NERBUDDA DISTRICT. 193 



these escarpments, wherever the talus admifis of his making the ex- 

 amination, but very few indeed can be traced into the Mahadevas. The 

 rare exceptions which exist are insufficient to hinder the conviction 

 that the vast majority (at all events) of the dykes which cut up 

 the lower Damuda rocks were intruded prior to the Mahadeva period 

 and underwent denudation in common with those rocks. 



This belief is strengthened by the explanation it affords of the vast 

 quantity of trap detritus found in many of the 



Dykes of the upper 



Damudas do not run up Mahadeva conglomerates. JNow, although the up- 



into the Mahadevas. . . _ _ 



per Damudas are certainly far more tree from 



Trap Dykes than the lower Damudas, still several sections show dykes 



cutting them, and not passing up through the massive Mahadeva 



rocks above. Near Monighat village (already mentioned) the Hurd 



exposes beds so circumstanced, and in the Slier river about a mile above 



the measured section given L (P a g e 1^7,) two fine cases may be observed; 



in each of which a dyke several feet broad cuts the plant-bearing shales, 



and both it and they are overlaid by a thick mass of sandstone which is 



not pierced by the dyke, nor visibly altered at the contact, or rather, 



near it ; for the absolute contact cannot in either case be observed. In the 



Machiriva again precisely the same thing occurs. 



It may here be remarked that no case satisfactorily proving interstra- 



No contemporaneous Nation of any of the sandstones with trap has 

 interstratifiedtrap. been observed in this district This holds good 



for the lower and upper Damuda formations as well as for the Mahadeva, 

 with which we are at present more immediately concerned. 



The very slight amount of chemical change produced in the sandstone, 



Pseudo case of inter- b ? the traded rock, often might lead the observer 

 stratification. to m j sta k e for interstratification, the intrusion of 



trap between two beds of sandstone especially where the termination 

 or thinning out of the wedge shaped mass is not exposed. But it has 

 invariably been found in such instances, that a careful examination has 



