collier.] GLENN CREEK GOLD MINING DISTRICT, ALASKA. 51 
tainty, but the evidence indicates that the Rampart series is younger. 
If this be true, the schist series of the upper part of Minook Creek 
and of Glenn Creek may be correlated with either the Fortymile or 
the Birch Creek series of Spurr. No evidence of faulting or intru- 
sions of granite in this series, as indicated by Spurr, a was seen along 
Minook Creek by the writer. The rocks contain small quartz veins 
and stringers in many places, and the debris from them includes peb- 
bles of igneous material other than granite, suggesting the presence 
of intrusions of various kinds. 
A few specimens of the sedimentary rocks have been examined micro- 
scopically. These vary in degree of alteration, in some cases being 
garnetiferous mica-schists, in others quartzites consisting of inter- 
locking quartz grains. All the specimens examined contained more 
or less muscovite. Microscopically these rocks resemble the Birch 
Creek series as described by Spurr. 6 A similar series of schists 
occurring at many places along the Tanana River c has been described 
by Brooks under the name Tanana schists. They outcrop for some 
distance along the Tanana below the mouth of Baker Creek, making 
it probable that the schist series forms a continuous area from Minook 
Creek, 8 miles above Rampart, to the Tanana below Baker Creek. 
These schists have been correlated by Brooks d with the Birch Creek- 
Fortymile series of Spurr. 
DESCRIPTION OF PLACERS. 
Glenn Creek is a small stream, in summer carrying less than a 
sluice-head of water, which rises in a bench on the north side of 
Baker Flats and flows southward to the flats. The creek occupies a 
broad, shallow depression less than 50 feet deep, which makes a hardly 
noticeable break in the topography. 
About one-half mile west of Glenn Creek, Gold Run, a still smaller 
stream, also flows southward to Baker Flats, and about one-half mile 
farther west Rhode Island Creek, a larger stream, has cut a deep 
trench nearly to the local base-level of Baker Flats. About a mile 
east of Glenn Creek, Eureka, a large creek, enters Baker Flats, also 
from the north, occupying a deep, well-marked trench. Each of the 
creeks named above carries placer gold in paying quantities for a dis- 
tance of about a mile, and the bench between Glenn Creek and Gold 
Run also has been found in places to be covered with gold-bearing 
gravel rich enough for exploitation. 
The productive placers of Glenn Creek are confined to four or five 
claims within a mile of the head of the creek. In this distance the 
creek bed has a fall of about 5 feet in 100. 
"Geology of the Yukon gold district: Eighteenth Ann. Rept. U. S. Geol. Survey, Pt III, 
PI. XXXVIII. 
^ Ibid., p. 144. 
cSee Reconnaissance in the Tanana and White River basins, Alaska, 1898: Twentieth Ann. 
Rept. U S. Geol. Survey, Pt. VII, map 24. 
"Ibid., pp. 468 and 469. 
