456 SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION, 
noticed, is eight feet dower than the bed-rock at Portwine. The measurement at Portwine was 
made, it is true, upon the western rim, but it would be reasonable to expect the altitude, even high 
up on the rim, to be less than that of the deep bed-rock at Gardner’s Point. Without any knowl- 
edye of the intermediate channel, the actual condition of things would be quite difficult of expla- 
nation. A partial if not a complete key to the difficulty is said to be found in the old “ Monte 
Cristo slope,” a drift mine about three quarters of a mile above Portwine. I could not examine 
the mine in person, and shall have to record hearsay testimony as to what was observed there when 
the mine was worked, several years ago. The coarse pay-streak, which the miners were following 
on bed-rock, with a steady rise from the direction of Portwine, suddenly changed to a fine gravel, 
poor in gold. The bed-rock as suddenly dropped over fifty feet. The wall of rock, overhanging 
to the north, was smooth and polished, showing a slickensides surface. At the lower level the 
pay-streak was again struck, and followed upon a rising grade for 500 feet, the gravel and water 
being all hoisted over the ledge of rock. This description, illustrated in the diagram (Plate 8, 
Fig. 5), can refer to nothing else than a fault in the strata, of a date more recent than the deposi- 
tion of the gravel. 
It will not be worth while to attempt to enumerate the different mining claims which have been 
worked or laid out along this part of the ridge. The positions of nearly twenty such claims, within 
a distance of a little more than a mile, are given on Mr. Hendel’s map of the Pioneer Company’s 
ground. As a result of this extensive drifting, the richer parts of the gravel have been, to a large 
extent, removed. What remains would probably yield well, if water for hydraulic mining could be 
obtained at a low rate and in sufficient quantity. The most of the water at present obtainable from 
Slate Creek is used at Pine Grove, but there seems to be no good reason why some of this water, 
if not all, may not be used over again at the lower mines. To bring water from Caiion Creek or 
from the sources of Feather River will require the construction of more expensive ditches and 
tunnels. Considerable work has been done with this end in view, for the sake of washing a large 
body of untouched gravel at Grass Flat. At the last-mentioned place I visited, in company with 
Colonel B. F. Baker and Mr. G. W. Cox of Pine Grove, the large, unfinished sluice-tunnel in bed- 
rock, and the upper prospecting tunnel in gravel. Since the death of Mr. Ralston, who was one of 
the principal owners of the property, all work has been suspended. There is some prospect, how- 
ever, of the resumption of operations at an early day. My examination of this deposit was not 
sufficiently minute to justify my making any estimate of the amount of gravel left to be washed, 
or of its probable yield of gold. I was told by Colonel Baker that the gravel in the prospecting 
tunnel, though from twenty-two to thirty feet above bed-rock, yielded at the rate of one dollar per 
cubic yard, and that, by the sinking of a shaft, the gravel has been proved to be one hundred feet 
in thickness. It is also claimed that the channel, where it crosses Grass Flat, is 1,400 feet wide. 
Hydraulic mining at Gardner’s Point, where the average thickness of gravel worked was between 
twenty and thirty feet, has exposed to view an overflow of volcanic material, a thousand feet or 
more in width, which in some places has cut away the gravel to within four feet of the bed-rock. 
The gravel is a clean white quartz, with the exception of two or three feet in thickness of an iron 
cement upon the rim. There are no large boulders, and there is but little pipe-clay, though more 
may be expected as the bank is washed farther back. The gold is said to resemble flax-seed, 
never being found in large nuggets. It was here that Colonel Baker, in 1872, found a diamond, 
which, when cut, weighed a carat. Perhaps the small rough diamond in Mr. Hendel’s possession, 
found in the Slate Creek tailings, also came from this point. 
Between Gardner’s Point and St. Louis there is a high bed-rock spur, which must have thrown 
the old channel to the west. Yankee Hill, a small deposit of gravel on the right bank of Slate 
Creek, has an altitude, as estimated by sighting across the caiion with the hand-level, a little higher 
than that of Gardner’s Point. I did not go to Yankee Hill, but it is evident that its gravel 
belongs to the St. Louis channel, and has no connection with the channel from Gibsonville. 
To reach St. Louis from Gardner’s Point, Cedar Grove Ravine has to be crossed. Near this 
crossing there niust have been at one time a junction of a tributary from the northeast with the 
