208 “THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 
channel for several miles, and the west branch of the same taking up and 
continuing the parallelism for many miles, keeping almost the same direction 
as far as the great volcanic flow which extends to the south-southeast from 
Lassen’s Peak, in the region where the Butte County Table Mountain proba- 
bly heads. 
According to Mr. Waldeyer’s notes,* the gravel under this lava flow is 
extremely thick, being nearly equal to its greatest development on the 
divide between the Yubas. The bottom gravel is, as usual, of a bluish color 
and cemented together. The pay streak is said to be only a few feet in 
thickness, and the finer material above, mostly quartzose sand, is poor, al- 
though not destitute of gold. The basaltic capping is from eighty to a hun- 
dred feet in thickness. The gold in the gravel is often found in nuggets of 
considerable size. 
The peculiar position of this locality —so low down in the valley and so 
isolated as it is— has rendered it a matter of difficulty and great expense to 
procure the necessary amount of water for carrying on hydraulic mining here 
on a scale suitable to the magnitude of the deposits. The principal works 
are at Cherokee Flat and Morris’s Ravine. At the first-named locality the 
Spring Valley Canal and Mining Company is engaged in operations on a 
scale almost or quite unprecedented, even in California. The water used by 
this company is brought by two ditches, sixty miles in length, from Butte 
Creek and the head waters of the West Fork of the Feather.t The product 
of gold here is said to be very large, and the profits considerable. At Mor- 
ris’s Ravine, a few miles north of Cherokee, there has been a heavy expendi- 
ture required to bring in water and for other necessary preparations for wash- 
ing on a grand scale. 
§ 3. The Region North of the Middle Yuba. 
The Middle Yuba River forms the boundary between Nevada and Sierra 
counties, and the hydraulic mines described in the first section of this sub- 
division of the detailed geology of the gravel districts belong to the first- 
named of those counties ; those between Oroville and Dogtown are in Butte, 
and the mines now to be briefly noticed extend across the west portion of 
Sierra into the centre of Plumas County. 
* Published in the Fifth Report of the Commissioner of Mining Statistics, p. 72. 
t Mr. Waldeyer puts down the expenditure at Cherokee in improvements, up to 1873, at $ 1,305,000. 
