USA > California > Amador County > History of Amador County, California, with illustrations and biographical sketches of its prominent men and pioneers > Part 29
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As all stratified rocks, or at least such as we are likely to meet with, were once horizontal, let us go back in imagination to the time when the deep sea was rolling over our own Sierra Nevadas. We must not hesitate in the cause of science, to sink also the Utah basin, and even the Rocky Mountains. It matters not that some of our sarcastic friends tell us that we have no ground to stand on; that will appear presently. We have now the sea, deep as the Atlantic, rolling over the future Great West. Only a portion of the continent, perhaps the White Mountains and Apalachian range, are yet out of the sea. It is during these immensely long periods that the slates and the rocks, the future sources of min- eral wealth, are deposited in the deep sea. Age after age (time is no object) the deposit goes on, perhaps the thousandth part of an inch a year. Minerals, suspended or in solution in the water, may be brought and deposited, either by precipitation or by gravity, and compounded into the mass. Every one has seen how iron is precipitated by a small particle of sea-weed along the shore, the iron in turn uniting with something else-lime, salt, magnesia, potash, silex, alumina, and, perhaps, gold and silver, through chemical changes that are constantly inter- mingling, changing, and forming new compounds. The coral insect goes to work, and, laying hold of cach particle of lime that comes along, incorporates it into a solid reef-the future limestone ranges of the continent that is forming. The smallest insect, the infusoria, finding the water charged with silex, lays hold of the atoms, builds its tiny shells so small that a thousand millions would not make an inch, and patiently, year after year, age after age, piles up the little shells, until five, ten, perhaps fifty feet of infuso- rial earth forms the material for the quartz veins of our continent yet to be. Ten thousand, twenty thou- sand, and sometimes fifty thousand feet of various min-
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HISTORY OF AMADOR COUNTY, CALIFORNIA.
erals may be deposited in this way, all this matter being slowly worn away from some pre-existing land, which perhaps has had a birth in a former cycle. As the material accumulates and acquires depth, the internal heat of the earth, which is manifested in all deep mines, by an increase of temperature of one degree for each sixty feet or thereabouts, begins to facilitate and perhaps produce chemical changes in the first formed strata, which soon lose their former texture and become our future metamorphic, or, as they were formerly called, the hypogene schistose rocks. Allowing an increase of one degree for each sixty feet, we have for a depth of forty thousand feet a heat of six hundred or more degrees, and making allowance for rents and seams permeating the mass, probably much greater in places. And now for some unknown reason, the great mass, so long quiet, slowly arises out of the water, not all at once, but in long, parallel reefs, one preceding the other perhaps by ages; low and marshy at first, but soon, geologieally speaking, assuming shape. Wbeth- er from a greater force of upheaval or from a weak- ness or want of cohesion, some of these ranges, or axes of elevation, break for great distances, and granite is erupted, forming mountains, down whose sides water begins to run, carrying the detritus or decay into the new valleys. The mineral matters, having undergone great changes in the depth of the earth, appear, perhaps, concentrated into veins.
Now, let us consider for a moment the appearance of these different strata. At first horizontal and existing in floors and parallel layers, they are now distorted, bent in places into the shape of a " U," in others into a " V" shape, the lower parts being still down thousands of feet in the earth, subject to the six hundred or more degrees of heat, which were before referred to. If we could see the strata in its shape where the mountain chains are being elevated, it would present an appearance something like a hundred or more layers of cloth pressed edgewise together, thus :-
The reader will not for a moment consider that the different layers of rock will hold together like cloth; we have supposed the breakage to take place where the greatest strain occurred, which would be on the top of the bends or bights. We must also consider these bends, anywhere from ten to twenty miles apart, or at least twice the thickness of our deposit in the sea, though these mountain elevations may be hundreds or even thousands of miles apart, in which case we might have a valley like the space
between the Alleghany and Rocky Mountains, or with unequal elevations, we might have a valley like the space between the Sierra Nevada and Rocky Mountains with short ranges interspersed.
We have presumed upon the tops of these bights or axes of upheaval, breaking so as to expose the lower lying strata. In fact, denudation would set in and the tops of these elevations would be cut off nearly to the line of the primitive or granitic rocks. It is now evident that the lower or first formed rocks, being the hardest or most highly metamor- phosed, would form the tops of the ridges, even where the granite had not cropped out.
The formation of mountain ranges is a thing of past ages, but is a product of forces still in operation. Slowly the Coast Range is emerging from the sea, and along the base of the Sierra Nevada Mountains, as well as the Coast 'Range, are indisputable marks of a former sea-shore, when both ranges of mountains and the intervening valley were some hundreds of feet lower than at present. Ilow manyof these axes of elevation occur in the Sierra Nevadas, may not be determined, but it is quite certain that the higher mountains were, so to speak, in active operation while the foot-hills, where the principal mines are, were still the floor of the ocean. It is also certain that the older or higher ranges had auriferous quartz veins, while the present worked veins were either unformed or slumbering in the depths of the sea. Those who have never studied the rocks, except to learn their economic value, can form but little idea of the history of their creation, which their texture, quality and locality relate. A boy who picks up a rounded quartz pebble considers it a good article with which to pelt a dog or knock a squirrel out of a tree; a gravel miner would consider it an indication of a hill deposit, and forthwith would commence a shaft on the top of the nearest hill; while a railroad man would think a deposit would make splendid material to ballast his road. A geologist would immediately ask, " Where is the river which rounded this pebble ? for every rounded pebble is the result of pluvial action. Where is the quartz vein from which this has been torn ?" A bed of boulders on the top of a hill marks the bed of an ancient river, though the present stream runs some hundred feet below. IIc will tell you that in by-gone ages the river was up there; that the valleys had been made by erosion. So every rock, every pebble, has its history. The placers which were worked in an early day-Tunnel Hill, Butte Basin, Prospect Ilill, American Hill at Oleta, as well as Loafer Hill-all speak of a system of rivers, and of course a system of quartz veins from which the gold was filched. The vast masses of sand, gravel, and clay, with which the San Joaquin valley is filled, as well as the croded valleys, ancient rivers, and lava-capped hills, all testify of the forces that have helped to make our present abode.
A history of the denudation may be read in the layers of potter's clay, gravel, sand, and lava, that
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GEOLOGY OF AMADOR COUNTY.
form the foot-hills and the bed of the San Joaquin valley. The Buena Vista mountain is, perhaps, from its exposure on several sides, a convenient book of reference. Standing on the top of this, one may see many parts of the original plain, of which this mountain formed a part, that once rested on the valleys of Ione, Buena Vista, and Buckeye, from three hundred to six hundred feet thick, sloping to the edge of the former sea-shore, which was forced farther away as the masses of matter carricd down by the rivers filled the valley or basin, precisely as the debris or slickens is now filling up the low places. The top of this mountain is about six hundred feet above the valley, and seems to have formed a part of the same plain which extended east past Jackson, Sutter, and Amador, though at these last-named places the plain was some hundreds of feet higher than at Buena Vista. Marks of this plain can be seen around the base of Butte mountain, which stood, like Thomas H. Benton, " solitary and alone," while the shallow rivers fumed and fretted at its feet, depositing beds of auriferous gravel to be scrambled for in after ages. Let us see what the
BUENA VISTA MOUNTAIN
Is composed of. Commencing at the top, we find indurated volcanic ash, or what may be termed trachyte, with some indi- eations of columnar cleavage 80 feet.
Coarse fragments of lava, not hardened, forming a loose, porous soil. This is the sloping portion, below the bold part of the hill. 100 fcct. Bed of volcanic and quartz gravel, contain- ing some gold 50 feet.
(This, on the surrounding hills, is the bed upon which is generally superimposed the breccia, or unwashed lava, not having been rounded by the action of water.)
Sandstone, resembling granite, suitable for building purposes 40 fect.
(In some of the surrounding hills this becomes of a fine red color, owing to the presence of sesquioxide of iron. The bal- ustrade of the steps of the Court House in Jackson are made of this stone.)
Clays of different kinds, containing, in places, iron ore, sometimes white, some- times composed of sand, white as snow, supposed to be mostly from volcanic material, as in corresponding strata; far- ther west, pieces of pumice-stone of finc quality abound 200 feet.
Carboniferous clays and sandstones, con- taining impressions of vegetation, mostly of the kinds now growing, such as alder, ash, pine, cedar, spruce, with some of leaves resembling the palm. The feathers of birds are also converted into coal, and preserved in the seams of elay 100 feet.
(These clays are the matrices of the coal beds, which vary in thickness from a mere stain to several feet.)
Ferruginous clay, containing spheroidal concretions, from a foot to six feet in diameter, with impressions of leaves and plants. The discovery of an old well, with cut stone walls, proved to be the lower half of a concretion, the shell of which bore much resemblance to a stone wall
40 feet.
Coarse clay and beds of sand, with some vegetable remains half converted to coal. These veins furnish water for the artesian wells; when traced to the mountains they become auriferous gravel-beds (*) ___ 150 feet.
These strata all have a descent to the west of about one hundred feet to the mile, and correspond nearly with the ascending beds of the ancient east and west rivers; thus, continuing the line east at Jackson, the elevation of the plain would be about twelve hundred feet; at Volcano twenty-five hun- dred. This plain terminates in the present Sacra- mento or San Joaquin plain, about five or six miles west. The lava flow may be seen in several places dipping into the ground, or into the level that was once a sea-shore line, as at Whipples, near the Poland House on the Mokelumne river; on the mountain west of J. P. Martin's lower ranch, where it forms the erest of the mountain; on the hills south of the Newton mine, and, perhaps, in a hun- dred other places in the county.
I have deemed it necessary to particularly notice the formation of the foot-hills, because here we have a record of the denudation that has gone on in the mountains, the separate layers each telling its story. Let us examine the lowest formation, which here rests on the hardest and most highly metamorphosed slate we meet with in the whole series of the foot- hills, the slaty structure being very hard to trace. These recfs of rocks form the dividing lines, and frequently, the boundaries of the valleys; as, for instance, the hill near the junction of Dry creek with Jackson creek, and the same class of rocks north and south of Jackson valley. In looking at these one can easily believe they have been a mass of boulders, partially melted and fused together. You can easily pick out roeks of different kinds, which seemed to have formed the original mass, yet the geologists tell us that they were never melted; that this apparent fusion occurred when the rocks were in a plastic state, and that the boulder appear- ance is due to the tendency to spheroidal coneretion, manifested by all plastic substances. The long reefs of rocks, smoothed as if with. a plane, show the wash of a surf for an indefinite period of time, and the subsequent burying by matter, held in suspension, indicates a calm, sheltered bay, where the tides and currents were gentle.
*These figures are in round numbers. The depth or thickness of the strata constantly varies.
₹
1
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HISTORY OF AMADOR COUNTY, CALIFORNIA.
If we examine the gravel at the base of the slate hills, we shall find no volcanic matter ; quartz, slate, and granite boulders only. This would indi- cate a considerable period of erosion, of deundation of the hills before any eruption of lava. The next deposit is mostly destitute of volcanic matter, but coutains much iron, indieating a breaking down of ledges or rocks containing iron and sulphur, as sec- ondary sulphurets are frequeut; in fact, much of the gravel of this age is cemented by sulphurets; for instance, in the lower beds of gravel in Mat Mur- ray's claim, at Lancha Plana.
THIE CARBONIFEROUS CLAYS.
These contain a great deal of volcanic matter which seems to have been carried into the rivers as ashes, pumice-stone and scorie. In many places the pumiec-stone, as in the hills west of Ione, is found in considerable quantities. The streams depos- iting this were apparently running in broad, shallow channels, with but small depression, the layers being regular, and sometimes so thin that hundreds of different deposits may be found in the thickness of a foot. The length of this period seems to have been immense. We ean eoneeive something of the num- ber of years necessary to fill up a valley, even like that of the Sacramento or San Joaquin with running rivers, bankfull of mud, gravel, and sand; but to calculate the time a gentle current, perhaps only discolored with clay, would require to fill an open sea, or bay, a hundred feet or more deep, makes quite a draft on our stock of time. In this deposit we find the coal- beds which seem to be nothing more than masses of drift-wood, of the kinds now growing on the sur- rounding hills, such as cedar, pine, oak, manzanita, and alder, the latter being particularly abundant, inclosed in the tight clays, and imperfectly carbon- ized. This part of the subjeet will be treated more fully under the head of coal.
If a heavy draft on time was necessary for the deposite of the carbonaceous strata, a much heavier one is necessary for the overlying clays, which are, in places, two hundred feet thick. In some places they are alternate with beds of infusorial carth, which could have been deposited only in clear water holding silex, not in suspension, but in solution, as a hundredth, or perhaps a thousandth part of an ineh of mud would have destroyed the insects which build these little shells.
These clays have an economic value. as fine pottery is being made from them, and it is quite probable that poreclain will, at no distant day, be manu- factured, using the elays and quartz of the higher ranges.
GRANITIC SANDSTONE.
There is little voleanie matter in this. The deposit shows a breaking down of granitic rocks, and a more vigorous wash of the streams, indicating an increased altitude of the mountains, and conse- quently a greater carrying power to the water.
BOULDER FORMATION.
For the first time in our record, we find a volcanic boulder iu the drift. The volcanoes now disgorge lava, solid rock, instead of ashes and scoriæ, and are evidently in full operation, the streams being all at work. In many places the lava deposits quite hide the rock-beds heretofore traversed by the streams, as the drift is composed wholly of volcanic boulders which cover thousands of acres, in fact, half the hills of the county seem capped with them. They are hard, almost indestructible, and, wherever a mass has been deposited, effectually protect the ground from erosion.
Breccia, or lava, is found still higher than the boulders, and sometimes has completely filled the channels, turning the rivers into entirely new courses. These masses of lava flowing red hot to the sea, must have presented a magnificent sight to man, if he existed. Boulders of considerable size arc found in the lava, but were probably formed by spheroidal concretion, or by being rolled or crowded along while in a partially melted state. This formed the climax of volcanic action. But for the presence of volcanic ash on the breccia, or lava, we might conclude that the volcanoes ceased their working after the terrific outpour of lava, but it would seem that they quieted down gradually, perhaps were in their old age for centuries. Extensive as the flow was, Amador county was only on the outer edge of the volcanic aetion; farther north the whole country, for thousands of square miles, was covered so deeply that no rivers have cut their way through it. If it buried gold mines, they are still there. This outflow of lava and boulders pushed the shore-line of the bay some seven or eight miles farther out, burying the drift-wood hundreds of feet deep. If we could have seen Amador county at this time, it would have presented the appearance of a vast plain with a few peaks, like the Butte mountain, and a few of the higher points west of the quartz belt, standing above the mass of lava and boulders. It could have had no vegetation, any more than the Modoc lava- bed. What a few acres are now, barren and sterile, the whole county was then. It could have sustained no vegetation. Some of the places are left, especially in the upper parts of the county.
It must not be inferred that a uniform mass of lava covered the county. The same water-shed as now sent its streams to the sea, meandering upon the plain, piling up here gravel and there sand, chang- ing their courses frequently. Nearly all the strata, described in this chapter as belonging to the Buena Vista mountain, thin out as we strike the slates, and many are entirely lost; a few of the more extensive, like the lava boulder and elay formations, have their representatives in the moro elevated parts of the county.
GLACIAL EPOCII.
A new actor comes upon the scene. From being covered with streams of melted lava, flowing in a
LITH, BRITTAN & REY, S.F.
JOHN A. BROWN.
TOMPSON & WEST, OAKLAND.
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GEOLOGY OF AMADOR COUNTY.
fiery stream to the sea, the ice king throws his mantle over it, and claims it for his own. As in all the rest of North America, or at least the northern part of it, the falling snows accumulated thousands · of years, until, compacted into ice, they were miles in depth. There is not room here to prove the glacial theory. One must read it for themselves, or look for its track in our mountain cañons, or on our long sloping plains. They must see, as the anthor has seen, the piles of rock, miles in extent, heaped up by them, and the vast surfaces worn away, smoothed down as with a gigantic plane, which it is; then the track of a glacier will be recognized, as easily as the track of a land-slide. These glaciers reached to the sea-line, though the heaviest work was done towards the summits. These great masses of ice move, slowly it is true, twenty or thirty feet in a year, forcing along everything in their way that is movable. Granite boulders, twenty fect in diameter, are held in the ice as in a vice, and cut their way through lava, through slate, and through granite, leaving the powdered debris to be carried off in the melting stream, in the shape of clay. How long these streams continued is uneer- tain; long enough to erode deep cañons in the hardest rocks. Silver lake is a glacial erosion; for - years it moved down the canon below Silver lake, down the American river, cutting its way with irresistible force; but the glacial epoch had its time, and the ice king slowly surrendered his dominions, retreating up the mountain sides, stubbornly con- testing each foot of ground. At Silver lake, he made a last stand before a complete surrender. The ice could get no farther than the outlet of the lake, and melted at that point. Here were accumulated the broken and worn-out tools, used in the excava- tion, piled up in a great mass across the lower end of the lake. These dams, or piles of rocks, so well known to geologists, are called moraines, and always mark the retreat of a glacier. The outlet of the lake has not yet worn much below the channel, left at the melting of the great mass. Those who are curious enough to examine them, may find several small glaciers, a few acres in extent, around the lake. We may well believe that a mass of ice a couple of miles in depth, forced along by several miles more upon the mountain sides, could scoop out a basin like Silver lake, or even like Tahoe lake, which is also a glacier erosion. The basin of Volcano is also a glacial erosion, the glacier melting and leaving a lake nearly a hundred feet deep, which shrunk away as the waters cut the canon deeper. The limestone, sometimes smoothed as if hammered and polished, and then, again, honey-combed by the streams flowing from the melting mass of ice, have kept a faithful record of the matter. Butte basin is also another glacial erosion, with this difference, however, it was filled up within a short time after the melting of the ice. The long sloping valleys around Jackson, Sutter, Amador, and Plymouth,
have the same origin. As a general thing, a valley with the bed-rock near the surface, worn smoothly away, without regard to the character of the rock, is the result of glacier erosion, as is also a long, straight, or nearly straight, channel of a creek. A crooked channel, dodging the hard places, is a water erosion. The present channels of the streams are below the channels eroded by the glaciers, from one hundred to four hundred feet, so that the track of the glaciers must be looked for on higher ground.
If we could take a section a few miles in depth, out of the mountains between Ione and Volcano, the appearance would be something like the following rough drawing :-
A
B
C
D
We will suppose "A" to be in the vicinity of Ione; " B" to represent the serpentine range which passes the Mountain Spring House; " C" to be the ridge west of Jackson, Sutter Creek, Amador, and Ply- mouth, and " D " to be the ridge west of Volcano and the principal marble range, these points being the axes of elevation, no attempt being made to preserve the relative distances. Further examination might show another axis of elevation between the Mother Lode, as it is called, and the limestone range, but the pres- ent diagram is accurate enough to illustrate the theory of denudation, the mineral veins and the ancient valleys. It will be seen from this that a great portion of the elevation is gone. It may have been, probably was, miles in depth, for the lime- stones that now form such prominent objects in many parts of the county are destitute of fossils, with a high crystalline formation, which changes could have been accomplished only under the pres- sure of a superincumbent mass of perhaps, miles in depth. The same pressure was requisite to obliterate the fossils of the metamorphic rocks constituting the summits of the hills at the axes of the elevations. If any one should object to this as involving too great a removal of earth, a question as to the source of the material forming the San Joaquin and Sacramento valleys might prepare his mind to assent to the denudation.
FORMER COURSE OF THE RIVERS.
The present rivers intersect these ridges or for- mer mountain ranges, yet there are many facts showing a system of rivers running parallel with these lines of elevation. Looking at these mountains in a clear day, from an elevated point on the Sacra- mento plains, one may easily trace the course of these rivers by their banks which have been only partially obliterated. From Bear Mountain in Cala- veras to the ridges west of the lower end of Indian creek, in the northern part of the county, and the 1
17
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HISTORY OF AMADOR COUNTY, CALIFORNIA.
ridges west of the quartz mines of Nashville and Aurum City, the marks of an ancient valley are unmistakable. The other valleys, though not so prominent, may be easily traced. The gravel beds also furnish another incontestible proof of the exist- ence of these valleys. The glacial erosion did not wholly obliterate the beds of the ancient rivers. Beginning with Tunnel hill, where we find a large deposit, we pass northward, passing Jackson, which we find to be in the track of a glacier, to the hills east of the Gate, when we again come upon the river bed. North of the Gate it passes under the lava ridge, shows itself on the east side of the town of Sutter Creek in several places, though it is somewhat obscured where the east and west streams intersect it. An examination of the gravel will generally determine the age of the stream. As the stream we are follow- ing existed previous to the volcanic era, we shall find few or no boulders of that formation. East of Ama- dor and Plymouth the traces are nearly obliterated. Snake Flat, cast of the Gover mine, probably is a relie of the river. East of Volcano we also find the same evidence of former streams. Prospect hill, now overgrown with pines, Humbug hill, and the hills in the vicinity of Spanish gulch, the hills farther up the forks of Sutter Creek, Mason's claim, Hall's claim, the Italian claim,-all belong to that age of deposit. Thestreams must not be confounded with the subsequent rivers which intersected all that we are speaking of. The rivers of the first instance were shallow, meandering along valleys of considerable width, following no certain direction and frequently changing their channels. The quartz boulders abounding in these channels do not indicate a power- ful stream but rather a steady wear; furthermore, the boulders, especially the heavy ones, were not moved far from the veins, which usually may be found within a short distance. Itis highly probable that the actual elevation of these rivers was much less than at present. Perhaps at this time a description of the great lead of California may be introduced as showing the character of the rivers existing previous to the volcanic era. This description is taken from the Overland Monthly, and is worthy the attention of all desirous of a knowledge of the former systems of rivers. We propose to show in a future chapter the possible continuation of the river into this county, all traces of it having been, according to our best authorities, lost.
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