58 COAL RESOURCES OF THE YUKON. [no. 218. 
a conchoidal fracture. The analysis indicates a fuel of good quality, 
but the coal is not believed to have any economic value because of its 
limited extent. 
Anvik River. — Mr. J. W. Chapman, missionary at Anvik, reported 
to the writer the occurrence of coal on Anvik River about 50 miles 
above its mouth. This point is probably about 10 miles back from 
the Yukon, and in a general way west of the sandstone bluffs in which 
the Williams mine coals occur, and probably represents a western 
extension of the same held. No attempt has been made to open this 
coal, but it hnds a limited use among the natives in their manufacture 
of black paint. 
CLASSIFICATION OF YUKON COALS. 
The coals of the Yukon Basin occur in sandstones of Tertiary and 
Cretaceous age and present great variations in quality, due probably 
in part to primary differences in composition and in part to meta- 
morphic influences which have acted more or less locally. They range 
from high-grade lignites to semibituminous coals. 
In the classification of the Yukon coals some uncertainty and con- 
fusion arise from the distinction to be made between lignites and 
bituminous coals. The same confusion prevails in regard to the coals 
of western United States." 
The geologists who first studied the coal fields of the Rocky Moun- 
tain region, finding that the coals were contained in rocks younger 
than the Carboniferous, classed as lignites all of the post-Paleozoic 
coals. The same classification, based on stratigraphic position rather 
than character of the coal, has been carried to Alaska, and many coals 
shown by their analyses to be bituminous have been classed as lig- 
nites. h The table of analyses on page 61 shows that many of the 
Yukon coals compare favorably with coals classed as bituminous in 
eastern United States. 
The fuel value of coal is to a certain extent indicated by the fuel 
ratio/ This varies from less than 1 in lignites and some cannel coals 
to more than 20 in some anthracites. In lignites, as the fuel ratio 
decreases the percentage of water increases. In general, d it may be 
a Knight, Wilbur C, Coals and coal measures of Wyoming: Sixteenth Ann. Kept. U. S. Geol. Sur- 
vey, pt. 4, 1895, pp. 208-215. Hills, R. C, Coal fields of Colorado: Mineral Resources U. S. for 1892, 
U. S. Geol. Survey, 1893, pp. 319-365. Taff, J. A., Preliminary report on Camden coal field of south- 
western Arkansas: Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 2, 1900, pp. 313-329. Taff and 
Adams, Geology of eastern Choctaw coal field, Indian Territory: Twenty-first Ann. Rept. U. S. Geol. 
Survey, pt, 2, 1900, pp. 257-311. Storrs, L. S., The Rocky Mountain coal fields: Twenty-second Ann. 
Rept. U. S. Geol. Survey, pt. 3, 1902, pp. 422-471. Hayes, C W., Coal fields of the United States: 
Twenty-second Ann. Rept. U. S. Geol. Survey, pt. 3, 1902, p. 19. 
&Dall, W. H., Report on coal and lignite of Alaska: Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 1, 
1896, pp. 763-908. Brooks, Alfred H., Coal resources of Alaska: Twenty-second Ann. Rept. U. S. Geol. 
Survey, pt. 3, 1902, pp. 515-571. Summary Report Geol. Survey of Canada, 1901, pp. 46-48. 
c The fuel ratio is the quotient obtained by dividing the percentage of fixed carbon by the percent- 
age of volatile combustible matter. 
d Hayes, C. W., Coal fields of the United States: Twenty-second Ann. Rept. U. S. Geol. Survey, pt. 3, 
1902, p. 19. 
