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rock outcrops occur. The Thistle hydraulic gold mine, on the south side
of the lake, is of special interest as one of the few important discoveries
since the early days, and because the pay-streak is interglacial in age—
that is, the pay-gravels are overlain and underlain by boulder clay deposited
by glaciers. Other occurrences of somewhat similar character are known
in the district, but none in which the pay-streak is so rich as it was at the
Thistle mine.

Placer gold was discovered at Eightmile lake in 1897 by Pat McKenna
and Billie Ogden, who ground-sluiced and hydraulicked on a small scale
for two seasons. The property was then optioned to the Sutherland
Hydraulic Mining Company, Limited, of which B. A. Lasell was manager.
Water for hydraulicking on a large scale was brought by a ditch, 4 miles
long, from Stewart creek, flowing into Valley creek from the south. In
1901 the property was acquired by the Thistle Gold Company, Limited,
of which R. Hannah, of Minneapolis, was president and principal owner.
James Ross, now one of the owners and operators of the mine, was man-
ager. The company also purchased the Coffee Creek mining interests.
From that creek and from other small streams along the side of Big valley
they increased their water supply. Coffee creek lies between Stewart
creek and Eightmile lake. Both creeks are outside the area included in
Map 2046. An hydraulic plant was installed on Coffee creek in 1901
and hydraulicking was carried on for a few weeks during the freshet for
three seasons. At other times all the water available—an average head of
about 100 feet— was used at the Thistle pit. Water was available for two
No. 2 monitors with 3-inch nozzles, for sixty to one hundred and fifteen
full days in the year, the average being about ninety days. In nine seasons
about 360,000 yards of ground were mined. The gold production is said
to have amounted to nearly $375,000. About ten men were employed,
on the average, during the hydraulic season only. The flow of water used
in hydraulicking was approximately 240 miner’s inches and the average
duty of a miner’s inch was about 1-8 cubic yards per 24 hours.

Hydraulicking started near the lake shore, and as the cut was extended
upstream it was found that the grade of the channel was very low. The
sluice flume was laid on a grade of only 4 inches to the box, and it was
difficult to dispose of the tailings. In 1904 a cut, about 500 feet long,
made at the outlet of the lake, lowered it about 4 feet. Mr. Ross, to whom
the writer is indebted for information regarding the property, states that,
after this lowering, bedrock could be seen in the bottom over a considerable
part of the lake near the lower end. The lake was originally about 40 feet
deep in the deepest part, but has been largely filled by tailings. In 1909
an hydraulic elevator was used at the head of the pit where the bank is
steep and about 50 feet high, for the inclination of the pay-streak was so
low that it could no longer be reached by hydraulicking, but the elevator
proved a failure. There was about 40 feet of boulder clay at the top in
the bank at the head of the pit and it was found necessary to break it up
by bank blasts, in two of which several thousand pounds of powder were
used. It was then proposed to mine the ground beyond the head of the
pit by drifting. A tunnel (Figure 20) was run for about 100 feet into the
bank at the head of the pit. A drive was run from the end and struck

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