ECONOMIC GEOLOGY. 
39 
part of the valley is from one-half to three-fourths of a mile in width 
and from this floor the walls rise with gentle slopes. Gold has been 
found on Pedro and Gilmore, Engineer, Big Eldorado, and O'Connor 
creeks and on Eox Gulch, all tributary to Goldstream Creek. The 
bed rock throughout most of the basin is probably mica schist, but 
granite has been found on several of the tributaries, notably on Pedro 
and Gilmore creeks. Pedro Creek was the scene of the first discovery 
of gold (1902) and this creek and the main stream have been large 
producers in the last two years. The alluvium of the basin ranges 
in depth from a few feet in the headwater region to more than 200 
feet near the lower limit of discovery on Goldstream Creek. The 
gravels consist predominantly of mica schist, with considerable quartz 
and some granite. 
Most of the work on Goldstream Creek during 1907 was confined 
to the portion of the valley from Discovery claim, near the confluence 
of Pedro and Gilmore creeks, to about IT below Discovery. The pay 
streak from Discovery to about 7 below lies on the north side of the 
creek ; below this point it is on the south side. The limit of profitable 
mining, as determined by present methods and costs, is probably $1.50 
to $2 a cubic yard. If a cheaper method of handling the gravels 
could be devised it would make available for mining an enormous 
body of gravel. The following table shows the thickness of the de- 
posits in the upper part of the valley so far as known. . 
Depth of bed rod-, thickness of muck, and width, of valley floor along Gold*- 
stream Creek. 
Claim No. 
Depth to 
bed rock. 
Thickness 
of muck. 
Width of 
valley 
floor. 
Discovery to S below -_ . __ ._ __ 
Feet. 
15-20 
22 
25 
20 
45-60 
70 
110 
80 
65 
60 
Feet. 
Feet. 
1,000 
8 below.. 
9 
12 
9 below . ... 
10 below 
1,500 
12 below 
30 
2,500 
3,000 
15 below_ 
3,000 
3,000 
17 below 
3,000 
27 below _ . 
3,500 
29 below . 
90] 
i::u 
150J 
32 below . . 

160 
158 
2,500 
37 below ..__. _ _ ._ _ 
The Pedro Valley is similar in general character to the Fairbanks 
Valley, already described. The productive area includes about 2 
miles of the stream between the mouth of Twin Creek and the point 
where it is joined by Gilmore Creek. The deposits have a thickness 
ranging from about 8 to 30 feet. Values have been found in some 
places through 8 feet of gravel and 4 feet of bed rock; in other places 
they are confined mostly to the bed rock. 
Gilmore Creek, which joins Pedro to form Goldstream, Hows in a 
general northwesterly course and has a length of about 5 miles. The 
