NERBUDDA DISTRICT. 217 



§ 9. The Trap Rocks. 



The boundary of the great trap covered area to the south having 

 Trap area little ex- been ta ^ en as a convenient limit to work up to, 

 p • less time was devoted to an examination of the 



rocks included within this group, although offering many and most in- 

 teresting peculiarities, than to others. 



Although under the head of the Trap it is meant only to include the 



rocks of the great overflowing Basalt period, yet 

 Trap of different age. 



it may be well here to direct attention to some 



rocks very similar in lithological characters to parts of that basalt for- 

 mation, though distinct from it in age. Trap is 

 Proof of this. 



every where to be seen overlying, and trap dykes 



frequently disturb the Lameta beds ; the basaltic epoque was in short 

 certainly subsequent to the consolidation of the rocks of that series. 

 But the " Mahadeva" conglomerate is in places almost altogether made up 

 of trap detritus, and it seems natural to refer this to the degradation of 

 the numerous dykes which traversed the Talcheer and lower Damuda 

 beds, prior to the formation of the Mahadeva Rocks. The lowest beds of 

 the Talcheer group however themselves contain fragments of trap, (see 

 Fig. 5, p. 152). In the Rawundeo section already figured and described, 

 the " Boulder Bed" is seen resting unconformably on some beds of crys- 

 tallised schists where these are traversed by a dyke (which does not pass 

 into the bed above) and one of the Boulders in this bed is a fragment in 

 which a piece of the dyke wall remains adhering to the greenstone. 

 We thus have good evidence of three periods of disturbance, when 

 Three Periods of trap { g nems ™ cks were intruded among the sedimenta- 

 mtrusion. ry deposits, 1st, one prior to the oldest Talcheer, 



2nd, one subsequent to the Lower Damudas and prior to the Mahadevas, 

 and 3rd, the great Basaltic period when all the overlying trap of this 

 country was poured out over the surface. 



