138 GEOLOGY OF THE SON VALLEY, ETC. 



up than the" last-mentioned exposure. Here the dip is 15 W. of 

 S. at 30° ; the gneiss is exposed a few yards to the north, but the 

 nature of the actual contact is not seen. The beds along the 

 boundary continue to consist of Mahadevas for a length of over half 

 a mile ; then a small basic dyke occurs in that same position. 



East of this dyke the rocks are again much concealed ; some 

 Barakar beds are seen dipping east at io°. The next rock exposed 

 belongs to the Talchir stage. The dip of the beds is 70 W. of 

 S. at 44 . The rocks exposed in the river-bed are laminated 

 micaceous sandy shales interbedded with a clayey coarse sandstone 

 of a deep greenish-blue colour, and containing a multitude of pebbles 

 varying from mere sand-grains up to a foot in diameter. Many of 

 these consist of gneiss similar to that exposed in the neighbourhood ; 

 the majority are derived from the Bijawars. Some pebble-beds consist 

 of a conglomerate partly formed of red jasper fragments, and are 

 consequently newer than the Bijawars, possibly Vindhyan. The ice- 

 scratched surfaces are conspicuous. 



Fig- I5« Section near Kachinar. 



We have here the three divisions of the Gondwanas brought inta 

 close proximity to one another, and the diagram section, Fig. 15, 

 illustrates the view which is taken of the nature of the boundary. 



The Talchirs are exposed only for a short distance along the 

 river-bed ; a little further east, higher up its course the Barakars 

 interbedded with carbonaceous shales once more make their appear- 

 ance. They dip 20 E. of N. at io°. 



Notwithstanding the great irregularities in the amount of dip, 



( 138 ) 



