STRATIGRAPHY. 23 



is in the small development of the limestones of the Rohtas stage 

 near Markundi, but in this case it must be remembered that the dis- 

 tance is measured along, while elsewhere it is measured across, the 

 strike, and the cases are consequently not strictly comparable. 



The rocks of the upper Vindhyans in the main area of their 

 exposure were not specially examined during 



Upper Vindhyan series. 



the late survey, and so far as they are con- 

 cerned there is nothing to add to the statements in Mr. Mallet's 

 memoir. A few outliers north of the Son present no special features 

 of interest, the type of rock and the relation to the lower Vindhyans 

 is the same as in the adjacent Kaimur scarp. 



South of the Son, however, there area series of outliers which can- 

 not be ascribed to any other age than upper 



Outliers south of the Son. ... „ ~ . . „ ,. . 



Vindhyan. Omitting small outliers there are 

 three principal ones which occur along the zone of structural depres- 

 sion already referred to. In each case the outlier occupies high ground 

 and is usually scarped round its edge, owing to the resisting power of 

 the rocks of which it is composed, as compared with the more readily 

 decomposed schists on which it rests. The rock differs considerably 

 from that of the Kaimur or any of the overlying series of the upper 

 Vindhyans in that it frequently contains pebbles and even boulders 

 of a foot in diameter, composed of quartz or jasper. In some places 

 the abundance of red jasper pebbles derived from the Bijawars gives 

 it an appearance very like that of the Kaimur conglomerate as 

 described by Mr. Medlicott. 1 



The sandstones of the upper Vindhyans, on the other hand, are 

 remarkable for the absence of pebbles. Mr. Mallet records the 

 occurrence of pebbles at the base of the Kaimur sandstone near 

 Badanpur, 2 and to the east in Mirzapur, fragments of chert, appar- 

 ently derived from the lower Vindhyans, are found in the lower sand- 

 stone of the Kaimur stage. With these exceptions not a single 

 pebble or fragment of larger size than can be described as coarse sand 



1 Mem., Geol. Surv. Ind., Vol. II., p. 28. 

 » Mem., Geol. Surv. Ind., Vol. VII., p. 55. 



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