GENERAL CONSIDERATIONS. 51 



Jherria, the Karharbari, the Deoghar, and the Raniganj fields are all 

 faced by high ground of metamorphie rocks at varying distances from 

 their present boundaries. In the region of Palamaiin, and in the valleys 

 of Behar, where the lower series of the coal-measures occurs, there is this 

 constant relation of high level metamorphics and low level coal rocks. 

 Observing this relation, it remains to enquire whether it be due to sink- 

 ing of the floor of the coal-measures within the limits of the metamorphie 

 high ground, or whether the coal-measures were deposited approximately 

 within their present boundaries. If the latter supposition be correct, it 

 of course fixes the minimum age of the sculpturing of the Hazaribagh 

 and Chota-Nagpiir table-lands. 



In the absence of proof of the existence of coal-measures on any 

 of the high-lands, the tendency of the evidence that the rocks afforded 

 within the limits mentioned above would have been to prove that, 

 although the areas of the coal-fields have been modified by faulting and 

 denudation, still their position relative to the high ground which limits 

 them was due not so much to any throws, as to their original deposition 

 in the low-lying ground which they occupy, but the occurrence of coal- 

 measures on the Hazaribagh table-land, at a very much higher level 

 than those of the Damuda valley, sets the question at rest, by manifest- 

 ing that considerable displacement of the coal rocks has taken place 

 since their deposition. 



This circumstance plunges us into the region of speculation regard- 

 ing the original extension of the coal-measures, but, on the other hand, 

 it affords us a clear light by which to interpret the nature of the 

 boundaries. 



Boundaries— faults. — The first consideration will be the relation of 

 the different groups as bearing upon faults. In almost all these coal 

 basins, the southern boundary is indicated as being a principal fault. 

 This is based upon the fact that the rocks of the sedimentary series, 

 which are found in contact with the metamorphie rocks encircling them^ 



( 335 ) 



