28 GOLD PLACERS OF RAMPART REGION. 
not over a half mile or a mile wide, and is probably at no place over 4 miles wide. 
On the east it is 5 to 7 miles wide through the greater part of the length of the creek. 
The total production of the Minook Creek group has been about $702,600, of which 
$75,500 was produced during the winter of 1903-4 and $10,900 during the summer of 
1904, making a total for the year of $86,400. 
The surficial deposits are derived from the country rocks, mostly slate, quartzite, 
and greenstone, and reach occasionally a depth of over 100 feet, though usually much 
less than that, and there is generally a large proportion of muck. 
MINOOK CREEK. 
General description. — Minook Creek empties into the Yukon just east of Rampart, 
and is about 25 miles long. Near its mouth it is a shallow stream 50 or 60 feet wide, 
with a flow of possibly 200 second-feet or 8,000 miner's inches. It flows in a north- 
erly direction through a deep valley whose width varies from a few hundred feet to 
about a half mile. The creek receives a number of large tributaries from the east — 
Hunter, Little Minook, Little Minook Junior, Hoosier, Florida, Chapman — and a num- 
ber of creeks whose names are unknown. From the west it receives Montana, Ruby, 
Slate, and Granite creeks and a few small tributaries. Granite Creek, about 17 miles 
from the Yukon, is the largest western tributary, carrying probably 30 to 40 second- 
feet; Minook Creek carries perhaps 40 to 50 second-feet at the junction. These 
approximate estimates are given to convey some idea of the comparative sizes of the 
streams. 
Aneroid barometer readings by Mr. Arthur J. Collier « showed a descent of about 
760 feet from the "106 road house," about H miles above Granite Creek, to the 
Yukon. As the distance is about 18 miles, these readings indicate a gradient of about 
42 feet to the mile. In the next 3J miles above he noted a rise of 240 feet, showing 
a gradient of about 68 feet to the mile. According to Mr. M. E. Koonce, b of Ram- 
part, the creek has a fall of about 40 feet in the vicinity of the mouths of Ruby and 
Slate creeks. Aneroid barometer readings of Mr. L. M. Prindle and the writer 
showed a somewhat higher grade for the central portion of the creek. It seems 
likely that Minook Creek has an average gradient of somewhat over 40 feet per mile 
from the Yukon to Slate Creek and a somewhat steeper gradient above Slate Creek. 
Just below the mouth of Slate Creek the Minook spreads into a number of branches 
in a wide gravel flat. This flat, which is typical of many Alaskan streams, is prob- 
ably due to a change in the grade of the creek. The stream here is unable to carry 
the gravels of the swifter water above, and so spreads them upon the flat. .Here are 
found the so-called "winter glaciers," which sometimes last through the short sum- 
mers. In 1904 a quarter or half acre of ice still remained when the September frosts 
occurred. This ice owes its origin to the fact that the channel which carries the 
water is greatly contracted by freezing in the fall. The resulting hydrostatic pressure' 
cracks the ice and the water overflows and freezes. This process is repeated until a 
considerable thickness of ice is accumulated. 
The valley is V-shaped in cross section, and the eastern slope is often benched, 
w r hile the western is more abrupt and has remnants of benches at but few places. 
Five well-marked benches rise at irregular intervals above the floor between Little 
Minook Junior Creek and Hoosier Creek (fig. 1), the highest of which is about 500 
feet. These benches are features of much importance in both the physiography and 
economic geology of the region. Important gravels cover the highest one, which 
lies on the east side of the Minook and extends from Hunter Creek to about a mile 
above Florida Creek. It will be described later. A small remnant ol the same 
bench is found on the north side of the mouth of Montana Creek and another on 
a Personal communication. In giving aneroid barometer readings their lack of reliability is recog- 
nized in all cases. 
b Personal communication. 
