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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 

 Paver, 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 materia] 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 thai, 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. 



