50 COAL RESOUECES OF THE YUKON. [no. 218. 
river, and from the cliff the hill slopes back more gently to an eleva- 
tion of about 600 feet above the river, as shewn by Gerdine's map of 
the mouth of the Koyukuk. a 
At the Pickart mine one coal seam has been exploited, which strikes 
N. 75° E. and dips N. 35°. Two rolls, or horsebacks, are reported to 
occur in the floor of the coal bed. Whether these are in the nature 
of faults, due to movement of strata along the coal bed, or irregulari- 
ties in deposition of the sediments constituting the floor, the writer 
was unable to determine. Near these rolls the coal shows considera- 
ble crushing, which suggests that the roll is caused by deformation. 
The Pickart coal bed has a thickness of 30 inches at a distance of 300 
feet from the entrance to the mine, but at the end of the main gang] 
w ay, 600 feet from the entrance, near one of the rolls above referred 
to, the seam measured only 18 inches. Mr. W. E. Williams, mana- 
ger of the Pickart mine, reports that in mining this coal a roll was 
encountered in the workings above the main gangway, in which the 
floor of the bed was raised up, pinching the coal down to a knife-edge 
thickness. This roll extended in a nearly straight line and approached 
the gangway at the rate of about 1 foot in 20. On cutting through 
this roll good coal was found, having a thickness of 3 feet, which con- 
tinued for about 2<> feet, when another roll parallel to the first was 
encountered. The second roll has not been passed through in the 
workings of the mine. The coal near these rolls is crushed and impure 
and the bed pinches down to a knife-edge thickness. It is probable 
that coal will be found beyond the second roll in the floor, so that the 
commercial extent of the seam in this territory has not been deter- 
mined, nor has it been traced below the river level. 
The Pickart coal makes a good coke and must be classed as dis- 
tinctly bituminous. Samples were taken from the main gangway 
300 feet from the surface and from the end of the gangway 600 feet 
from the surface, and these were analyzed by Allen, of the United 
States Geological Survey. The second sample is interesting as show- 
ing the character of the coal in the vicinity of the rolls in the floor, 
which led to the abandonment of the mine. 
Andhjxix of coal (No. 252) from Pickart mine, 200 feet from entrance. 
Per cent. 
Water 1. 02 
Volatile combustible matter 
Fixed carbon 
Ash 
Sulphur . . 
Fuel ratio. 
27. 33 
65. 03 
6.62 
100. 00 
0.60 
2.38 
Coke compact. 
a Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 2, 1900, pi. lx. 
