STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 413 



from bark of coniferous trees and that the dull, splinty laminae, con- 

 taining a notable proportion of mineral charcoal, were derived from 

 Glossopteris stems and leaves. Sporangia abound but not in quan- 

 tity to give spore coal. 



The prevalence of V ertehraria makes probable that the peaty 

 swamps, now represented by the coal seams, began as fern brakes 

 with reeds. He had never seen a tree stump in the underclay. 

 The swamps at length became Waldmoors, covered with Dadoxylon 

 forests. These, at several horizons, were overwhelmed by showers 

 of volcanic dust and drops of resin were preserved in considerable 

 quantity within this dust. 



Cannel occurs as lenses within the thick Greta seam ; the oil 

 shale or Hartley mineral occurs in like manner as lenses within the 

 coal, These, at times, are of considerable lateral extent and occa- 

 sionally that mineral forms a more or less persistent bench, in which 

 the richness varies greatly. The character of coal is rarely the same 

 throughout a seam, cannel, splint and bright bituminous being found 

 frequently in the section of a single seam. 



India. 



The Permo-Carboniferous of India is exposed in isolated fields, 

 large or small, within a strip, crossing Hindostan between parallels 

 19 and 24. These deposits, belonging to the Lower Gondwana, are 

 divided into the Panchet, Raniganj, Barakar and Talchir, of which 

 Panchet has been referred to the Trias. The Raniganj and Barakar 

 are equivalent to the Upper and Lower Damuda and, in much of 

 the region, are separated by a mass of clayey to sandy and carbo- 

 naceous shale, holding much clay iron stone. Coal is confined prac- 

 tically to the Damuda beds, there being only occasional carbonaceous 

 shale and local seams in the Talchir. This lowest member consists 

 of greenish, at times sandy or gravelly muds, frequently containing 

 pebbles and large blocks of rock, so that, in places, there is a distinct 

 bowlder bed. The variations of the Permo-Carboniferous can be 

 made clear by examination of several fields from east to west. 



The Rajmahal fields is northeast from Calcutta between the 



