BETWEEN NORTH BLOOMFIELD AND EUREKA. 405 
for the remaining 800 feet. The tunnel was driven for the sake of opening a drift mine, not for 
hydraulic sluices. At a distance of 523 feet from the mouth of the tunnel a rise was made, and 
gravel was struck seventy feet above the tunnel. At 500 feet farther in gravel was found only 
seven feet above the top of the tunnel, and this distance seemed to remain nearly constant to the 
end of the tunnel. Some drifting was done in blue gravel mixed with large smooth bou!ders, 
for a few months, but for some reason the work has been discuntinued. The bed-rock was flat 
and level. 
The only other places at which I took observations for altitude were at Mr. Penrose’s house and 
at the mouth of an old shaft in the Eagle claim, where it was said to be sixty feet to bed-rock. 
If this last statement be true, the bed-rock in the Eagle ground is fifteen feet lower than the mouth 
of the Great Eastern tunnel, the altitude at the mouth of the shaft being made to be 3,758 feet, 
and about fifty feet lower than the bed-rock at the farther extremity of the tunnel. So far as 
these observations have-any value, they point to a probable course of the stream at this point more 
northerly than I had supposed, if it has a fall in the general direction of Bloomfield, or the Derbec 
Shaft, as is more likely the case. Any alternative supposition, which would select a more southerly 
course for the channel and make it sweep around more nearly parallel to the course of the present 
South Yuba, will have to be excluded, both on account of the topographical features of the country 
and on account of the great difference of altitude between Relief Hill and Bloomfield. If the 
gravel at the Derbec Shaft be supposed to be on the continuation of the channel from Relief Hill, 
the grade between the two places will be but little more than the average grade of the old stream 
for its whole length from Snow’ Point to Timbuctoo. The precise distance from Relief Hili to the 
Derbec Shaft cannot be given, but it will not exceed three miles nor fall much below it. The 
difference of level of bed-rock between those points I make to be 345 feet, —say 115 feet to 
the mile. The principal objection to the hypothesis of a connection between Relief Hill and the 
Derbec Shaft is that it requires the stream to follow a more northerly course than the old streams 
usually followed, —an objection less serious, it seems to me, than those which can be urged against 
other hypotheses. 
The highest banks exposed at present, those in the Eagle claim, are from 100 to 150 feet in 
height. From twenty to forty feet of the top of these banks are made up of red dirt and volcanic 
boulders, the excavations not yet extending back to the lava in place. Below this there comes a 
stratum of white gravel, composed of fine quartz with small streaks of sand and clay, not cemented, 
which, certainly on the northeastern rim, reaches quite down to the bed-rock. In some places the 
white gravel must be as much as 140 feet thick. Below the white gravel there is said to be a blue 
gravel on the deepest bed-rock, reached only by means of the shaft. 
The gold found at Relief Hill is mostly fine. In the Union claim nuggets worth from five to ten 
dollars are said to have been found, though rarely. 
In regard to the drift mine at Mount Zion there is not much to be said. Work has been carried 
on here at intervals for more than twenty years, but no one seems to have had the courage to 
thoroughly test the property, and to settle the question whether there is or is not a deep gold- 
bearing channel under the lava. The main tunnel runs nearly due west for a distance of 1,400 
feet, rising in that distance twenty-four feet. The tunnel is entirely in bed-rock, a hard meta- 
morphic slate. At the farther extremity of the tunnel there is an incline with a vertical rise of 
fifty-two feet, followed by a short, nearly level drift to the gravel. From the point where the 
gravel is struck there has been a drift run in a northerly direction for six hundred feet. This 
drift is supposed to follow the rim, for the bed-rock has a strong pitch to the west. The material 
of the gravel in this drift is almost exclusively quartz, with occasional bits of slate, well washed 
and rounded. The gravel is not very coarse, pebbles of three or four inches in diameter being 
among the largest. The gravel is not cemented. 
To the south of the main tunnel prospecting has been carried into what may be regarded as a 
branch or overflow. It was at this point that breasting was going on when I was there. The pay- 
streak is about three or three and a half feet thick, and on the bed-rock the gravel is frequently 
