I9I3.] STEVENSON— FORMATION OF COAL BEDS. 95 



inclined to believe that it was formed in free air, exposed to heat and 

 moisture. FayoP°" found fusain very abundant in the Grand Couche 

 of Commentry. It occurs in isolated or grouped fragments between 

 bright and dull laminae, sometimes in heaps several meters long and 

 10 to 20 centimeters thick; he found it in the axes of brilliant 

 laminae of branches, especially of Cordaites, and in very numerous 

 small fragments in the cannel. Fayol presents many facts which 

 lead him to believe that fusain was formed by decomposition of 

 plants in the air. 



This material has been regarded by many writers as anthracitic. 

 Perhaps it may have been so before burial, but the supposition that 

 it could not be impregnated with substances coming from decomposi- 

 tion of the surrounding vegetable material seems to be disproved by 

 jMcCreath's^"^ analyses. At the same time it contains usually less 

 volatile matter than is found in the enclosing coal, showing appar- 

 ently that its origin was different. The analyses show a volatile 

 content of from 6.40 to 30.74 per cent. The highest proportion is 

 in specimens from a coal bed underlying the Homewood sandstone, 

 in which the volatile is 48.140; a specimen with 11.36 is from a coal 

 with 26.500; but there is one result, the average of several analyses, 

 which gives 20.98, while the surrounding coal has only 17.070; the 

 lowest, 6.40, is from a coal containing 21.410; while in one anthracite 

 coal, the fusain contained 8.60 while the coal itself had 8.830. It is 

 sufficiently evident that the volatile of the mineral charcoal bears 

 relation in quantity to that of the enclosing coal. 



The suggestion that mineral charcoal was derived from forest 

 fires cannot be accepted as a possibility. The quantity produced by 

 a forest fire is comparatively insignificant. The writer is sufficiently 

 familiar with the subject to form a judgment. The Indians were 

 accustomed to set fire to forests in many portions of the Rocky 

 INIountains in order to drive the game to lower levels. The fires 

 destroyed the bark and leaves but left the trunks little more than 

 scarred. These remained upright until, weakened by decay, they 

 were overturned by the wind to form the " laced timber," which was 



"" H. Fayol, " fitudes," etc., pp. 149, I77- 



"" A. S. McCreath, Sec. Geol. Surv. Pcnn., Rep. MM, 1879, pp. 106, 107. 



