Il8 GEOLOGY OF THE SON VALLEY, ETC. 



shales and above them the porcellanite stage. As seen in 

 the bed of the Samdin these rocks were not immediately recognised, 

 being softer than usual with a larger proportion of green-coloured 

 beds and an intermixture of red shales. A short way to the east, 

 however, these rocks pass into the normal type of the stage. 



The porcellanites are overlaid by shales and sandstones, the 

 highest beds seen being purple sandstone, slightly calcareous with 

 ophitic calcite crystals of about one-eighth inch and occasionally 

 one-quarter inch diameter, whose cleavage faces show as glistening 

 patches on the fractured surface of the rock. 



The northern limit of the lower Vindhyans is a fault which brings 

 in transition schists, followed immediately by the basement bed of the 

 red shale series overlaid by the beds of this series, forming the 

 continuation of the outcrop which has been traced from the 

 neighbourhood of Marai. Where the bottom quartzite of this series 

 crosses the Samdin it takes a sudden bend to the north, the 

 quartzite having a northerly strike in the stream-bed. The line of 

 outcrop on the east of the Samdin is some 300 yards to the north of 

 the outcrop on the west, and the same displacement has occurred in 

 the fault bounding the lower Vindhyans. 



The northern boundary of the red shales is a fault, beyond 

 which the transition quartzites and phyllites 



Red shale series. 



continue to the boundary of the great expanse 

 of crystalline gneiss and granite in the Son. 



East of the Samdin the termination of the Marai exposure of the 

 red shale series takes the form of a number of isolated patches of the 

 basal conglomerate, sometimes associated with the overlying 

 red shales. These patches form low elongated ridges striking about 

 north-east by east, the dip being to the north-west. The structure 

 here is very complicated and could not be worked out in detail on 

 the somewhat imperfect map available. On the quarter-inch map 

 attached to this report the delineation has necessarily been purely 

 diagrammatical. 



( us ) 



