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LITTLE GRASS VALLEY AND VICINITY. 469 
There has not been work enough done to prove the existence of any large body of gravel. A 
tunnel seventy feet in length has been driven, showing that the gravel is continuous for that dis- 
tance, and that the bed-rock pitches to the southeast ; that is, towards the centre of the ridge. 
Messrs. Gard and Makins, to whom I am under obligations for a very hospitable reception, were 
about bringing water in for the commencement of hydraulic operations at the time I was there. 
The gravel, when exposed to view, is composed of small, rounded quartz pebbles, together with 
some thin sandy layers, and thin clay seams with impressions of leaves. ‘These were too fragile 
for preservation. Charred wood is also found. The gold is said to be coarse, resembling flax-seed. 
There is no scaly gold. The altitude of the mouth of a shaft, said to have been sunk in 1857 to 
a depth of fifty feet through pipe-clay and sand to bed-rock, I made to be 4,900 feet. 
The gravel at Post’s claim in Wilson’s ravine presents some features of extraordinary interest. 
The claim lies a few hundred feet back from the South Fork of the Feather River, and about 150 
feet above the bed of the stream. The altitude of the bed-rock at the mouth of the tunnel I made 
to be 4,425 feet, — nearly 400 feet lower, it will be observed, than that of the bed-rock at Davis 
Point, on the opposite side of the ridge. The tunnel has been driven for 200 feet in a north- 
westerly direction ; but, as the bed-rock pitches also in that direction, the accumulation of water 
prevents any further prosecution of the work without the use of pumping machinery. Lateral 
breasts have been driven from the tunnel sufficient to indicate a width of 200 feet of gravel. High 
bed-rock exposures are seen both to the north and the south of the gravel. The bed-rock in the 
tunnel shows many signs of wear. ‘The thickness of the gravel has been proved to be as much as 
twenty feet in some places. Above the gravel there is pipe-clay, and the surface of the ridge above 
the deposit is covered with gray lava. The composition of the gravel is widely different from that 
of any other deposit that I saw anywhere else in this vicinity. In addition to the ordinary fine 
white and blue quartz with some large boulders, there are several varieties of bed-rock represented, 
such as metamorphic slate and granite. The pebbles are all well washed and rounded though 
those composed of bed-rock are much decomposed. Bunches of micaceous sand are quite frequent. 
But the most striking and unusual occurrence is that of rolled pebbles of basaltic rock. To avoid 
all error of field observation, I picked from the gravel near the farther end of the tunnel a few 
small pebbles of this character, — such as could be easily brought away in the pocket, — and put 
them into Mr. Wadsworth’s hands for microscopic examination. He describes them as basaltic 
rock which has undergone some decomposition, — as might be expected when the circumstances 
under which the pebbles are found are taken into consideration. Among the pebbles there are 
also some which look as if they came from some previously existing gravel bed. The gold in this 
gravel is fine and scaly. 
The facts above presented lead irresistibly to the conclusion that the gravel in this deposit is 
geologically younger than that of La Porte and other mining towns on the Yuba slope of the 
divide. My information is too meagre to justify my hazarding any theory as to the origin of this 
deposit or its relations to others. There is, however, something very plausible in Mr. Post’s belief 
that it has some connection with a deep channel crossing the ridge in a northwesterly direction, 
and now filled with gray lava. The position of the lava, as above described, in the bed of Fall 
River, and its altitude, lend some support to this belief. In this connection I will add (on Mr. 
Post’s authority, not from personal observation) that there are also other gravel deposits, not far 
distant from this one, but at a higher altitude, in which the gravelly material is quartz and bed- 
rock with no basalt, in which the gold is thick and heavy, and upon which a basaltic capping 
rests. I regret that I was unable to make any further study of so promising a region. 
At the Monitor shaft, previously alluded to, bed-rock has been reached since the date of my 
visit, at a depth of fifty-two feet from the surface. For the first eight feet the shaft was in the 
common surface dirt ; the rest of the distance was in gravel. Charred wood was found ten feet 
from the bottom of the shaft. From what I saw and could learn about the explorations at this 
point, I was led to conclude that the deposit is one of very limited extent, and of purely local 
interest, without any connection with any larger body of gravel. 
