448 STEVENSON— THE FORMATION OF COAL BEDS. [Nov. i, 



broken coal, but others are pebbles with the angles rounded. Their 

 coal differs from that of the beds in that it is less compact, absorbs 

 water, has less brilliant fracture and can be cut more readily. It 

 has the alternate bright and dull laminae of ordinary coal. Ap- 

 parently, the conversion was not complete when the fragments 

 were torn away and the interrupted process was not renewed. He 

 concludes that, during formation of the Commentry coal terrain, 

 there were frequent erosions of the earlier beds of coal, clay and 

 limestone ; that those beds do not 'belong, as might be imagined, to a 

 much older coal period ; that the coal, found as pebbles, is, so to 

 speak, less advanced, offering some properties differing from those 

 of plant materials fully converted in place; that the time required 

 for conversion of vegetable matter into coal, though very long, ap- 

 pears not to be excessive, since a coal basin of moderate size already 

 possessed some coal, while the deposits were increasing. There 

 can be no doubt respecting Renault's conclusion as to the source. 

 No rocks older than Middle Coal Measures are known to exist in 

 this basin of barely 12 square miles, which is divided by the broad 

 dejection cone of Montassiege, which contains no coal. 



Fayol's^® observations, recorded in his original work as well as 

 in the resume published in 1890, are of no slight importance in this 

 connection. Pebbles of coal, angular or rounded, in all shapes and 

 varying in size from mere grains to 4 decimeters, occur in all parts 

 of the terrain within the Commentry basin. They are rare in the 

 conglomerates but abound in the medium-grained sandstones of 

 both les Pegauds and les Ferrieres, the coal-yielding divisions sepa- 

 rated by the barren Montassiege area. They are associated fre- 

 quently with grains and pebbles of carbonaceous shale. The char- 

 acter of coal in the pebbles varies. Those in the older part of 

 the formation are anthracite, like the adjacent coals; those in les 

 Ferrieres are meager, as is the coal of that area; while those of les 

 Pegauds are of flaming coal like that from the Grande Couche. So 

 that the coals of the pebbles are like those of the immediate area. 

 At the same time, it is all-important to note that, according to Fayol, 



** H. Fayol, " fitudes sur le terrain houiller de Commentry," livre premier, 

 Bull. Soc. Ind. Min., 2me Ser., Vol. XV., 1887, pp. 140, 141. 



