, Sierra, Placer and Nevada counties. The term shallow placers is applied to deposits of gravel and earth whose thickness varies from a few inches to five or six feet in depth, to distinguish them from deep placers or detrital accumulations found in ancient channels covering large areas, and varying from 100 to several hundred feet in depth. The Discovery of the Gravel Deposits Containing the Precions Metal. The pionecr miner, after working out the river hars, followed up the stream to find ‘‘the source of the gold.” Its existence was discoyercd from slides, denudations, and hreaks in channels, which subsequent explorations proved to be tbe ancient river system of the State, whose general course is nearly at right angles to the present river system of California. The indefatigahle prospector, advancing further into the unexplored niountains, again discovered gravel heds at elevations of scveral thousand feet ahove the present water-level. The streams flowing through the precipitous canyons of the high Sierras aided materially in the development and discovery of the gold fields, Their watera were soon appropriated for gold washing, and thus was inaugurated the system of mining ditches, which to-day extends over several thousand miles, The immense gold-hearing drift inclosed hetween channel walls, or ‘‘rim rock,” as it is called, was explored hy means of tunnels driveu in from bordering canyons, tapping the bottom of the deposit, enahling the extraction of the pay stratum, which was suhsequently sluiced to extract the gold. This style of mining received the name of ‘‘deep placer mining "= Little hy little the “‘top dirt” of these deposits, composed chiefly of light soil, clay, fine gravel, and streaks of sand, was washed off, andin places considerahle gold was thus ohtained. Canvas hose was hrought into use to convey the water over the hanks for washing the dirt, and from this originated hydraulic mining. In the progress of the work strata were found composed of houlders, pehhles, quartz, saud, and various rocks cemented togetber, requiring the use of powder to hreak them up. The color of this cement was in places white or reddish, and sometimes hlue. Shafts sunk in these strata discovered the presence of gold in great ahundance, and a fresh enthusiasm was thus infused into grave] mining, already on the wane, as the river hars were becoming exhausted. The Gold Bearing Deposits of California. The auriferous deposits of California are ehietly contined to the western slope of the Sierra Nevada mountains. The principal counties in which placer mining is carried on are: Shasta, Trinity, Plumas, Sierra, portions of the cast side of Butte and Yuba counties, also Nevada, Placer, KE] Dorado, Amador, Calaveras, Tuolumne, Mariposa, and Stanislaus counties. ‘It ishcre,” says Professor Whitney, ‘‘that the helt of metamorphie slates and sandstones, which is peculiarly the gold hearing formation of the State, is developed to its greatest width, and least concealed from the miners’ explorations by the ~ A paper read before tbe American Institute of Mining Engineers, at the Wilkes-Barre meeting, May, 1877. t+ See vol. i. p.5, Geological Survey of Califurnia, J. D, Whitney, State Geologist. { Deep placer mining is now carried on in those sections of tho State where the rie: deposits are covered witb thick beds of lava, rendering hydraulic mining impracticable. presence of nverlying non-metalliferons formatiens. It ie here that the physical conditions have most favored the concentration of the geld in the detrital formatien, so that it conld be ohtained by simple washing, without the necessity ef mining for it in the selid rock, and perhaps mere réadily aud mere abundantly than any regien ever opened to seckers after the precious metal?’* The yold deposits are found in river channels, in hasina and en flats, alse as isolated rolling hills, and occur either as accumulations of gravel alene, restiug dircetly en the surface, or as accumnilations of detritus, consiating ef gravel, sand, drift, pebhlcs, and boulders of all sizes covered with lees and other volcauic products. Their geolegical ages are Post-Tertiary and Tertiary. Quantities of fossil wood and numerona remains of land and water animals have heen Color found in most every pan in this top gravel. } Good gravel. ‘\ Bluo gravel from top down for 50 feet, Averaged about 10 eolors to the pan. /. Streaks of clay throngh gravel, thiekest 8 inehes. Gold very fivo until green gravel was struck. Here soft and sandy. . Mueh quartz. Pipe elay disappeared. Tere appeared a little eement, Gravel coarser, some eement. Gold eoarser since striking green gravel. Here mueh eement. 180 190 Thin strata of sand. Last 8 ft. 5 to 20 cts, to pan Cement. Figures within the shaft indicate the nuniher of colors to the pan, every test made fron: 120 foet down ia here recorded, Sketch of Shaft No. 1—Malakoff—North Bloomfield Gravel Mining Company. found in the deposits, and are being constantly unearthed as the mines are worked. The auriferous alluvions mark the lines of ancient rivers, whose action on a grand scale was analogous to that which can he daily seen along the streams which receive the tailings from the hydraulic claims now being worked. Voleanie eruptions have iu places covered these deposits with lava and tufa, hundreds of feet deep. Denudatiou and erosion, the companions of ‘lime, have subsequently played their parts, and later in turn the product of volcanic activity has heen overlain with gold bearing detritus. These gravel channels are from a few hundred to several thousand feet wide, and range from the shallow placer to a drift 600 or 700 feet in depth. Their richness in gold varies in general, as well asin particular, in the many parts of the State. Ferruginous-colored spots, so well marked in ‘tupper or top gravel,” are not always as pro* Geological Survey of California, vol. i p, 214, J, D. Whitney. ductive in gold here as they are generally found to be in the gold alluvia of the Ural mountains. A black saud, cemposed chictly of glancing grains of magnetic iron, generally accompanies the precious metal, thongh it dovs net indicate its presence. Dr. 'T. Sterry Hunt, speaking of the erroncous impressions which prevail in refereuce te the presence of black sand in anrifcrons alluvions, very appropriately remarks that “similar black sand residues, eousisting chietly of various ures of iron (sometimes oxide of tin and other minerals), may he obtained from the washing of aliuost all sands and gravels derived from crystalline rocks, and that the occurrence of a black saud, therefor, in uo way indicates the presence of gold. When, hewever, this metal is present ina gravel, it, from its great weight, remains behind with the black sand and dense matters in the residue after washing.”* The Distribution of Gold in Gravel Deposits. It is not unfrequeutly stated that it is from the washing of the entire hanks that the gold is to be expected, it being disseminated throughout the whole deposit. That deposits are or are not auriferous for their cntire depth will not be discussed; but that gold is proportionately diffused throughout tho detritus, so that it could all he considered as ‘‘pay,” is denied by experience aud facts, as proven in California

and other parts of the world.t It is owing to that circumstance that miners have coincd tho expression ‘‘pay dirt,” which means that stratum or those strata which contain the bulk of the precious metal. Iu some districts gold is found 30 to 50 fect above the bedrock in suflicieutly paying quantities to hydraulic, and in some shaHlow? banks gold is quite generally disseminated. Both at San Juan aud North Bloomleld the gold is more or less scattered throughont the deep drift, and diggings near Forest hill, Placer county, 20 to 60 feet above the bedrock, have yielded profits. The top gravel of the channel deposit which passes through Columbia hill, Nevada couuty, has, in several instances, been successfully washed. This is especially remarkable on account of the great depth of this deposit, which, from the explorations on Badger hill and Grizzly hill, is iuferred to he 600 to 620 feet deep. With such facilities as would be afforded hy a heavy grade, sufficient dump and cheap water deposits of this eharacter consisting of a fine light quartz wash, containing uo houlders nor pipe clay, though they contained an insignificant amount of gold per cubic yard, could he successfully work eatie the hydraulic method, Experieuce has proved, however, that the quantity of gold found in ‘‘top gravel” is insufficient to warrant ony large investment hased solely on its value. Under exceptional conditions and circumstances the upper strata have, in some cases, yeilded handsome returns, hut on the whole the general results have been anything but fortunate. It is a well established fact that the pay dirt is obtained, not from the washings of the entire hank, hut ehiefly from that stratum, or those strata § which are in most cases within eight or ten feet of the bedrock. . Where this is of slate upturued on its edges, the gold frequently penetrates ** it one or two feet, It also occurs in thin streaks of cemeuted gravel scattered bere and there in the alluvial deposits, and not unfrequently a fine lamina gold is found in the grass roots tt J This last mentioned circumstance is in no way localized, as similar facts have been noted in other countrics, Mawe calls attention to the existence of gold in the grass roots on Mount San Antonio,tt in Brazil, and Walsh states that gold was tirst discovered in the deposits between 8. Jose and 8. Joas, Brazil, by Paultistas, who, *Geologieal Survey of Canada, Report of the Proge838, 1303-66, p. 80,, t Deposits between Tagilsh and Ekaterin, Die Lehre von den Erzlagerstatten, Von Cotta, p. 556, See artiele on ‘Gold Deposits," by M. A. Selwin, Geologist of Victoria, Quarterly Journal Geo, See., 1858, y 583, See “Gold Deposits of Jaragua," slwnatcs des Mines, 1817, vol. ii. p. 202. See gold deposits of Santa Rita, Contagallo, and Minas Novas. Geology and Physical Geography of Brazil, Hartt, pp. 50, 51, 159, 160. See aecount of the gold fields of Yesso, “Mineral Wealth of Japan," Henry 8. Munroe, E. M., Transactions American inst, Mining Engs., June, 1876. Sce Hngineering and Mining Journal, Doeember 2d, 1876. { See description of the aufiferous deposits at Morac's and Growler’s Creeks, Yhe Gold Fields and Mineral Districts af Vietoria, R. Brough. Suiyth, p 84. § On the subject of tho relative position of gold in deposits, see report of Mr. Stutehbury, Government Geolist of N.S. W. See Dre Lehre von den Evzlagerstatten, ‘on Cotta, vol. i. p. 101. . . See aecount of the yold deposits at Nation's gully, New gully, Never Mind spur, Beechwood distriet, also workings at Balaarat, The Gould Fields aud Mineral Districts of Victoria, B, Brough. Smith, pp. 81, 82, 87, 131 and 173. ‘> Wade "‘Siluria," p. 456, vol. i, Russie and Ural Mountains;" p, 487, “ Diggings at tho Soimanofsk Minca,”* Murchison; also vide pp. 86, 106, “Gold Deposits in Woods Point Distriet and Windlass Hill,” Gold Iields of Victor ta, R. Brough. Smyth, +t In reference to the vecureneo of gold, tho followin. note, taken from the Engineering and Mining Journal, February 10th, 1877, p. 94, relative to the diseovery of pay gold in tho New Sonth Wales coal ineasures, will be found interesting. Mr. C. 8. Wilkinson, F. I. S., writes from the Geological Survey Offiee, Gulong, under date of November 25th, to the Mining Departnfent, ag follows: “During my examination of the Tallawang gold-fleld reserve, § observed the important faet that tho gold found in tertiary alluvial deposits at the old Tallawang and Clough's gully diggings has been chiefly derived from conglomerates In the eoal measures. These eonglomerates are assoeiated with beds of sandstone and shales eontaining the fossil plant of our eoal measures, the Glossopetris, * + + This is the first time that gold has been noticed to oeeur in payable quantity in the coal ineasures in the colony, and it is not uuworthy of remark that we here posseee one of the most aneicent ‘alluvial’ deposits in the world.” tt Mawe's Travels, p, 264, pulling tufts of grass, “found uumerous particles of gold entangled in the roots.’” The gold alluvia fouud near and along the banks of the Tueluinne river, Stanislaus couuty, present some striking examples of the distribution of the precious metal. The pay dirt in the Chesnau claim is coutined to within six feet of the bedrock, whilst iu the Sicard claim, situated ahout 600 feet sonth of it and across a ravine, with banks from 20 to 40 feet high, tbe Gold is mere generally disseminated as leng as there are no sand strata, but whenever the latter epee the pay is confined to near the bedrock, Sir Roderick Murchison, describing the gold alluvia of the rich wine of Pesbanka, near Bogoslofsh,+ says: ‘‘ Most of tho gold has heen extracted near the center of the detrital mass, whoso maximum thickness is about seven feet, and which is clearly divisible, as elsewhere, into two parts, viz.: overlying elay and shingle, and auriterous saud beneath,” At Minas Novas, in the Province of Minag Geraes, Brazil, the ‘greater part” of the gold is in a deposit called cascalho, which adjoius the decomposed hedrock. The cascalho is a conglomerate, composed of rounded quartz pehbles of various sizes, which have been eemented_ together with ferric oxide, ‘To this couglomerate the search for precious metals has heen chietly confined. Over this gravel lies a mass of red drift, varyiug in thickness from a few inches to 50 feet.”"£ The stratum of cascalho mined from the bed of tho river Jigitonhouha, at the Mandango diamond works consisted of the same material as that of the other gold districts of Brazil. Large conglomerate masses of rounded pebbles cemented together hy ferric oxide, found on the hank of this stream, occasionally contained gold and diamouds. Tho gold extracted from the cemeut gravel at Caparatra, situated higher up the river, was accompanied hy a great abundance of '' black oxide of iron. § Iu the Patricksville Light claim, Stanislaus eounty, Cal., the pay stratum is six or seven feet thick and adjoins the hedrock. ‘The gold is conceutrated in this gravel deposit as long as there are sand strata in tbe hank, hut with their disappearance it hecomes diffused throughout the detritus. Whilst working tbis claim a large hole in the bedrock 25 feet deep was bottomed. The bole was filled with gravel, hut no pay was obtained, The pay stratum was found to he ou a level with and a continuation of the pay stratum of the rest of the claim. On the other hand, at the Chesnau and French Hill claims, whenever these hollows are found, a large yield of gold is iuvariahly obtained. The experience of miners iu the gold fields of Victoria has led to the conclusion that ‘‘in large auriferous rivers gold is always found on the hars or point, and not in the deep pools or hends.”. . In substantiation of these facts are cited Reid's creek, Weol Shed, Twist’s Fall, or Yackandandah, near Oshorne’s Flat, and Rowdy Flat; at each of these places large holes were cleaned ont, and ‘only a few colors obtained, whilst shallow flats immediately below them were very rich.” At Freuch Hill, Stanislaus county, whcre the hedrock was undulating, and in depressions found around a little hill, formed by a sudden rise in the hedrock, the gravel paid hetter than in any other portion of the claim. The gold fields south of Miask**Jin the Ural mouutains, present a similar case, ali the undulating ground and depressions around conical hills heing the most productive in gold. The hulk of the pay dirt in the cement gravel of Nevada county is within the first 30 feet of the hottom. It was the result obtained hy the North Bloomiield gravel mining company from washing three anda quarter millions cuhic yards of top gravel (1870-74), yielding 2.9 cents per cubic yard, and leaving a profit of only $2,232.84, that determined capitalists interested in these claims to investigate the question of the comparative values of the upper and lower gravel deposits. * Walsh's Notices of Brazil, 1828-1820, vol. ii, p. 122. “The silver minos of Potosi wero diseovered by a Spanjiard, who, in ascending the niountain, seized a busb to assist him and, this giving way, he found the roots embossed with silver,” thussia and Ural Mountains, vol. i., p. 482. {Geology and Physical Geography of Brazil, Hartt. pp. 159-60. §Mawe's Travels, pp. 222-7, . The Gold Fields and Mineral Districts of Victoria, R. Brough, Smyth, p_134. “Russia and Ural Mountains, vol. i, p. 488. Tue CoLorapo Bripan,.—The decision of the Cabinet concerning the eontroversy between the Texas-Pacific and Southern-Pacific railways, as to the latter's bridge and road over the Colorado reservation, and is a manifest victory for the Central Pacific. It was based upon an argumeut that, although Congress alone has power to grant the right of way over public lands, yet it is neither the duty nor interest of military or civil power to interfere to preserve any improved means of access to a military reservation. The practical effect of the decision will be to give the California Company free permission indefinitely to run its trains over the hridge and across the reservation, as Congress is not at all likely to interfere. TuscaRoRA.—The Western Union Telegraph Company has completed its line to Tuscarora, Nev., making the distance from Elko by wire 44 miles. The distance hy stage is 48 miles. ARIZONA was visited hy heavy showers of rain during the last of Septemher.