274 GEOLOGY. 
at the Swiftsure Tunnel, and also containing forest trees. Above this compact clay, however, 
there is a ** cement,” or mixture of clay, with volcanic ejections similar to that at Mameluke 
Hill. A thin trap-dyke was observed traversing the slates. 
This claim has yielded great profits to the proprietors. At one place, where the lead was 
first struck, one hundred ounces of gold were taken out from a space eighteen feet long and six 
wide. The gold lies close to the rock, and in places has penetrated between the layers of slate 
to the depth of a foot or more. It is enveloped in a thin layer of very firm blue clay, derived, 
to all appearance, from the abrasion of the slate. 
The gold could be seen thickly implanted in this clay and on the surfaces of the layers of slate 
from six to eight inches or more below the general surface of the bed-rock. One pan of the 
clay was taken from one of the richest spots and washed out before me. It yielded about six 
ounces, ór one hundred dollars’ worth of beautiful gold, all of it in large scales. The sluice had 
been in operation half a day, washing out the ‘‘pay-dirt’’ collected by two men in the drifts. 
This operation issery interesting. The gold having accumulated among heavy pebbles and black- 
sand along the course of the sluice, is to be collected together or ‘‘cleaned up.” It is accomplished 
by taking out the bars and turning on a greater quantity of water, thus increasing the force 
and velocity of the current. The supply of auriferous earth being stopped, the current of water 
soon becomes perfectly clear and the bottom of the sluice is distinctly visible. Stones and gravel 
are swept along, but a line of glittering scales of gold appears behind them, and as the gravel 
passes down before the stream the gold follows, increasing in quantity for every foot of its pro- 
gress, until at last it forms a bar of golden grains which may be measured by the pint or pound 
rather than by ounces. ; 
Mr. Currier. presented me with a sample of iron pyrites which is obtained from the washings 
near Georgetown. It occurs in minute and very brilliant cubes all of the same size, and is 
abundant. I also obtained a small mass looking like lead and galena, which, on examination, 
proves to be a telluret of silver. * A crystal of IImenite was also presented to me. 
An outcrop of serpentinoid rock is found about half a mile east of Georgetown, and it appears 
to form a dyke traversing the slates. Further east, a granitic rock appears, but is only visible 
in loose blocks. The soil at this point contains a large amount of peroxide of iron, and it is 
probably auriferous. There are indications of quartz veins between the granite and the serpen- 
tinoid rock. — ' 
VOLCANOVILLE. 
Volcanoville is on the Middle Fork of the American River opposite Forest Hill, and is chiefly 
remarkable for the occurrence of a very interesting vein of auriferous quartz. "This vein outcrops 
in Quartz Cañon, which leads into Otter Creek. The vein, in one place, is three feet thick, and 
trends N. 30? W., with an easterly dip of 45?. Itis bounded on one side by a trappean rock with 
serpentine beyond, and on the other by slate. This slate is on the east side, and is traversed 
by many small veins or strings of quartz, which are also auriferous. The richest part of the 
vein is said to be covered up by earth, but gold is visible in many places in the white quartz, 
and on the wall where the quartz has been broken out. This wall has the usual appearance of 
smooth furrows called slickensides, but not produced by the attrition of the walls. A large 
amount of the quartz is free from gold, and would be difficult to crush. The gold is apparently 
very unevenly distributed, and forms isolated nests and bunches. At » Taylor's Claim," higher 
! See Chapter XX., under Hessite. 
