472 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



of coal; lo which may be utiHzed when the thicker ones have been 

 exhausted, and 8 which are too thin ever to be mined. The highest 

 seam is the Ste.-Barbe, with maximum of a meter and a half, which 

 is double — a characteristic of the thicker seams. Veine 9, long 

 mined at one colliery, is of uncertain value, for within a few meters 

 it may change in thickness from 3 or 4 meters to a petty veinette. 

 It is always in a single bench and has a f aux-toit. The coal is very 

 clean and much prized for manufacture of illuminating- gas, though 

 it has little lump. The thickest seam is the Veine a trois sillons, 

 with 0.60, 0.40, 0.40 of coal and 0.30 of bituminous shale in two 

 partings ; it yields 60 per cent, of lump coal. 



The faisceau de charbons gras, 190 meters thick, has 5 workable 

 seams with 3.50 meters of coal. The seams are irregular and some 

 of them are merely local ; one, a meter thick at the west and yielding 

 excellent lump coal, becomes poor toward the east and at length is 

 replaced with sandstone. In its roof are vertical Catamites, of 

 which the roots are in the coal. The demi-gras faisceau has five 

 thin but workable seams, one of which has Stigmaria in the roof. 



Coals from the highest faisceau have 28 to 32 per cent, of vola- 

 tile, those of the middle have 25 to 28, and those of the lowest have 

 22 to 25. Breton asserts seams cannot be identified or their position 

 determined by means of composition. 



Rock Fragments in Coal. — The presence of rock fragments in 

 coal seams has been observed by Stainier and Schmitz in Belgium 

 and by Barrios in France. 



Stainier'^ found rolled pebbles in the 500-meter level of a seam 

 near Charleroi, where they are not uncommon; but none has been 

 found in the 2So-meter level. They are rounded and have a coaly 

 covering. The dimensions of two of them are 0.07 by 0.045 by o.io 

 and 0.14 by 0.08 by 0.16 meter. These are quartzitic sandstone. A 

 similar pebble from a seam in the Huy district is 0.15 by o.io by 

 .0.04, rudely triangular and the edges are rounded. Schmitz obtained 

 ■'from the Veine Leopold near Charleroi sandstone pebbles, perfectly 

 Tounded and covered with a crust of coal. Stainier saw large, 

 rounded pebbles in the Grande Veine at Gosselius. They are pres- 



■^1 X. Stainier, " On the Pebbles found in Belgian Coal Seams," Trans. 

 Manch. GeoJ. Soc, Vol. XXXIV., 1896, Sep., pp. 1-19. 



