STRATIGRAPHY. 7 



is principally remarkable for the conspicuous " reaction rims" sur- 

 rounding the olivine crystals. 



Between the intrusion of the granite and the formation of the 

 next successive sedimentary series ensued a long 



Interval succeeding the ,,.-,, • t. u *.u^ Uf^- 



granitic intrusions. period, possibly bridged over in part Dy tne later 

 conglomerates mapped as transitions, though, as has been pointed 

 out, there is no evidence of their age relative to the granites. During 

 this period there was evidently a good deal of disturbance of the beds, 

 as is evidenced by the strong divergence of dip between the Bijawar 

 and the unconformable lower Vindhyan beds on some sections, and 

 one of the leading structural features of the region was marked 

 out. 



It will be noticed that the crystalline rocks are exposed in 

 two areas respectively north and south of the 



Zone of depression. m \ 



band of transition rocks, and as the former must 

 have consolidated at a considerable depth below the surface, this 

 implies a greater structural elevation of the areas they now occupy 

 than of the intervening belt. In other words, the transition rocks lie 

 in a great synclinal depression or synclinorium, and the fact that 

 the crystallines are unconformably covered by the lower Vindhyans 

 shows that they must have been raised and laid bare by denuda- 

 tion even at the early period of the commencement of the Vindhyan 

 epoch. 



The synclinal depression formed at that period was continued 

 and increased during succeeding geological ages, as is shown by 

 the line of outlines of newer rocks which runs through the transition 

 area. The axis of elevation lying north of this line is continued 

 into the Vindhyan rocks towards Sarsi on the one hand and Bijai- 

 garh on the other, and, as will be shown later on, was apparently 

 marked by an actual elevation of the surface level even in lower 

 Vindhyan times. 



Following on that undefined collection of more or less metamor- 



jungei or Red Shale Prosed sedimentary series, which is classed as 



senes " transition, comes tne oldest which can be 



( 7 ) 



