76 FAIRBANKS AND RAMPART QUADRANGLES. 
valley walls the exposure of igneous rocks seems to be greater than in 
their upper parts; that is, erosion seems to have exposed larger masses 
of igneous rocks. Small veins of quartz and calcite occur in the rocks, 
but none of great extent. The rocks of the valley have a considerable 
impregnation of iron pyrites, the oxidation of which has stained them 
the familiar rusty brown of iron oxide. 
The placer deposits are all in the stream bed. The valley has been 
cut down so quickly that no bench deposits have formed. The alluvial 
deposits of Little Minook Creek vary in thickness from 7 to 25 feet, 
of which gravel forms 3 to 12 feet, and muck, though occasionally 
absent, generally 3 to 1G feet. The deposits are shallowest in the 
lower part of the creek. The gravels contain fragments of many 
rocks, of which diabase is probably most abundant, but slate, grit, and 
much vein quartz also occur, and there are many large quartzite 
bowlders from the bench above. Much of the gravel, as would be 
expected in a weak stream, is subangular. 
In the gravels mammalian bones are said to be found, although 
none were seen b}^ the writer. In places clear ice is uncovered in 
digging, the structure of the alluvium showing how sudden floods had 
drifted detritus over the ice in the spring, and had thus preserved it. 
Locally there is much wood in the muck. 
Occurrence and character of the gold. — Values are found in the 
lower part of the gravels through a thickness of 1 to 3 feet, and a 
width of 50 to 200 feet. The gold frequently occurs in the bed rock, 
particularly the broken diabase, to a depth of 1 to 2 feet. The pay 
streaks extend up the creek only as far as the creek has cut through 
the high bench gravels, a distance of about 3 miles. There are sixteen 
1,000-foot claims within these limits. 
The creek has been well prospected throughout its length, and 
although colors are found there is no pay above the line of the high 
bench. A small amount of gold, in which were some large nuggets, 
has been found in the gulches leading from the high bench. The 
amount of gold carried by the gravels varies greatly, but in the pay 
streak probably runs from $2 to $10 per square yard. The gold is 
generally smooth, chunky, and bright (PI. Ill, j, k), and shows a 
large amount of wear. In the upper part many nuggets are found 
weighing 1 to 12 ounces apiece, but the gold gets finer downstream 
until near the mouth it is nearly all flat, smooth, bright, and even in 
size, looking like golden bran when seen in quantity. There is a very 
small amount of rough gold, probably of local origin, but the larger 
part is probably reconcentrated from the old bench gravels of Minook 
Creek. The gold of the creeks cutting this bench is said to assay over 
$19 per ounce. This would make it of about the same value per 
ounce as the Koyukuk gold. The gold is taken in trade by the stores 
