352 On the rocks ofthe Damúda group. [No. 4. 



On the rocks ofthe Damúda group, and their associates in Eastem 

 and Central India, as illustrated hy the re-examination ofthe Rctni- 

 ganj field. — By W. T. Blanford, Usq. Geological Survey of India* 



One of the most interesting problems in Indian Geology is the 

 question of the age and mutual relations of the rocks containing eoal 

 in Bengal and Orissa. The fossils from the first named locality have 

 long attracted notice in consequence of the great divergence shewn 

 by them from European types of carboniferous vegetation, and of 

 their identity with those from beds, also containing eoal, in Australia. 

 But these fossils being entirely vegetable, and fossil plants not having 

 attracted, until very recently, the attention they deserved, except in 

 the case of the true carboniferous flora of Europe and America, very 

 little progress had been made towards ascertaining the geological 

 relations of the Indian eoal fields, until the commencement of the 

 work of the G-eological Survey of Mr. Williams. They were almost 

 universally massed together as representativos of the carboniferous 

 era, and the details of their geology were utterly unknown. They 

 had not even received the attention which had been devoted to the 

 rocks of Central, Western and Southern India. 



Mr. Williams directed his attention rather to the economical than 

 to the scientific questions piesented to him, and he appears, in his exa- 

 mination of the Rániganj field, not only to have accepted the idea 

 of the rock« being of true carboniferous age, but to have supposed 

 that he found in the several beds composing them, representativos of 

 the subdivisions recognized in Great Britain. But his observations on 

 the geological relations of the beds among themselves are generally 

 careful and accurate, his map is singularly correct, considering the 

 very grave difneulties under which he worked, and although, partly 

 perhaps owing to the small área which carne under his observation, 

 many essential circumstances escaped his notice, his accurate and 

 trustworthy descriptions have since proved most valuable in shewing 

 the relations of the rocks he surveyed to others which have since 

 been examined. 



The only other detailed geological observations are contained in 



