GENERAL GEOLOGY OF THE AREA. 23 



of Burwar, I found in the Dhursot nullah the trap shown in fig. '2 

 (p. 25), beyond which the dip increases to the south or south-west, the 

 sandstone beds containing a few earthy beds of shales with the above 

 fossils. 



Though I have observed throughout the coal-field an apparent con- 

 formity of the Mahadevas with the older Gond- 



Probable overlap. 



wana rocks, it is yet probable that the former over- 

 lap the lower beds here and there. The nature of the jungle-covered 

 country, however, makes it extremely difficult to decide this point. Near 

 the south-eastern boundary of the field on the low ridge of metamoi-phics 

 separating the Tatapani field from the Bisrampur field, patches of coarse 

 reddish-brown grits and sandstones abound ; they form only a thin cover- 

 ing on the metamorphics, and are evidently only the remains of a vast 

 extent of Mahadeva rocks which once probably covered a great area, 

 connecting the various fields. 



Trap. 



I have certainly come across three varieties of trap rock in my 

 survey. A semi-metamorphic trap forms a dyke 



AllJGl'GCl urfip. 



of somewhat less than a mile in length, and 

 only some 20 yards wide in the mica schist south-east of Chura. Near 

 the dyke a disturbance is visible in the mica schist, the latter dipping 

 from it. The direction of the dyke is north-west to south-east. It is an 

 extremely dense variety, and almost resembles hornblendic rock. 



A basaltic rock caps nearly all the main gneiss plateau south of the 

 ^ , coal-field, and forms continuous sheets of perhaps 



Basalt caps on gneiss. ^ 



not more than 5 feet thick. Kemains of the trap 

 sheets are found on the top of all the plateaus wherever the original 

 surface has been preserved; on the lower hills, which evidently have 

 undergone extensive denudation, we miss these traps. On the tops of 

 the Lamti-pat and Gulgul-pat, fig. 1, pi. I, we find laterite associated 

 vdth the trap, but the exact connection was not observed, owing to the 

 dense vegetation covering the whole. 



( 151 ) 



