PLACERS OF THE RAMPART REGION. 67 
The surfieial 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 gener- 
ally 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 northerly 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 number of creeks whose names are un- 
known. 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 con- 
vey some idea of the comparative sizes of the streams. 
Aneroid barometer readings by Arthur J. Collier a showed a de- 
scent of about 760 feet from the " 106 road house," about 1^ 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 3^ miles above he noted a rise of 240 feet, showing a 
gradient of about 68 feet to the mile. According to M. E. Koonce, 6 
of Rampart, the creek has a fall of about 40 feet in the vicinity of 
the mouths of Ruby and Slate creeks. Aneroid barometer readings 
of 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 probably 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 summers. In 1904 a quarter or half acre of ice still re- 
mained Avhen the September frosts occurred. This ice owes its origin 
to the fact that the channel which carries the water is greatly con- 
" Personal communication. In giving aneroid barometer readings their lack of reliability 
is recognized in all cases. 
b Personal communication. 
