28 COAL RESOURCES OE THE rUKON". [no. 218. 
Eagle would .afford a market for a limited amount of coal, and it is 
not probable that workable beds would be neglected if they had beenj 
found. 
Seventymile Rimer. — This river enters the Yukon 25 miles below 
Eagle and 37 miles below the international boundary. It has a length 
of about 75 miles and flows nearly due east to its junction with the; 
Yukon. Coal is reported to have been found on this river and its 
tributaries several miles from the Yukon, but the writer was unable 
to obtain definite information regarding the occurrence. A great 
thickness of Kenai sandstone, not known to be coal bearing, is exposed 
at the mouth of Seventymile River. These coals of Seventymile 
River, if there be any, are undeveloped and are not known to be of 
economic importance. 
Washington Creek. — This stream, which is about 40 miles long ? 
enters the Yukon about 80 miles below the international boundary. 
Its headwaters oppose those of Seventymile River. 
The accompanying sketch map (fig. 1) shows the geologic relations 
of the three formations exposed along the creek. Near the Yukon is 
a broad belt of black slates of Lower Cretaceous age. These rocks 
overlie (see fig. 1) an intricate succession of limestones and tuffs 
belonging to the Rampart series, which occupy a belt about 2 miles 
wide, through which the creek has cut a narrow gorge. Both series 
are closely folded, the axes of the folds running about east and west. 
To the south is an area of coal-bearing sandstones, conglomerates, and, 
shales, whose southern limits were not determined. These beds are 
thrown up into broad, open folds, with dips of less than 45°, and 
overlie the older rocks unconformably. No fossils" were found in 
this arenaceous series, but on lithologic and structural grounds it 
is correlated Avith the Kenai. This view is substantiated by both 
the character and the mode of occurrence of the coal. These coal- 
bearing rocks first outcrop about 9 miles from the Yukon, in a great 
bluff of slightly consolidated conglomerate, rising about 100 feet 
from the creek bed. The strike here is to the northeast, and the dip 
at a low angle to the southeast. This is believed to be the base of the 
coal formation, since, if the dips are continuous, it underlies the area 
of coal- bearing rocks. Above this point the valley of Washington 
Creek broadens out into a wide, flat basin, with little relief, within 
which the creek meanders through long, quiet pools, with small rip- 
ples between. Few exposures of bed rock occur, although there is a 
great quantity of float coal on the gravel bars for a distance of 5 or 6 
miles above, which is as far as the writer traversed the creek. The 
prospect holes have caved in, so that for details of the coal sections 
the writer has been obliged to depend on the measurements made by 
prospectors. Their reports show a series of coal seams interbedded 
with soft sandstone and shale in several places, resembling, in a general 
