

BED-ROCK: AMADOR COUNTY. 



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masses. There are streaks and patches of slates and sandstones connected with the granite, making 

 it a difficult problem to unravel the geology in this region. At Brownsville, there is a belt of lime- 

 stone, the surface of which is worn into all sorts of fantastic forms; this rock cannot be traced for 

 any considerable distance, and is apparently not more than a few hundred feet in width. The same 

 limestone occurs again at Indian Diggings, on Indian Creek, where there appear to be several thin 

 belts or patches of this rock. Many of the lingo fantastic blocks into which the limestone lias been 

 eroded, or weathered, have been broken off and rolled down into the Creek below, so that it is 

 difficult to say when the rock is in place and when not. At the last-mentioned locality the bed- 

 rock, when not limestone, is slate and sandstone, all thoroughly decomposed and soft. This de- 

 composed material lias belts, patches, and bunches in it through which is distributed a certain 

 quantity of rolled pebbles of quartz and other rock, the whole forming a curious pot-pourri of decom- 

 posed bed-rock and gravel. There are portions of the rock in which no water-worn pebbles are 

 found ; but in other places there is a great abundance of them scattered about in an irregular way. 

 Some of the belts in which they occur are but a few feet wide, and stand nearly vertical; others 

 are more or loss inclined ; others horizontal, or nearly so, while some are quite irregular in posi- 

 tion. It is said that whenever these rolled pebbles are found distributed through the rock, the latter 

 contains gold enough to pay for washing; and that, when they do not occur, this is not the case. 

 It appears probable that, as the creek slowly cut its way down through the soft bed-rock, tin v re took 

 place, from time to time, a great deal of sliding of the ground ; and that the gravel, which once 

 overlaid the surface of the bed-rock, has thus become irregularly incorporated with its soft mass. 



The most common direction of the strike of the slates in the immediate vicinity of Volcano is 

 northeast and southwest. At the head of the Flat the slate strikes northeast ; though at the 

 foot, just below the town, it runs about north. These rocks arc not unfrequently much contorted ; 

 and the outlines of the limestone masses occurring here arc very irregular. In the canon of Sutter 

 Creek, a little way below Volcano, there is a large quantity of well-characterized talcoso slate, 

 called " soap-stone " by the miners ; but there are also considerable bodies of very hard, line 

 grained, nearly black silicious rock, which is very tough and massive. Limestone forms the bot- 

 toms of all the workings in Indian, Jackass, and Soldier's Gulches, near Volcano; and it also 

 makes up the lower portion of the spurs which separate these gulches. The surface of this rock, 

 especially in the spur between Indian and Clapboard Gulches, is worn out into holes and cavern- 

 ous places of the utmost irregularity of form, with fantastic pinnacles between them. These 

 cavities are filled with gravel, and are often as much as forty or fifty feet in depth. The Hat which 

 stretches along Sutter Creek, above Volcano, is from 500 to GOO feet in width, and, for 

 nearly its whole length, it lias been extensively worked by sinking pits, raising the gravel by 

 derricks, with whims driven by horse-power, and washing it in sluices. These pits have been 

 worked down, sometimes, to a depth of forty or fifty feet, over a width of from 300 to 400. The 

 surface consists of a dark-colored soil, from three to eight feet in depth, and beneath this lies the 

 gravel, the general level of which rises but a few feet above the average level of the higher por- 

 tions of the limestone, whose surface, as in other localities, is worn into the most fantastically 

 shaped cavities. As Mr. Goodyear remarks, " No words can paint the raggedness of these 

 excavations."* Similar phenomena may be observed on the right bank of the South Fork of 

 Sutter Creek, near Aqueduct City, about six miles southwest of Volcano ; at this point a considera- 

 ble area of the limestone has been worked off, or uncovered by mining. The rock here, as in sev- 

 eral other portions of the limestone belt, is intersected by numerous dykes of diorite, which traverse 

 it in an easterly and westerly direction. These dykes vary from two to thirty feet in width ; 

 some are even wider than thirty feet. On the right bank and near the mouth of Soldier's Gulch, at 

 Volcano, there is a locality of complex forms of chalcedony. Close by it there is a rocky point con- 

 sisting entirely of a perfectly honey-combed mass of thin, flat sheets of chalcedonic and jaspery 

 quartz. This rocky knob is- from thirty to forty feet in height, and about the same in diameter. 



* The claim at the upper end of Volcano Flat, where the limestone has the most ragged appearance, is 

 called the " Upper Engine Claim." 



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