COUNTRY NORTH OF THE SON. 



127 



lower Vindhyan rocks. The two, however, are exposed in close prox- 

 imity to each other in circumstances which preclude the idea of their 

 being of the same age. 



Fig. 10. Section on south face of Dadri hill, west of Tarka. 

 /, Transition; 2, lower Vindhyan ; 3, upper Vindhyan. 



About a mile to a mile and a half west of Tarka the bottom 

 conglomerate of the lower Vindhyans is exposed with a dip to the 

 southwards of about 20°, resting on transition quartzites of Bijawar 

 type, which dip northwards at 6o°, or at nearly a right angle to the 

 lower Vindhyans. The contact rock is an angular breccia of talus 

 debris. On the spurs the exposure of lower Vindhyans runs up the 

 slope, and on some of the spurs the narrow gap between them and 

 the edge of the sandstone of the plateau is so thickly covered with 

 debris of the latter that it would not be difficult to regard the two as 

 continuous with each other. On other spurs, however, the gap 

 between the two is comparatively clear of debris and the bottom bed 

 of the lower Vindhyans is exposed within 300 yards of the'sandstones 

 of the plateau, the two contrasting in character most markedly. 



The lower Vindhyan basement beds consist of an angular breccia 

 overlaid by pebbly sandstone, and this again by impure sandstones 

 without pebbles. The rocks of the plateau have no basal breccia 

 such as the contact rock of the lower Vindhyans. There is a much 

 greater thickness of coarse-grained beds and the rock itself is whiter 

 and cleaner, has a softer and more grating surface, and contains a 

 larger number of pebbles, though of smaller size, than the neighbouring 

 sandstone of lower Vindhyan age. The contrast is too great to allow 

 of the two being of the same age, and the comparatively moderate 



( 127 ) 



