STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 127 



like bituminous coal while those from others are lignitic. There is 

 a marked variability in the percentage of ash. In burning, this 

 coal gives off an enormous volume of smoke. 



Pardee^'^^ has recorded brief notes respecting deposits in Mon- 

 tana, which appear to be on the border line between Miocene and 

 Oligocene. They are lenticular and consist of remains of vegeta- 

 tion, which grew on the fiats, mingled with silts from the muddy 

 water which frequently flooded the spaces. The coal attains a maxi- 

 mum thickness of 7 feet, is banded, with alternating bright and 

 dull laminae, has semi-conchoidal fracture, splits along the bedding 

 planes and has two sets of joints, intersecting at right angles. It 

 is usually dense and brittle, but at one mine some of the layers are 

 rather tough and woody. The streak is brownish and the coal tends 

 to slake on exposure. The dip throughout the region is gentle. 



The Miocene coal of Greenland was discovered long ago and it 

 has been utilized in a small way. Brown^"* gave numerous sections 

 from one area. The important bed of the region explored by him is 

 on Heer's creek, wdiere it is double, showing coal, 2 feet 6 inches, 

 shale, I foot 6 inches, coal, i foot. The coal is but slightly coherent, 

 has cubical fracture and breaks down readily on exposure. Retinite 

 is abundant in lumps from mere specks to the size of a marble. 

 Many stems of trees are in the upper bench, but they have been 

 replaced with chert. Somewhat later, Heer^'^ described a bed of 

 coal near Discovery Harbor, 25 to 30 feet thick and with extreme 

 dip of 10 degrees. The overlying black shale is rich in plant 

 remains ; among which, as in Spitzbergen, conifers hold the first 

 place, ten species having been recognized ; with them are eight species 

 of dicotyledons, belonging to families usually well represented in 

 swamp floras, such as birch, elm, waterlilly and other types of similar 

 habit. Heer regards the whole assemblage as indicative of swamp 

 origin for the deposit. The coal falls to pieces readily on exposure; 



^■^3 J. T. Pardee, " Coal in Tertiary Lake Basins of Southwestern Mon- 

 tana," U. S. Geol. Survey, Bull. 531 G, pp. 11-15. 



1"* R. Brown, " Geological Notes on the Noorsack Peninsula," etc.. Trans. 

 Geol. Soc. Glasgow, Vol. V., 1877, pp. 91, 95. 



i"2 O. Heer, " Notes on Fossil Plants Discovered in Grinnell Land," 

 Quart. Journ. Geol. Soc, Vol. 34, 1878, pp. 68-72. 



