^m 





^^^^■M 



IMMMHHPiPlimi 



THE GRAVEL: EL DORADO COUNTY. 



101 



adding much to the expense of working the claim. One of these blocks was found, on measure- 

 ment, to be fifty-live feet in length, and to be equal in dimensions to a cube of thirty feet, and was 

 estimated to weigh 2,000 tons. 



At the Henderson Claim, on the north side of Negro Hill, a little northeast of the Oldfield, there 

 have been two or three acres washed off, the maximum height of the bank being 115 to 120 feet. 

 The amount of metamorphic gravel here is very small, and it forms a stratum of a few feet in 



thickness upon the bed-rock. The great mass of the bank consists of beds of volcanic sands and 

 gravels. These are beautifully stratified in horizontal layers, and much of the material is very 

 thinly and delicately bedded. This ground is said to be very rich in gold. 



The maximum depth of the gravel, including the " mountain gravel," at Indian Hill, is about 

 sixty or seventy feet ; and there are five or six acres over which the average depth is twenty feet. 

 On the top is a thin capping of "black lava," perhaps from three to four feet in thickness, — not 

 enough to give any serious trouble in hydraulicking. 



At the southwest end of Clay Hill, a little southwest of Indian Hill, there has been a quarter of 

 an acre of ground washed off, exposing a hank twenty-five to thirty feet high, of which the lower five 

 or six feet consist of quartz and metamorphic gravel, generally rather fine : all the upper portion 

 is a coarse "mountain gravel," occasionally containing very large and very smoothly rounded 

 boulders ; one of them was found to be not less than ten feet in diameter and nearly spherical in 



shape. 



At the west end of Indian Hill, a little to the northeast of Clay Hill, a considerable extent of 

 ground has been worked, showing the face of a bank from twenty to thirty feet high, for a couple 

 of hundred feet in length. Only a thin layer on the bed-rock here could have been of metamorphic 

 material, for the whole face now visible is volcanic. The lower portion consists, to a great extent, 

 of gray volcanic sand, with occasional thin layers of fine " mountain gravel." The upper portion 

 of the bank consists entirely of coarser mountain gravel; and the structure of the bank shows, that 

 after the sand had been deposited, it was again here and there channelled out to a greater or less 

 extent, before the mountain gravel was laid in heavier masses over it. 



At the Sugar Loaf, a hill on the south side of Webber Creek and about a mile below Diamond 

 Springs, an area about 800 feet long and 200 wide was first drifted out, and has since then been 

 washed off, so as to have, removed the whole original top of the hill. The gravel which averaged 

 about fifty feet in thickness, and was not capped at all with volcanic materials, was metamorphic, 

 well- washed, and contained a, good many quartz pebbles, but no large boulders, stones of more 

 than a hundred pounds' weight being rare. Most of the pebbles which were not of quartz were 

 thoroughly decomposed, and the mass of tailings slacks quickly on exposure to the air. The total 

 yield of this deposit was, it is said, not far from $ 3,000,000. 



On the east side of Lean Hill, just northeast of the Sugar Loaf, at Diamond Springs, the bank 

 exposed is about 1,200 feet long, and ranges from twenty to forty feet in height. About four or 

 five acres of ground have been washed off here, with an average depth of about twenty feet. The 

 gravel is mainly metamorphic, yet containing a good many boulders of "white lava" and occasion- 

 ally of other volcanic materials. Nearly all the pebbles, except those of quartz, are much decom- 

 posed, so that the bank washes very easily. 



In the Deadhead Claim, three quarters of a, mile below Newtown, on the south side of Webber 

 Creek, an area has been washed off estimated at about 800 feet long by 200 feet wide, with an 

 average depth of 30 feet. The gravel here is chiefly metamorphic, but contains a good many volcanic 

 boulders, a large proportion of which are "white lava," scattered throughout its mass, and also 

 many boulders of a rock of granitoid texture, but consisting of quartz and feldspar without any ap- 

 preciable quantity of mica. 



At Brownsville, on the North Cedar Creek, the gravel in the front of the claims is said to have 

 been seventy feet thick, at least, above the bottom of the workings, the bed-rock not being reached. 

 ■The gravel grew thinner as they went into the hill, its upper surface sloping to the south. It was 

 almost exclusively a quartz gravel, the pebbles being rarely very large. 



I 





■ ■ 



! 1 1 



■ 





^^H 



^h 





L 



■ 





1 





^t^Hl 









