CHAPTER XV

GEOLOGICAL AND SOCIAL ANATOMY OF THE MINES.

1848-1856.

PHYSICAL FORMATION OF THE CALIFORNIA VALLEY-THE THREE GEOLOGIC BELTS PHYSICAL ASPECT OF THE GOLD REGIONS--GEOLOGIC FORMATIONS INDICATIONS THAT INFLUENCE THE PROSPECTOR- ORIGIN OF RUSHES AND CAMPS-SOCIETY ALONG THE FOOTHILLS-HUT AND CAMP LIFE-SUNDAY IN THE MINES-CATALOGUE OF CALIFORNIA MINING RUSHES-MARIPOSA, KERN, OCEAN BEACH, NEVADA, GOLD LAKE, LOST CABIN, GOLD BLUFF, SISKIYOU, SONORA, AUSTRALIA, FRASER RIVER, NEVADA, COLORADO, AND THE REST--MINING LAWS AND REGULATIONS -MINING TAX---DISCRIMINATION AGAINST FOREIGNERS.

THE largest and most important section of California, between latitudes 35° and 41°, may be divided into three geological as well as physical belts, beginning at the main axial line drawn from Mount Shasta through the leading summit peaks of the Sierra Nevada for nearly 500 miles. The limit of the first belt would be a line 50 miles westward along the edge of the foothills, touching at Red Bluff and Visalia. The next belt, of equal width, would be bounded by the eastern edge of the Coast Range, and the third belt by the coast line. A fourth belt may be added, which, extending eastward from the Sierra summit, falls partly within Nevada, and covers a series of lakes, arid depressions, and tracts marked by volcanic convulsions. South of the great valley, where the united ranges subdivide into low and straggling elevations,

1Prof. Whitney, upon whose Geol. Survey of Cal., i. 2 et seq., I base these observations, makes the belts 55 miles wide, and adds a fourth, eastward from the Sierra crest. The zonal parallelism of the metals in these belts was first observed by Prof. Blake.

this belt supplants it with vast deserts, the topography of which is as yet obscure, like that of the confused mountain masses of the northern border,

The second and third belts embrace the agricultural districts, with the broad level of the California valley; yet they contain a certain amount of mineral deposits. Solfataric action is still marked in the Coast Range, especially in the hot springs of the Clear Lake region. Its rocks are as a rule sandstones, shales, and slates of cretaceous and tertiary formations, with a proportion of limestone, granite being rare except in the south. The metamorphism of the sedimentary beds, chiefly chemical, is so prevalent as to render the distinction of eruptive rocks difficult. Most striking is the vast transformation of slates into serpentines, and partly into jaspers, the combination of which indicate the presence of valuable cinnabar bodies. In the sandstones of these cretaceous formations occur all the important coal beds so far discovered. The tertiary strata, chiefly miocene of marine source, but little changed, begin properly south of Clear Lake and assume importance below Carquinez, where they appear much tilted. South of latitude 35° bituminous slate predominates in the shale overlying the coarse sandstone, and contains deposits of superficial asphaltum, with promising indications of flowing petroleum. Below Los Angeles the rocks acquire more of the crystalline character of the Sierra Nevada, and in the Temescal range, with its granite, porphyry, and metamorphic sandstone, tin ore has been found. Along the San Gabriel range gold exists; but while pliocene gravels are frequent enough along the Coast Range, the metal seldom occurs in paying quantities.

The gold region is practically confined to the first belt, along the west slopes of the Sierra Nevada, intersected by nearly parallel rivers, and broken by deep cañons. An intrusive core of granite forms the central feature, which becomes gradually more exposed and extensive, till, in latitude 36-7°, it reaches almost

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from crest to plain. The core is flanked by metamorphic slates of triassic and jurassic age, much tilted, often vertical, the strike being generally parallel with the axis of the range, and in the south dipping toward the east. This so-called auriferous slate formation consists of metamorphic, crystalline, argillaceous, chloritic, and talcose slates. In the extreme north-west it appears with though subordinate to granite. Gradually it gains in importance as the superimposed lava in Butte and Plumas counties decreases, and north of the American River it expands over nearly the entire slope; but after this it again contracts, especially south of Mariposa; beyond the junction of the ranges it reappears in connection with granite. To the same formation are confined the payable veins of gold quartz, chiefly in the vicinity of crystalline and eruptive rocks. They vary in thickness from a line to twoscore feet or more, and follow a course which usually coincides with that of the mountain chain, that is, north-northwest with a steep dip eastward. The most remarkable vein is the extensive mother lode of the Sierra Nevada, which has been traced for over 60 miles from the Cosumnes to Mariposa.*

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The slate formation is covered by cretaceous, tertiary, and post-tertiary deposits, of which the marine sedimentary, chiefly soft sandstone, made up of granite débris, occurs all along the foothills, conspicuously in Kern county. The lava region extends through Plumas and Butte northward round the volcanic cones headed by mounts Lassen and Shasta, whose overflows have

2 The quartz occurs in granite, and in the Coast Range, but rarely in paying quantities.

3 The richer streak along the footwall, or in the lower side of the lode, is often the only payable part. Sometimes a lode contains streaks of different qualities and appearance. According to Marcon, Geol., 82, the richest veins of California are found where sienitic granite and trap meet. Branches and offsets often cut through the slate beds at considerable angles.

It runs south-east, while veins in the Sacramento valley turn more nearly north and south. Its dip is 45° to the north-east. The white quartz is divided into a multitude of seams, with gray and brown discoloration, and with small proportions of iron, lead, and other metals. The accompanying side veins contain the rich deposits. Blakeslee. The width may average 30 feet, the thickness from 2 to 16 feet, though deepening to many rods.

hidden the gold formation of so large an area. The wide-spread deposits of gravel are attributed to a system of tertiary rivers long since filled up and dead, which ran in nearly the same direction as the present streams, and with greater slope and wider channels. Eroding the auriferous slates and their quartz veins, these river currents spread the detritus in deposits. varying from fine clay and sand to rolled pebbles, and bowlders weighing several tons, and extending from perhaps 300 or 400 feet in width at the bottom to several thousand feet at the top, and from a depth of a few inches to 600 or 700 feet. The whole mass is permeated with gold," the larger lumps remaining near their source, while the finer particles were carried along for miles. The most remarkable of these gravel currents is the Dead Blue River, so called from the bluish color of the sand mixed with the pebbles and bowlders, which runs parallel to the Sacramento some fifty miles eastward, with an average width of a quarter of a mile. The depth of detritus averages three hundred feet, and is very rich in the lower parts, where the débris is coarser and full of quartz. Although the so-called pay dirt, or remunerative stratum, lies in alluvial deposits nearly always within ten feet of the bedrock, and frequently permeates this for a foot or so in the slate formations, yet the top layers often contain

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"Fossil wood and animals are found here, and occasionally layers of lava and tufa often sedimentary, and some superimposed, others in alternation. The deposits at La Grange, Stanislaus, in a distance of 1 miles cross 4 widely varying formations, with elephant remains embedded. Some of these dead rivers present peculiar features; instance the Tuolumne table mountain, 30 miles long by half a mile in width, which consists of a lava flow upon the rich gravel of an ancient river-bed. The waters forced aside by this flow washed away the banks on either side, leaving the lava isolated above the surrounding soil, with steep sides and a bare level top.

The smaller and smoother the gold, so the gravel, and nearer the bottom lands.

The driftwood in it, the course of the tributary gravel currents, the position of the bowlders, etc., indicate a stream, and one of mighty force, to judge by the size of the bowlders; yet some scientists object to the river-bed theory. A line of towns stands along its course through Sierra and Placer counties, 65 miles, which shows a descent from 4,700 to 2,700 feet, or 37 feet per mile. But subterranean upheavals may have effected it. North of Sierra county it is covered by lava, and south of Placer it has been washed away or covered by later alluvium.

gold in payable quantities, even in the upper portions of high banks, which can be washed by cheap hydraulic process.

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The miners were a nomadic race, with prospectors for advance guard. Prospecting, the search for new gold-fields, was partly compulsory, for the over-crowded camp or district obliged the new-comer to pass onward, or a claim worked out left no alternative. But in early days the incentive lay greatly in the cravings of a feverish imagination, excited by fanciful camp-fire tales of huge ledges and glittering nuggets, the sources of these bare sprinkling of precious metals which cost so much toil to collect. Distance assists to conjure up mirages of ever-increasing enchantment, encircled by the romance of adventure, until growing unrest makes hitherto well-yielding and valued claims seem unworthy of attention, and drives the holder forth to rove. He bakes bread for the requirements of several days, takes a little salt, and the cheering flask, and with cup and pan, pick and shovel, attached to the

Fine gold has frequently been found in grass roots, as observed also in Walsh's Brazil, ii. 122. At Bath a stratum 100 feet above the bed-rock was drifted profitably, and the top dirt subsequently washed by hydraulic method. In Nevada county the bulk of pay dirt is within 30 feet of the bottom. The deposits at French Hill, Stanislaus, show that an undulating bed-rock gathers richer dirt, yet in certain currents bars and points catch the gold rather than pools and bends, as proved also in Australia. Gold Fields of Victoria, 134. The sand layers of the Sierra Nevada drifts contain little gold. In the gravel strata at Malakoff, Nevada county, a shaft of 200 feet yielded from 2.9 to 3.8 cents per cubic yard from the first 120 feet, from the remainder 32.9 cents, the last 8 feet producing from 5 to 20 cents per pan. Bowie's Hydraulic Mining, 74-5. There are also instances of richer strata lying some distance above a poor bed-rock. The dead rivers are richer in gold than the present streams, and when these have cut through the former they at once reveal greater wealth. In addition to Cal. Geol. Survey, see Browne's Min. Res., 1867; Whitney's Aurif. Gravels, 516, etc.; Laur. Gisement de l'Or. Cal., Ann. des Mines, iii. 412, etc.; Silliman's Deep Placers; Phillip's Mining, 37 et seq.; Bowie's Hydraul. Mining, 53 et seq.; Hittell's Mining, 66 et seq.; Balch's Mines, 159 et seq.; Trask's Geol. of Coast Mts, 42-68; Hayes' Mining, v. 393, 398; ix. 6 et seq.; Cal. Jour. Sen., 1853, ap. 59; 1856, ap. 14; Sac. Union, Mar. 12, 27-9, Aug. 10, Oct. 13, 27, 1855; Tyson's Geol. Cal.; Cal. Geol. Survey, Rept Com., 1852. Blake, in Pac. R. R. Rept, v. 217 etc., classified the placers as coarse bowlder-like drifts, river drifts, or coarse alluvium, alluvial deposits on flats and locustrine deposits made at the bottom of former lakes, all of which have been greatly changed by upheavals, transformed river systems, and the erosion of currents. Additional geologic points are given in connection with the districts and

counties.

HIST. CAL., VOL. VI. 25