GENERAL GEOLOGY. 17 



materially in placing approximately in their position in the geological 

 scale the older groups of rocks, including the coal-measures (Damudas). 



Thus for many years the eyes of Indian Geologists have been 

 directed towards the Rajmehal hills as classic ground for the study of 

 Indian Geology. 



The rock-groups occurring in the area under description are in 

 descending order as follows ; — 



Alluvium. 

 Laterite. 

 Gondwana System. 



Rajmehal Group. 



Lubrajpur Group. 



Bardhar Group (Bamuda Series). 



Talchir Group. 

 Metamorphic Series. 



The Gondwana system is very incomplete in this area. Even the 

 Damuda series of the lower Gondwanas, so largely developed in the 

 adjoining Raniganj field, is here represented only by the Bar&kar group. 

 Between the periods of deposition of the above successive groups, it 

 may fairly be asserted that we have full and satisfactory evidence that 

 the surface was subject to considerable denuding action, which in some 

 instances was accompanied by a certain, but not excessive, amount of 

 disturbance. 



It should be remarked that the overlap, frequent eases of which 

 will be found enumerated in the following pages, does not necessarily 

 imply that there is absolute unconformity of the beds where it occurs. 

 Many cases probably, and some certainly, are simply due to great origi- 

 nal unevenness of the metamorphic rocks upon which the sedimentary 

 beds were deposited. In some places this surface was hollowed into 

 basins, in others, hills, ranges, and small plateaus rose above the general 

 level. Against the sloping faces so formed, the sedimentary rocks were 



c ( 171 ) 



