collier.] NAHOCLATILTEN COAL BED. 47 
eastern boundary of this field, while south of the Yukon low flats 
extend for several miles to the foothills, which are composed of rocks 
believed to be older. Northward the field extends up Koyukuk River 
for a distance of at least 35 miles, and it extends westward probably 
to Norton Sound. At its northern and western boundaries it is over- 
lain by younger effusives and sediments. 
The coal occurs in beds which are not known to have great exten- 
sion. These will be described under the headings Nahoclatilten coal 
bed, Pickart coal mine, Nulato coal bed, Bush mine, Blatchford mine, 
Williams (Clemens Thein) mine, Coal mine No. 1, and Halls Rapids 
coal. Reported coal prospects not visited by the writer will be men- 
tioned under the headings upper Koyukuk and Anvik River. 
Nalhoclatilten coal bed. — Bluffs of sandstone extend up the west 
bank of the Yukon from Nahoclatilten" for about 20 miles, nearly to 
the mouth of Melozi River, and are coal bearing about 5 miles above 
the village. These coal seams were examined at only one locality 
by the writer. Coal has probably also been found at a number of 
places in this vicinity, which is roughly located about 50 miles above 
Nulato and on the right bank of the Yukon. 
The geologic relations of these coals are of exceeding interest, 
though at the present time only imperfectly known. The coal seams 
were found about one-fourth of a mile from the river in sandstones 
and shales carrying Kenai fossils, and hence of Eocene age. This 
sandstone stands nearly vertical, and from it an ancient slide extends 
to the river. From the foot of this slide on the river bank fossil 
plants referable to the Middle or Lower Cretaceous were collected, as 
well as fossils referable to the Kenai. About one-fourth of a mile up 
the river from this point there is a high bluff composed in part of cal- 
careous sandstone and in part of intrusive basalt. From the sandstone 
abundant marine fossils referable to the Upper Cretaceous have been 
collected. 
Two beds of coal were seen by the writer at this place, and two 
more are reported to have been uncovered in prospecting. The 
largest observed seam has a thickness of 1 foot. Below this seam 
there are about 5 feet of bony coal or coaly shale with stringers of 
coal. There are reported to be three smaller beds in the foot wall, 
each having a thickness of 10 inches. Owing to the apparent rather 
intense folding of these beds it is impossible to place much reliance 
on these statements. 
The coal in the 1-foot seam is not crushed, although the beds are 
much disturbed in position. The following analysis shows it to be a 
bituminous coal of good quality. It is reported to have given satis- 
factory results in a blacksmith's forge. 
cThe United States military telegraph post here located was officially known by this name in 1902, 
but in 1903 the name was changed to Louden. 
