COAL RESOURCES OF THE YUKON BASIN, ALASKA." 
By Arthur J. Collier. 
INTRODUCTION. 
The coal beds of the Alaskan part of the Yukon Basin occur in soft 
sandstones and shales, with intercalated beds of conglomerate. These 
beds are in part in the Nulato series of the Upper Cretaceous and 
in part in the Kenai series of the Eocene. The two series are appar- 
ently conformable and have strikingly similar lithologic characters. 
They can be separated only after close stral [graphic and paleontologie 
study, and hence it is not now possible to state definitely what part 
of the coals are Cretaceous and what part are Eocene 
For the purpose of discussing its coal resources the Yukon Basin of 
Alaska may be divided into three provinces. The Upper Yukon 
includes that part of the valley lying between the international 
boundary and the great lowland known as the Yukon Flats. The 
Middle Yukon includes that part of the valley lying between the 
Yukon Flats and the mouth of the Tanana, and the Lower Yukon the 
portion of the valley from the mouth of the Tanana to the sea. In 
the Upper and Middle Yukon provinces the coal-bearing rocks occur 
in small basins surrounded by older rocks. The sandstones of these 
basins, as far as determined, belong to the Kenai series, and are cor- 
related with the coal-bearing beds of southern Alaska. With a single 
exception these coals are either high-grade lignites or lignitic bitumi- 
nous coals. h 
The coal-bearing beds of the Lower Yukon are exposed continu- 
ously for 200 miles along the river, and they probably extend west- 
ward to include the area which has been reported near Norton Sound. 
This terrane is made up of sandstones, shales, and conglomerates, 
which probably form an uninterrupted sedimentary series, ranging in 
age from the Middle Cretaceous to the Upper Eocene, and hence 
including both the Nulato and the Kenai series. Both these series 
carry coals of economic importance in this province, practically all of 
which are of a bituminous character. 
In the following pages the localities will be described according to 
"Abstract of paper in preparation. 
& A coal whose content of water is above 10 per cent and whose fuel ratio is less than 1 is 
regarded as a lignite. The fuel ratio is the quotient of the fixed carbon divided by the volatile 
combustible matter. Coals whose classification by this rule is in doubt have been called lignitic 
bituminous coals. 
276 
