MALLET, VINDIIYAN SERIES. 49 



succession by the older sub-divisions. This basin-form is, it seems, 

 intimately connected with the original conditions and area of deposi- 

 tion, which question with regard to the northern side has been dis- 

 cussed in a previous volimie of the memoirs.'^ The boundaries which are 

 nearly everywhere natural, are sharply defined, the outHers, although 

 pretty numerous, bemg small and close to the main boundary. The 

 cliief regions of faulted junctions are the Nerbudda valley, and that 

 south-west from Agra. As a whole, the formation, notwithstanding its 

 antiquity, is not much altered. The lower sandstones, however, are not 

 unfrequently more or less vitrified, or even converted almost into quart- 

 zite, as in the Dhar forest ; and the shales more or less indurated : the 

 upper members, the Bundairs, seldom betray any sign of change. 



The formations which overlie the Vindhyans are of comparatively 

 recent date. Thousands of square miles are obscured by trap, but the 

 great Indian carboniferous series, intermediate in age, are nowhere found 

 in superposition. Such evidently never existed there. The unaltered 

 condition of the Bundairs would seem to indicate that they never have 

 been subjected to great superincumbent pressure which has more or 

 less aflfected the lower groups of the formation. 



(a). — Kymore Group. 

 The Kymores attain their greatest extension, horizontally and 



vertically, at the eastern end of the Vindhyan 



Lower Kymores. '' 



area, and it is here especially that the lower sub- 

 group is developed, which, however, is of small importance compared 

 to the upper. It may be studied best along the course of the Ghagur 

 near Bijigurh fort, the broad shallow valley of which has been scooped 

 out of the shales, which crop out in the scarp at either side, and on 

 the flanks of the imposing hill from which they derive their name. 

 Fine sections are also obtainable in the Doorgowi;ee valley. South-east 



. ' * VoL II, p. 57. 



( 49 ) 



