450 SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION. 
the road. At first sight it appears to be a mass of slate rock ; but upon inspection it proves to 
possess a highly crystalline structure. : 
The Go-ahead shaft was sunk several years ago. It is said to have reached gravel and bed-rock | 
at a depth of 352 feet, when further operations were suspended on account of the great influx of 
water. The surface works can still be seen a little to the northwest of the road. I did not stop 
to go to the mouth of the shaft, but made its altitude to be approximately 5,450 feet. If the » 
above-mentioned depth of the shaft is correctly given, the bed-rock has an altitude of only 5,100 
feet, hardly twenty-five feet higher than the bed-rock at the upper end of the La Porte mines, 
though a little more than two hundred feet higher than that at Claybank. Compared with the 
bed-rock at Gibsonville, the altitude of which I made to be 5,420 feet (estimating at eighty feet 
the difference between it and the hotel), there is a fall of 320 feet within a distance of but little, 
if any, overa mile. Either the statements made about the Go-ahead shaft are incorrect, or there 
is here a fresh puzzle to be solved by further surveys. 
The Gibsonville sub-district embraces a region about three miles in length on the right bank of 
the northerly fork of Slate Creek, between the ereek and the high lava ridge already mentioned as 
extending from La Porte to Pilot Peak. The lower portion of this district is shown on the map 
(Plate T), which is a reduced copy of a manuscript map made by Mr. Hendel in 1876. The crest 
of the lava ridge is from six to nine hundred feet above the hotel at Gibsonville, the altitude of 
which I made to be 5,500 feet. A part of the gravel is covered by the volcanic material, and has 
been worked by drifting only. Where the gravel is not so covered, the hydraulic process has been 
used to some extent ; but lack of water has prevented its general adoption, and drifting has been a 
necessity. With increased facilities for obtaining a supply of water, some of the banks from which 
the lower stratum has already been removed will ultimately be washed away. 
The old custom used to be to lay out claims four hundred feet wide in front, and extend them 
back to the centre of the ridge. The tunnels were usually driven from 2,000 to 2,500 feet be- 
fore the back rim was struck. The following list comprises the most important of the claims in 
this vicinity, beginning with those near Gibsonville: Chalcedonia, Boot-jack, Wild Boar, Blue, 
Sierra, Enterprise, Mount Pleasant, Ditch Company, Union, Nip and Tuck, Michigan, Nevada, 
Goodshaw, Swiftsure (at Whiskey Diggings), Kepner and Johnson, Washington, Redding, Gem, 
Phoenix, New York, Niagara Consolidated (including several different claims near Hepsidam, the 
point farthest to the northeast from Gibsonville and near the base of Pilot Peak). I have omitted 
the most of these names from the map (Plate T), for lack of time to ascertain the precise positions 
of the several claims. 
There was no work doing in the hydraulic mines at the time of my visit. Even those which 
can command a supply of water are able to run only for from four to six months in the year, be- 
ginning usually in the month of February. During the fall and éarly winter work has to be 
suspended. There was also little or nothing doing in any of the drift mines, with the exception 
of the Niagara. Many of these mines, indeed, were worked out several years ago. It did not 
seem worth while to make the attempt to gather information — uncertain at best — about these 
old workings, nor to try to get access to tunnels in which work had heen stopped. The most im- 
portant of my observations were made at the Mount Pleasant hydraulic mine, where I was hos- 
pitably treated by Mr. F. A. Gourley, and at the Niagara drift mine, through which I was taken 
by the superintendent, Mr. Miles Schofield. ; 
At Mount Pleasant a tunnel was started about twenty years ago, and drift mining was carried on 
for eight or ten years. Since the introduction of the hydraulic process about ten acres of bed-rock 
have been uncovered. The bank where highest shows at bottom a stratum of blue cement, four 
feet in thickness, above which come six or eight feet of red cement, and about eighty feet of clean 
quartz gravel. 
The property of the Niagara Consolidated Company is at the head of the north fork of Slate 
Creek, and extends back to the crest of the ridge which connects the high point called Bunker Hill 
with Pilot Peak. It comprises over four hundred acres of mining ground, about one tenth of which 
