44 MALLET, VINDHYAX SERIES. 



scries. Wide sheets of rock are frequently found with very slight 

 dip when a short abrupt bend is come upon^ the beds within a few 

 paces resuming their usual arrangement. In other places the strata form 

 a series of undulating anti-and syn-clinals, or the whole may be locally 

 crushed up in confusion. The axes of contortion are generally, when 

 considerable, marked by lines of breceiation. The breccia is different 

 in aspect from that of the older rocks, exhibiting a less complete 

 mineralization of the mass, and retaining the appearance of infiltration, 

 with many half-filled cavities. The cementing material is silica or lime, 

 the latter when the crush is amongst calcareous rocks. In consequence 

 of the decreasing dip from south to north, which is more marked in the 

 upper part of the valley, the higher members of the series generally 

 occupy a disproportionately large area. 



It is difficult to arrive at any very reliable estimate of the total 

 Thickness. thickness of the lower Vindhyans on account of 



their disturbed state and the want of good veirtical 

 sections amongst the bottom beds ; but allowing for such elements of 

 uncertainty, it seems that we are not likely to err very grossly in assign- 

 ing to them a thickness of 3,000 feet in the region east of the Rehund. 



Every consideration, physical, stratigraphical and lithological, sup- 

 ports the conclusion that the ' Semri ^ rocks of Bundelkund are the 

 same series as the ^ lower Vindhyans^ of the Sone vaUey. The same 

 certainty, however, no longer obtains when we descend to the sub-divisions 

 of the series and attempt to correlate those of each locality. Such 

 indeed can hardly be expected when we remember the distance between 

 the northern and southern outcrops and the vagueness of many of the 

 sub-divisions in either one of them. In both districts we find a con- 

 siderable development of sandstone at the base of the series and the 

 most important limestone* near the top, but it would be unsafe to assert 



* Memoirs, Geol. Surv., India, Vol. II, p. 6. 



( U ) 



