

r*^H 



CHARACTER OF THE GEAVEL; PLACER COUNTY. 



91 



gravel ; this is generally yellowish-white in color, and not very strongly cemented together, the 

 boulders and pebbles of which it is composed being entirely quartzose and metainorphic in char- 

 acter, without any granite or volcanic. They are also generally rather small, few being larger 

 than a man's head, and not usually exceeding the size of the fist, although occasionally boulders 

 weighing several hundred pounds may be observed. The body of the gravel is generally very 

 nearly horizontally stratified. But near the bed-rock there are occasional appearances of cross- 

 stratification, or " beach-structure." In one place an inclination of the layers as great as 15° was 

 observed. The thin streaks of sand occurring here are generally of limited extent, irregular in 

 shape, forming lenticular patches in the gravel, often bifurcating with it and entirely surrounded 

 by it, and varying in thickness from a few inches to several feet. 



At Independence Hill, a little northwest of Iowa Hill, in the Reno Claim, the thickness of the 

 auriferous gravel is from 75 to 100 feet. 



In the Morning Star Tunnel (near Iowa Hill) the gravel is what is called " blue cement," the 

 pebbles being all metainorphic, often very hard, and consisting to a great extent of a dark-blue 

 sandstone and slate, with less quartz than at Iowa Hill. 



At the head of Refuge Canon just west of the Wisconsin Hill school-house, some sluicing has 

 been done, and banks of gravel twenty-five or thirty feet high are exposed. There are some very 

 large quartz boulders here. This work is said to have yielded in a short time over $10,000. 



A few hundred feet east of Mr. Teasland's house at Wisconsin Hill a shaft was sunk through 

 gravel, said to be 190 feet deep, without reaching bed-rock. 



In the Lebanon Tunnel, on the northeast side of New York Canon, an air-shaft was raised to the 

 surface giving the following section. 





Volcanic conglomerate 

 Auriferous gravel 

 Vol canic conglomerate 



Auriferous gravel . 

 Bed-rock , . , 



Feet. 



90 

 4 



160 



60 

 40 



At Nahor's Claim, in Green Valley Gorge, the layer of gravel resting on the bed-rock is quite 

 thin, more or less mixed with volcanic boulders, and covered over, first with more or less volcanic 

 conglomerate, and then with a heavy mass of volcanic breccia. 



At Sucker Flat, where a tunnel was driven on the surface of the bed-rock, N. 45° W. magnetic, 

 some 1,300 or 1,400 feet into the hill, the quantity of gravel was very small, and it was imme- 

 diately overlaid by heavy masses of volcanic debris. But very little gold was found. 



At the Cement Knob Mine, in the spur west of Grizzly Canon, and about a mile below Grizzly 

 Flat, the layer of gravel is said to vary from six to eighteen inches or two feet in thickness, and 

 it is overlain by volcanic materials. 



The gravel in the Mountain Gate Tunnel, at Damascus, is all white in color, except that in some 

 places it is stained slightly red with oxide of iron, the pebbles and boulders consisting entirely of 

 quartz, which is remarkably uniform in character, compact, white and solid, and only occasionally 

 a little crystalline. Some of the quartz boulders are very large, weighing, it is said, a hundred 

 tons or more. But these largo boulders seem to occur only near the bed-rock ; and the gravid 

 grows rapidly liner on going upward from it. The material between the boulders and pebbles 

 consists largely also of quartz sand, mixed, however, to some extent with clay derived from the 

 disintegration of the slates. The gravel is generally not very hard, except occasionally near the 

 bed-rock, where it contains much iron pyrites. 



On the east side, of Damascus Canon, and one eighth of a mile from the hotel, there is a 

 hydraulic pit exposing a bank with from forty to fifty feet of gravel, covered by from twenty to 

 twenty-live fed, of water-washed volcanic gravel. The gravel here is very much like that in the 



Mountain Gate Mine, being white below, with plenty of large boulders near the bed-rock, growing 



liner above and assuming a yellowish tinge, sometimes deepened into red by oxide of iron. At 



