1S60.] On the rocks ofthe Damúda group. 355 



Rajmahál hills, besides their occurrence in the fields of Rániganj and 

 Rámghar. 



The Damúda series, thus named from its extensive development on 

 thebanks ofthe river Damúda, comprises, with perhaps one exception, 

 all those rocks from which coal has been obtained in Bengal ; the 

 coal bearing rocks of the Himalaya, Khasi hills and Burma being, 

 however, distinct. This series is divided in the Rániganj field by a 

 mass of black shales, containing beds of clay ironstone, and attaining 

 a total thiekness of about 1,500 feet. There is evidence of uncon- 

 formity between these shales and the Lower Damúdas, but none is 

 clearly made out between them and the upper series or Rániganj beds, 

 with which they are in consequence classed. 



The Upper Damúdas of Rániganj must be carefully distinguished 

 from those beds in Central India which have been called Upper 

 Damúdas,* Mem. Geol. Survey of India, Vol II. pp. 176, 312. 

 The Rániganj beds diífer from the Lower Damúdas in mineral 

 character, and also slightly, so far as is at present known, in fossil 

 remains. The upper beds consist mainly of very thick false bedded 

 sandstones, with seams of coal frequently continuous over considerable 

 áreas. The lower beds are much coarser and more conglomeritic, and 

 are rarely false-bedded ; their coal seams are mimerous, but very vari- 

 able in quality, and frequently thin out, or change into shale, or 

 even sandstone, within very short dist anees. 



The most characteristic fossil distinction between the two groups 

 consists in the abundance of a species of plant referred by Mr. 

 Oldham to Schizonema, in the upper división, which has not been 

 found in the lower. No animal remains have as yet been discovered 

 in the Damúda beds. 



The upper or Rániganj series is not known to be represented 

 beyond the Damúda field. The lower group is also found in Orissa, 

 and along the Western side of the Rajmahál hills. The superiority 

 of the coal of Rániganj is perhaps partly explained by the circum- 



* This ñame was given for good geological reasons, as will be seen by reference 

 to Vol. II. of the Memoirs ofthe Geological Survey. It has however proved an 

 unfortunate appellation, as it conveys an incorrect idea of the relations of the 

 beds, which contain a flora completely distinct from that of the true Damúdas. 

 see Mem. Geol. Survey, Vol II. p. 176. 



3 A 



