ECONOMIC GEOLOGY. 43 
Though staked some years before, the first systematic prospecting 
was done in 1906 and met with only moderate success. The gravels 
were found to be auriferous, but no pay streak had been discovered 
at the time of the writer's visit. It is reported that in 1907 values 
were found on one claim and some gold taken out. 
The valley of Eldorado Creek, lying as it does between two of the 
important gold producers, certainly deserves careful prospecting. 
There appears to be good reason to believe that it will yet become a 
producer. 
DOME CREEK. a 
Dome Creek, also a tributary of the Chatanika, heads in the west 
side of Pedro Dome. The bed rock and gravels are similar to those 
of Cleary Creek. The depth to bed rock where the ground is being 
worked ranges from 30 to 200 feet. The .slope of the bed rock in 
the lower part of the valley is about 15 feet to the mile. The surface 
of the bed rock is uneven, variations of 15 to 20 feet being common. 
The pay streak has been found to be from 130 to 165 feet Avide. The 
material includes 2 to 3 feet of bed rock and 2 to 3 feet of gravel. 
Good reports were coming from nearly the entire length of the creek 
in September, 1907. 
VAULT CREEK. 6 
Vault Creek, about 6 miles in length, flows northward into the 
Chatanika, and is adjacent on the west to Dome Creek. Bed rock is 
probably schist throughout the basin, but there are no exposures ex- 
cept on the round ridges. 
The east wall of the valley rises by a gentle slope; the west wall is 
more abrupt. This gentle slope appears to be underlain by a heavy 
deposit of muck having a maximum thickness between 50 and 75 feet 
and thinning out toward the creek as well as toward the ridge. lie- 
low this muck there is a deposit of sand and fine gravel with some 
clay — 30 to 60 feet thick — overlying coarse gravel which is aurifer- 
ous. The depth to bed rock varies greatly, being determined by -lie 
position of the shaft, whether on the creek bed, where the alluvium 
is said to be not more than 50 feet deep, or on the talus slope, where 
it may be 200 feet, 
The pay streak is reported to be 100 feet or more wide, with ;i 
thickness of 3 to 6 feet. It has been rather definitely traced for a 
couple of miles along Vault Creek below the mouth of Treasure 
Creek, and for half a mile up the latter stream. Little prospecting 
has been done on the lower part of Vault Creek, where the alluvium 
is said to be very deep. Near its mouth, in the Chatanika flats, the 
" By Alfred II. Brooks and C. <'. Covert. 
6 The information on Vault Creek was obtained bj Alfred n Brooks In L907. 
