STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 419 



Ir the central part of the district, MedHcott^' grouped the Permo- 

 Carboniferous into Talchir, Lower and Upper Damuda. The Tal- 

 chir has the famihar features and at most is about 600 feet thick. 



The Lower Damuda (Barakar and Ironstone shales) has an ex- 

 treme thickness of not far from 11 50 "feet. The rocks are mostly 

 sandstone and sandy shale, but there is a considerable proportion 

 of black shales. At times, the sandstones are rippled and often are 

 crossbedded. The deposition was irregular; sandstones pass to 

 shale abruptly. Glossopteris, V ertehraria and Phyllotheca are abun- 

 dant at several horizons. The coal seams, for the most part are 

 thin and, with one exception, are without value, while, at best, they 

 are mere lenses. The Upper Damuda (Raniganj), about 150 feet 

 thick, is composed of irregularly bedded clays and clayey sand- 

 stones. The coals are thin and of indefinite extent. A section ob- 

 tained at the junction of the Machariva and Sher Rivers and ex- 

 tending 150 yards, illustrates the conditions: 



(i) Sandstone not measured; (2) good coal, 3 inches; (3) soft 

 sandstone, 3 feet ; (4) coal seam, consisting of black micaceous shale, 

 6 inches, coal 2 feet, shaly coal, 6 inches, in all 3 feet; (5) hard 

 sandstone, 3 feet; (6) blue clay, 4 feet. The black shale of (4) is 

 cut out quickly by (3) and the shaly coal of (4) disappears within 

 a few feet, while (2) and (3) are replaced with clay before the end 

 of the exposure has been reached. Glossopteris is wanting in the 

 Upper Damuda, its place being taken by cycads. The coal seams 

 are wholly unimportant. 



The Talchir beds in the Thilniille coal field of Serguja have a 

 thin seam of coal ; but as a rule this formation is distinguished by 

 absence of coal and even of carbonaceous shale. The Kharharbari 

 coal group was included originally in the Barakar, but it was placed 

 in Talchir by Medlicott and Blanford^^ because of the intimate rela- 

 tion of the flora. 



Li studying reports on the several coal fields one cannot fail to 

 be impressed by the thinning of Raniganj, Barakar and Talchir from 



^'^ J. G. Medlicott, " On the Geological Structure of the Central Portion 

 of the Narbudda District," Memoirs, Vol. XIII., 1877, pp. 155-248. 



18 H. B. Medlicott and W. T. Blanford, "Geology of India," Calcutta, 

 1S79, pp. 109-112. 



