The mineral wealth, climate and rain-fall, and natural resources of the Black hills of Dakota

Front matter

New York

State College of Agriculture

At Cornell University

SECTION II. THE FEENCn CREEK DISTRICT

In the French Creek district is embraced all the area of granitic and schistose rocks surrounding Harney's Peak and forming the southern portion of the Hills, bounded by Spring Creek on the north, and including the placer-gravels in the valleys of Wiwi Creek, Custer's Gulch or French Creek, Amphibious, Minnekata, and Bed Canon Creeks, streams draining this region and emptying into the South Pork of the Cheyenne.

Before discussing the value and extent of the gold-deposits, it is necessary to describe briefly the topography and geological formation of

RESOURCES OF THE BLACK HILLS. y

this district, which presents, ia the immense development of granitic rocks, a feature peculiar solely to this section of the Black Hills.

The Harney's Peak range, and the country included between it and the foot-hills oq the easteru slope, is an exceedingly rugged and mountainous region, heavily wooded with pine and cut into innumerable deep ravines by a net-work of small streams flowing in a general southeasterly direction, but sinking before they reach the plains. These small creeks are full of beaver-dams, and the bottoms of the gorges are overgrown with a perfect jungle of oak, elm, birch, elder, and grapevines, making it almost impossible to descend the valley of the stream, and compelling the explorer in this wilderness to travel across the steep and broken rocky ridges, where, except he be .fortunate enough to climb some of the few commanding peaks, he cannot see but a short distance in any direction, owing to the densely-wooded and broken character of the region. It is useless to look for any main divide which can be followed in traversing this mountainous section; the whole area is broken into innumerable granite peaks and ridges without any apparent system whatever, except that the drainage is in a general southeasterly direction toward the open plains. The effects of erosion are everywhere strongly marked, and the peculiar topography of the region is due to the resistance of the hard granite and the yielding of the micaceous schists to the action of time and water.

The prominence of the granite, which in huge, serrated ridgesrises on every side, is due more to erosion than to _any elevation caused by its intrusion ; yet the granite, though so unyielding, shows by the rounded and pinnacled forms assumed by the peaks, that time has affected it as well, but in a less degree.

To the northeast of Harney's Peak is an area of slates, which properly belongs to the Spring Creek district, but with that exception this section is almost universally granitic, the schists, wherever they occur, being concealed by the debris resulting from the denudation of the granite ridges that tower far above the surfece of the softer rocks.

Harney's Peak, having an altitude of 7,403 feet above the sea, is the culminating point of this great intrusion of granite, and forms the most conspicuous landmark in the Black Hills, visible from the plains to the south and east for a distance of more than fifty miles from the foothills.

The Park region, at the west and southwest of Harney's Peak, is a most agreeable contrast to tBe inaccessible wilderness to the east. Broad glades of level grass-land extend between the parallel ridges of granite and groves of pine cover the rocky hills wherever there is sufScient soil to support their growth. Isolated peaks of granite, rounded by erosion and weathering into dome-shaped and castellated forms, rise from the open and level surface, which everywhere is carpeted with the finest grass, giving a beautifully picturesque and park-like scenery to the region.

The smooth surface of the parks and the peculiarities in the topography are due to the parallel ridges of granite resisting the denudation, which has excavated the broad swales in the intervening softer schists, and indicates that the orginial surface of the formation was far above the present level.

The granite is conform able to the stratification of the inclosing schistose

rocks, having been intruded between the layers, the only direction in

which the micaceous rocks are readily fractured. This conformability

, is not perfect, as it would be were the granite the result of metamor-

phic action on a layer of the schists, but the granite ridges often occur

10 ' KESOUECES OF THE BLACK HILLS.

traversing the park as a broken range of lenticular peaks on the same line of fracture, resembling, on an enormously-magnified scale, a well-known form of segregated quartz-veins. Narrow dikes of granite traverse the schists, often not more than two or three feet in width and of regular thickness, continuing uniformly for several hundred yards parallel to the stratification, and being harder t-han the schists, have been left by erosion standing like walls several feet above the surface of the ground. Where the surface of contact of the granite and the schists is exposed, the sides of the dike are seen to be smooth surfaces, often beautifully marked with slickensides exceeding in the polished and striated markings any specimens of the walls of mineral veins which have ever come under my notice.

The sides of the lenticular masses of granite forming the low ridges show slickensides and vertical striated surfaces, but not nearly in so marked a degree as the narrow dikes.

The granite is very coarsely crystalline, largely comiiosed of white or flesh-colored feldspar, intermixed with quattz and mica, (muscovite,) with black tourmaline in large hexagonal crystals as an associated mineral. Quartz occurs disseminated through the mass of the feldspar in small grains and in nodules between the crystals. Segregated veins and irregular masses of quartz occur in the granite ridges, generally white, vitreous, or translucent, frequently of a beautiful deep rose-color, but everywhere apparently free from any traces of valuable minerals, or any considerable quantity of gold.

The schistose rocks are in great variety, mica-schist being the prevailing form, often garnetiferous, and merging into talcose, chlorite, and quartz schists.

The minerals found in the schists are few in number. Small garnet-crystals are very abundant ; a few specimens of hornblende, epidote, and staurotide were seen, but they occur but rarely in these rocks. Veins and ledges of ferruginous quartz are found traversing the schists between the granite ridges or dikes to which they are parallel. These ledges are not true fissure-veins, that is, they do not intersect the strata at an angle to the stratification, neither are they segregated veins, but occur filling continuous and regular fissures between the lamellsB of the schists formed in the folding of the rocks, and are in fact interlaminated fissure-veins.

The quartz is often mixed with a large proportion of brown and yellow oxides of iron, resulting probably from the decomposition of pyrites, and the gold now found in the gravel-deposits along the streams has been derived from the disintegration and denudation of these ledges in the schists.

But little prospecting could be done in the numerous quartz-veins of this district, for want of time and proper tools. The miners reported gold in small quantities from several veins which they discovered and opened.

^ear the stockade on French Creek a mass of schist was noticed about 150 feet in length, upturned on edge and completely inclosed by a broad rim of granite. This fragment of schist was traversed by a ledge of quartz and limonite several feet in width, conformable to 'the stratification, and cut off at each end by the subsequent intrusion of the granite. From the uniformity in the composition and appearance of the granite from all parts of the Harney's Peak range, the dike character of the ridges, the presence of slickensides, and the observed instances of inclosed fragments of schists, I can but regard the granite of this region as injected. There are occurrences of small, narrow veins of feldspar leading from the granite into the schist, probably deposited by chemical solutions accompanying the intrusion, which would seem to indicate that the fluidity of the injected granite was due more to the presence of water than to the intensity of the heat.

French Creek rises in the level park country southwest of Harney's Peak, among granite, gneiss, and schistose rocks, and flows in a generiil easterly and southeasterly course about fifteen miles, until, entering a deep canon in the limestone formation, it sinks among the bowlders in the bed of the channel and disappears before reaching the foot-hills, continuing as a dry arroyo, with water-holes at intervals, to the Cheyenne. Near its head it is a sluggish stream with long stretches of slackwater ; in midsummer, notwithstanding frequent showers of rain, drying up to a chain of water-holes. A few miles below the stockade it is swelled by springs and side branches to a creek 10 to 15 feet in width and about 8 to 12 inches deep, flowing with a moderately-rapid current until it is lost in the canon.

Gold was discovered in gravel-bars on French Creek early in August, 1874, by Eoss and McKay, miners accompanying the expedition under command of General G. A. Custer, but from want of time they were unable to ascertain definitely whether the gold existed in paying quantities, although obtaining by a few days' work quite encouraging prospects.

About three weeks later this field was visited by the Kev. S. D. Hinman, with an escort from the agencies on White Eiver, iti search of a suitable location for a reservation, but not finding any evidences of gold, on their return they threw some discredit on the reports of the existence of the precious metal in the Black Hills.

A party of twenty -five miners from Sioux City reached French Creek December 23, 1874, and built a stockade and cabins near the location of General Custer's camp. They passed the winter prospecting very industriously for gold in the vicinity, opening several quartz-ledges in the schistose rocks of the park, and sinking pits on the flats and gravel-bars along the stream.

Before cold weather was over and the frost out of the ground so that the diggings could be opened on a scale large enough to practically test the richness and extent of the gravel-deposits, these miners were re- ■ moved by the military to Fort Laramie.

When (June 16) I reached French Creek, about fifteen miners were found camped four miles above the stockade, where they had been at work for several weeks, and had staked off claims, built small dams, and were digging ditches preparatory to commencing sluicing on the bars along the banks of the stream. These miners were very enthusiastic in regard to the mineral wealth of the gulch ; they were reporting from 5 to 27 cents to the pan from the pay-gravel, and made the most extravagant statements as to the yield which would be obtained as soon as they commenced working with sluices. But they were working under unfavorable circumstances; the water-supply was very small, not exceeding 60 miners' inches, with every indication that it would soon fail entirely, and the grade of the valley was so small that it was difficult to get a good head of water for sluicing. On testing, by washing, the pay-gravel from the dilferent prospectmg holes already opened, with a pan, and weighing the gold obtained, it was found that the usual yield along the stream was from four to eight colors to the pan, (about one-tenth to one-fifth of a cent,) and, in favorable and somewhat limited localities, from half a cent to as high as one and a half cents were obtained from the gravel from off bed-rock. The gravel-bars were rich enough in gold to pay, if extensively worked under more favorable cir-

12 * EESOURCES OF THE BLACK HILLS.

cumstances, but too poor to yield a remunerative return for the labor employed, except in a few limited deposits of gravel near the extreme head of the stream.

The next day the following dispatch, embodying all the information in regard to the gold-field that had been obtained to date, was sent by courier to Fort Laramie and telegraphed to Washington :

Camp on Fbench Creek, Near Harney's Peak, _

To Hon. E. P. Smith,

Commissioner of Indian Affairs, Washington, D. C. :

I have discovered gold in small quantities on the north hend of Castle Creek, in terraces or bars of quartz gravel.

Arrived here yesterday. About fifteen miners have located claims on the creek above here, and have commenced working. Gold is found from Castle Creek southwardly to French Creek at this point ; the deposits are almost wholly in Dakota. The region has not been fully explored, but the yield of gold thus far has been quite small, and the reports of the richness of the gravel-bars are greatly exaggerated.

On French Creek the deposits of gravel are very unfavorably situated. The water-supply is small and failing, and the grade too little to admit of the tailings being carried off by the stream.

The prospect at present is not such as to warrant extended operations in mining.

WALTER P. JENNEY, E. M., Geologist Exploration of the Black Sills.

The fact of the existence of gold caused considerable excitement among the soldiers and teamsters of the escort, and quite a number were busily engaged in prospecting along the creek, sinking holes to the bed-rock wherever there was the slightest indication of a deposit of gravel, or cleaning out old prospecting-shafts dug by the miners the preceding winter, and panning the pay-gravel which had been reported to be so rich in gold. But the results of their labor were so discouraging — generally only a few small " colors " would be, obtained from a pan of gravel, and rarely more than three-quarters of a cent to the pan in the richest layer of pay-dirt from off bed-rock — that after a few days they abandoned the search for the precious metal and did not resume it for more than two weeks, until the discovery of a very encouraging prospect on a bar near the stockade caused a renewal of the excitement for a time, an account of which will be given farther on.

In examining the gravel-deposits along the valley of French Creek, advantage was taken of the numerous prospecting shafts already sunk by the miners, and in the few places remaining untried which gave any indication on the surface of the existence of valuable underlying gravel-beds, shafts were sunk to bed-rock by the miners assisting me in the work. The first tests were made by washing several pans of the pay-gravel in the usual manner, and if the result obtained was at all encouraging, the deposit was more extensively tested by washing a measured quantity of the pay-dirt in a rocker and weighing the gold obtained. Finding that the best prospects in the gulch were from gravel from a prospecting shaft on a dry branch of French Greek, about live miles above the stockade, the following test was made to determine as accurately as possible the richness of the deposit :

The shaft was first cleaned out and a sufficient quantity of the pay-gravel drifted out from off bed-rock, carefully averaged, measured, and washed with the greatest care in a rocker, every precaution being taken to prevent any appreciable loss of tine gold carried over the riffles by the muddy water. The result was as follows : 9 buckets gravel = 3.12 cubic feet, gave 0.370 gram, of gold in small flat scales and grains :

EESOURCES OF THE BLACK HILLS. ' 13

0.370 gram. = 5.7 grains troy = $0.23, or about one and one-fourth cents to the pan.

This would indicate a yield of $1.87 per cubic yard of the pay-grarel which formed a layer on bed-rock about a foot in thickness.

In the above calculation an average bucket of gravel is taken at 600 cubic inches, or 75 buckets equal one cubic yard. A pan is about half a bucket, giving 150 pans of dirt to a cubic yard. I have estima;ted the value of the gold to be $19.50 per ounce in gold coin.

The gravel from a shaft some distance below on the stteam, tested in a similar manner, gave the following result: 10 buckets dirt ^3.42 cubic feet, yielded 0.020 gram, gold ; 0.020 gram. = 0.3 grains troy = 0.012 cent, or 9 cents per cubic yard, equal to one-twentieth of a cent to the pan. This latter gravel was very poor in gold, but that washed in the preceding test was correspondingly richer than the average of the gravel opened at that time along the creek. Near the stockade the result of the prospecting showed that the richest gravel was from a hole sunk to bed-rock on the bank of the creek, four pans of the pay-dirt giving \ grain troy = 3 cents gold, or f of a cent to the pan. Washing 12 buckets of this gravel in a rocker, yielded 4J grains troy of gold = 17 cents, or $1.12 per cubic yard ; nearly the same result as was obtained with the pan.

Most of the prospecting holes had been sunk early in spring, when the ground was full of water and the locations selected with regard to the rim-rock, so that the bed-rock might be reached before the depth of the shaft became so great that it would be flooded with surface-water. In order to test the deeper channels in the flats near the stockade, a place was selected where the configuration of the surface of the ground indicated an old channel filled with gravel to the present surface of the bar.

A shaft 5 feet by 7 feet was sunk to bed-rock, which was reached at a depth of 15 feet, passing through gravel filled with large water-worn bowlders 2 to 3 feet in diameter. Four men were constantly employed for three days in sinking this shaft ; the bowlders had to be broken with sledges and hoisted out with a windlass, and the water was so troublesome as to require constant bailing to keep the shaft dry. The bedrock was found to be granite. On cleaning up the whole surface the size of the bottom of the shaft and panning the gravel, not a color of gold was obtained, a result which was unlocked for by the miners, the gravel passed through having been quite promising in appearance.

Having forwarded to Washington a written report embodying the results of the prospecting and exploration made up to date, (June 25,) I left French Creek, and, accompanied by my miners, made an excursion north, for the purpose of examining the valleys of Spring aiid Eapid Oreeks, and on my return, July 8, 1 found that some new discoveries had been made, and considerable work done by the miners in my absence.

A party of miners about five miles above the stockade had put in a small sluice, and reported'that they obtained by one day's work 27 pennyweights of gold, or nearly $27; three men being employed in shoveling the gravel into the sluice. Unfortunately, the work on this bar was stopped by the stampede to the new discoveries in Spring and Castle Creeks, before it could be thoroughly tested and the richness of the deposit proved to be constant and regular.

John W. Allen, of Cheyenne, an experienced miner, and one of the best prospectors I ever knew, in a letter to the Chicago Inter-Ocean, gives the results of this sluicing, in which he assisted the owners of the bar.

14 EESOURCES OP THE BLACK HILLS.

Cheyenne, Wyoming Tereitory,

Augmt 30, 1875.

To the Editor of the Inter-Ocean :

I waited last spring for the country to be thrown open by this Indian treaty now pending, and becoming impatient I concluded to do as hundreds of others did, to start into the hills, and on the 12th of July landed in Custer's Paris, and being an experienced miner, I had doubts in regard to French Creek paying, because of there being no fall to the creeii and scarcely any water. But I found one set of sluice-boxes about to be set up, and I went to wor]£ and helped to fix them, and then worlied one day and weighed the dust, and found that the ground paid $9 per day to the hand, of fine dust, although

am sure this creek will not average that all the way through the gulch.

JOHjST W. ALLEN.

John Eoberson, an old California miner of the "days of forty-nine," had discovered very good prospects on an elevated bar near the stockade, and, building a dam, conveyed the water from the creek in a small ditch to the face of the drift. In the mean time the soldiers had become quite excited over the discovery, and were hard at work with pans and rockers, washing the pay-dirt from off bed-rock. For several days they were quite successful. From 16 to 26 colors were obtained to the pan. One soldier found a piece of gold valued at 20 cents ; another a small nugget weighing about a pennyweight, worth 97 cents, and 24 buckets of gravel gave, on washing, an average of 12 cents gold. On drifting in on the bar the pay-streak rose, and was found among the bowlders nearly 18 inches above the bed-rock. The section of this gravel- deposit was as follows :

Soil 1 foot.

Gravel and bowlders 4 feet.

Clayey compact gravel containing the gold 6 inches.

Decomposed bed-rock and bowlders 1 foot.

Micaceous schist forming bed-rock.

The sluices were soon in place, and this bar most thoroughly tested, under the direction of Mr. Eoberson. The result of the first day's work of eight hours, four men being employed most of the time, was 2 dwt,

8 gr. Troy of coarse gold, valued at $2.30.

The second day, not only the gravel was put through the sluce, but the whole surface of the bed-rock exposed by both days' work was most carefully cleaned up and washed. The return, however, was but 1 dwt.

9 gr. Troy of gold, equal to $1.10.

The work of both days may be summed up :

4 men 1 day, result , $2 30

6 men I day, result 1 10

10 men 1 day, result 3 40

or a yield of 34 cents per day per man.

This result was a disappointment to every one, and seemed to indicate that the richness of the gravel at first obtained w.as due to a concentration of the gold on rim-rock, and that the cleaning of the bed-rock probably yielded only a very small proportion of the gold, the greater quantity being derived from the compact gravel.

The gold obtained was in coarse, flat scales, or small, spongy grains, and was quite deceptive in its appearance, nearly all the miners guessing the weight of the dust very much too high.

Gold was found in small quantities in gravel deposits along the numerous creeks flowing east from Harney's Peak, but the region is so inaccessible, and so many difficulties are encountered in attempting to prospect it, that but little could be done by myself and assistants in that area, while the rush to the discoveries on Spring and Castle Creeks carried all the miners in the hills far to the north, and left this region but partly prospected.

Some prospecting was done on Amphibious, Minnekata, and Eed Caiion Creeks, small streams draining the southern portion of Custer's Park. On Amphibious, near its headwaters, a few colors of gold were obtained from small gravel-deposits, but the water-supply was so small, the stream being dry at the time, that prospecting was very difiicult. About five miles below the head of this creek, a number of dry ravines enter it from the east, cutting deep into the schists and slates. In these ravines flo"i>it- quartz was found, showing, on breaking, visible particles of gold, but the quartz was not traced to the ledge from which it had been originally derived.

Minnekata or "Hot Water" Creek, so named by the Indians from the warmth of the water, which has a temperature of 74° P., although rising in large warm springs in the Carboniferous limestone, has a deep deposit of quartz- gravel on its east bank, about two miles below its source. This gravel is derived from the wash from the Hills, and is composed of bowlders of rocks and quartz cemented by sand and lime to a loosely cohering conglomerate, forming a bluff on the bank of the stream. Similar deposits are to be seen at intervals among the foot-hills at the edge of the plains all along the eastern slope from this stream as far north as Box Elder.

On Eed Canon Creek several tests were made of the gravel-deposits, but nothing of value found. This stream is on the extreme western edge of the gold-fields, and rises partly in the limestone, contains but little water and drains but a limited area of the schistose rocks.

The gravel-deposits elevated above the present level of French Creek showed often a local concentration of gold on the outer edge of the bed-rock from the repeated washing away of the gravel by floods or heavy rains, leaving the gold contained in it behind. Though giving a very encouraging prospect at first; on driving an open cut a few yards into the bar where the gravel was undisturbed, the richness of the pay-dirt rapidly decreased until it equaled the true average of the whole deposit, thus showing that the result at first obtained was only a " rim-rock prospect."

The richest layer in the pay-gravel was rarely on bed-rock, but usually from 10 to 20 inches above it, forming the upper surface of the stratum of compact clayey gravel mixed with fragments of decomposed bed-rock which had caught and retained the greater portion of the gold.

The gravel-bars along French Creek, for several miles above and below the stockade, were examined wherever there was the slightest indication or probability of gold existing in paying quantities with results similar to those already given, and, as might be expected from the level character of the valley, the gravel-deposits were richest around its head branches, and proved regularly poorer in gold as the distance below its source increased.

Excepting Castle Creek no stream in the Hills was prospected the past season to anything like the extent that the gravel-deposits on French Creek were subjected to. The whole bottom of the valley for nearly six miles was full of prospecting pits. Each new party of miners on arriving in the Hills first visited Custer Gulch, as it was called, and expended their surplus energy and enthusiasm in sinking a number of prospecting holes before proceeding elsewhere in search of gold. But the results obtained by these miners were very poor, except in a few

18 EESODECES OF THE BLACK HILLS.

dred and fifty square miles, elevated about 6,000 feet above the sea, characterized by low, rounded hills, and ridges, wooded with pine of medium size, interspersed with numerous small parks and grassy valleys, well watered by the springs and brooks forming the sources of this stream. The prevailing rocks of this region are mica-schists, often garnetiferous and merging in all gradations into talcose and quartz schist, and strata with thin slate-like lamellae, containing but traces of mica.

Quartz occurs, distributed abundantly in the schists as thin segregated veins, parallel to the bedding, or in irregular bunches, not continuous in the strata. It is found crystalline, white, red, or rose tinted, and, with the exception, probably, of gold, appears to be free from any other minerals.

The abundance of quartz forms a serious annoyance in prospecting for ledges, the whole country being covered with float-quartz of every variety, rendering it difficult to trace fragments found to contain gold to the veins from which they were derived. The first tests for gold on Spring Creek were made on a small branch flowing west from Harney's Peak and emptying into the main stream about three miles above Newton's Fork. The gravel, resulting from the wash of the granite of the Harney's Peak range, failed to give a trace of gold on panning, but on descending the branch and testing the gravel, as soon as we had entered the mica and quartz schists, small colors of gold were obtained.

The different strata were encountered in the following order, in proceeding down this branch :

1. Coarsely crystalline, white feldspar granite of the Harney's Peak range.

2. Metamorphic schist, (gneiss.)

3. Mica-schist, with segregated quartz-veins containing traces of amorphous graphite.

4. Quartz-schist, having a slaty structure alternating with strata of mica-schist ; the whole formation dipping 45° west.

In descending Spring Creek, the first gravel-bars are seen about five miles above Newton's Fork, elevated from 20 to 40 feet above the present level of the stream on flat points and benches of mica or quartz schist.

On making an open cut into these bars on bed-rock, the gravel is found to be almost exclusively composed of quartz, and to yield, on panning, small quantities of gold, from one color to half a Cent to the pan. Better results were obtained from drifts run in on toed-rpck in the flats near the edge of the stream. The gravel is full of mica and small garnet-crystals, resulting from the disintegration of the schists, and the gold is associated with black sand and bright scales of iron-ore.

To test the deeper channels in the flat, a shaft 5 by 8 feet was sunk with considerable difficulty to bed-rock, which was reached at a depth of 13J feet, passing through the following deposits :

Black peaty soil 4 feet.

Brown colored, loose, light gravel 2 feet.

Compact white quartz- gravel, containing about half a cent to

the pan of coarse scale-gold 2 feet.

Loose quicksands with bowlders, yielding only flue colors of

gold 4 feet.

Decomposed bed-rock, with colors of coarse scale-gold IJ feet.