MAHADEVA SERIES. 4 7 



and easily defined north and south limits. Hocks which it is believed 

 belong to the same ag-e do^ indeed, occur in the Rajmahal hills and in 

 the Bisrampur field in Sirguja, but these are localities so far removed 

 from the tract of country under consideration that they may for the 

 moment be disregarded. The fact then to be accounted for is the 

 Limits of zone of dis- Occurrence of these Mahadevas along a zone of 

 ti-ibution. , country 240 miles long and from 3 to 12 miles 



wide, this maximum width being attained in but one place in the 

 Karanpura field, which occupies about the centre of the whole length. 

 Otherwise, the distribution may be indicated by saying that, exceptiuo- 

 the areas in the Raniganj field, which are slightly to the south, it is con- 

 fined within the 23° 40' and 23° 50' parallels of north latitude. 



"We have evidence, afforded by the present varied elevations of the 



Cause of the limita- ^oal measure deposits, and the frequent recurrence of 

 *^°°- great lines of east and west faulting in the Damuda 



valley and more western coal fields, that great disruption of the orio-in- 

 ally much more extensive and continuous deposits took place f and that 

 while the broken and disturbed areas raised to the higher elevation 

 have been much denuded, the principal coal fields have been preserved in 

 consequence of their being protected in a trough produced perhaps by a 

 fold in conjunction with the faulting. 



In this trough or valley a huge sluggish river, with little power for 

 excavating, may have flowed and gradually deposited the sand and gravel 

 which has formed the Mahadeva rocks. 



The past history of the Panchet group has not been alluded to, but 



Past lustorv of the ^^ seems probable that it is the same as that of the 



Panchets. older groups, though both it and the E-anigauj and 



Ironstone Shale group have this in common with the Mahadevas, that 



their distribution is restricted to a definite zone. There is, however, a 



* On a first glance at the map the clear definition of the valleys in which the Aurunga 

 and Hutar fields respectively lie suggests that these were the original limits of deposition, 

 but examination rather tends in the direction of showing that these bounding highlands are 

 due to subsequent upheaval. 



( 47 ) 



