120 GEOLOGY OF THE SON VALLEY, ETC. 



The red shale series, which is not seen in the Samdin, comes in 



a short distance to the east, the exposure broad- 

 Red shale series. . . ., . . . 



ening out rapidly, attaining a width of nearly 



ij mile near Nakni. The bottom conglomerate is cut out in places 



by faults running nearly east and west, but east of the Nakni stream 



it is continuous, attaining a considerable thickness and forming high 



prominent hills about a couple of miles west of the Banas. 



The beds above the bottom conglomerate are of the normal type 

 of red and green shales. Near the Banas the uppermost beds seen 

 are greenish and schistose beds containing numerous grains of sand 

 scattered through the argillaceous matrix. 



The crystalline rocks immediately south of the main exposure of 

 the lower Vindhyans are very badly exposed. 



Crystalline rock. J # J # J r 



Owing to the readiness with which they decom- 

 pose they have formed an area of low ground surrounded by the 

 hills of the transitions on the south and the ridge of lower Vindhyan 

 basal conglomerate on the north. This low ground is deeply covered 

 with an accumulation of dust deposits and no exposures are seen 

 except in the stream-beds. 



East of Chachai the junction of the granite and transition schists 

 is seen in the bed of the Samdin, the gneissose granite forming 

 strings and tongues penetrating the schists. Along the junction 

 lines in some parts fragments of schist are included in the granite, 

 and the foliation of the schists is better developed in the immediate 

 neighbourhood of the contact. At other parts the contact is abrupt 

 and clean-cut, these being due to displacements to which the rock has 

 been subjected after the intrusion and solidification of the granite. 



In the bed of the Son the granite is freely exposed, and it is seen 

 that the basic dykes which penetrate it cannot be traced continuously 

 for any distance, being cut off and displaced by dislocations of the 

 rock 



( «*o ) 



