450 SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION. 
that gold in more than the average quantity is found along the surface of junction between the 
boulders and the fine gravel. This statement I had no means of verifying. The boulders which 
make up the great body of the boulder stratum are largely though not exclusively of volcanic 
origin. At the lower end of the hill, where the side gravel has not been removed to so great an ~ 
extent as elsewhere, [ had a good opportunity to see these boulders in place. A large number of 
them differed decidedly from the common type of tufaceous rock, which prevails at higher altitudes 
on the ridge. They presented rather the appearance of metamorphic crystalline rock, such as might 
be expected to compose the bed-rock somewhere in the mountains. 
The principal pay-streak at Indian Hill is near the bed-rock. The gold is fine, the coarsest 
pieces seldom being worth more than two or three dollars. There is an abundance of large blue 
boulders in the pay-streak. At the upper end of the hill I noticed, resting upon the bed-rock, a 
stratum of about four feet in thickness of a black clay, containing abundant impressions of leaves 
and wood, but it was too fragile to furnish good specimens that would bear transportation. 
The water used at Indian Hill is drawn from the heads of Indian Creek and from one of the 
branches of Humbug Creek, also a tributary of the North Yuba. 
A little more than a mile to the east of Indian Hill, upon the spur which lies between Humbug 
Creek and the North Yuba, there is a mining claim known as Snowdon. I did not visit the local- 
ity, but was told that there is a boulder stratum there, like that at Indian Hill, which rests directly 
upon the bed-rock, without any fine gravel. It is suggested that the clean quartz gravel of the 
* lower stratum of Indian Hill may belong to the old channel which flowed between Brandy City 
and Camptonville, and that the boulder stratum and voleanic capping belong to a later stream, 
which came from a different direction, and which may possibly be recognized again at Pittsburgh 
Hill, one of the outlying deposits to which I will next call attention. 
The exact position of Pittsburgh Hill I am not able to give. It lies upon a long spur between 
Lost Creek and the North Yuba, about a mile below the mouth of Slate Creek, and seven or eight 
miles in a northwesterly direction from Camptonville. It is near the point where the course of 
the North Yuba changes from westerly to southerly. The course of Lost Creek from Pittsburgh 
Hill is first southerly and then westerly to the Yuba. There are four mining claims at this place. 
The most westerly is known as the Pittsburgh Hill claim; and this is followed by the Oshawa, 
the California, and still farther east by another, the name of which I do not know. There have 
been in the past some attempts to employ the hydraulic process, but at present, attention is directed 
solely to tunnelling and drifting. The mouth of the Oshawa tunnel is about a thousand feet in a 
direction a little north of west from the mouth of the California tunnel. The true course of the 
Oshawa tunnel is N. 49° E.; and that of the California tunnel is N. 2° W. for the first 468 feet, 
after, which for nearly 500 feet farther, the course is N. 224° W. The altitude of the mouth of 
the California tunnel I made to be 2,860 feet; the Oshawa tunnel is eleven feet higher. The 
difference of level between Pittsburgh Hill and the boulder stratum at Indian Hill will allow a 
grade of nearly eighty feet to the mile between the two places. There is no direct evidence, how- 
ever, of the existence of any channel between them: if such a channel did exist, the present North 
Yuba has cut it entirely away. To the east of Pittsburgh Hill bed-rock rises to a height of six or 
seven hundred feet above the level of the gravel, and thus shuts out the possibility of any channel 
coming in from that direction. I did not examine the Yuba slope of the hill, but I was told after 
my return to Camptonville that a channel of 150 feet in width can be seen entering the hill from 
that side. 
The bed-rock at Pittsburgh Hill is a soft, easily worked granite. The gravel contains consider- 
able rotten granite, and in the pay-streak, which is confined within two and a half feet of the bed- 
rock, the boulders are heavy. The body of the gravel, which is 137 feet in thickness, and barren 
of gold, is composed of washed and rounded voleanie pebbles mixed with granite. Some of the 
lava boulders are decomposed and soft, others are still hard. 
The gold is black and rusty. I was allowed to take a few small pieces from the Oshawa dirt. 
They have been examined by Mr. Wadsworth. He says the gold is “covered partly by a dark 
