CHARACTER OF THE GRAVEL: 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 metamorphic 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 metamorphic, 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 Caiion 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 shafi 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 Caiion, an air-shaft was raised to the 
surface giving the following section. 
Feet. 
Volcanic conglomerate ; pi . : s a ; 2 : ; : 90 
Auriferous gravel. : ° . ° : ; : ; ° : ° + 
Volcanic conglomerate F ‘ ; : : : ‘ : : é «> £60 
Auriferous gravel. = : : : : : ‘ . ; ; : 60 
Bed-rock : ‘ E t ; : : : ‘ ‘ - : , 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 débris. But very little gold was found. 
At the Cement Knob Mine, in the spur west of Grizzly Caiion, 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 large boulders seem to occur only near the bed-rock ; and the gravel 
grows rapidly finer 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 Cafion, 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-five feet 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 
finer above and assuming a yellowish tinge, sometimes deepened into red by oxide of iron. At 
