THE COUNTRY EAST, ETC. 165 



to the east and continue from thence along the valley of the Son 

 till they are finally hidden by the Gangetic alluvium. 



East of Gurdah the lower Vindhyan boundary trends southwards 



Country east of Gurdah before turning a generally east-and-west 

 and Agon. course. The scarp of the upper Vindhyans 



follows a similar course about 6 to 8 miles east of the lower Vin- 

 dhyan boundary, exposing a large area of the rocks of this series 

 between Kajrahat (Kujrahut), Agori (Agoree Khas), and Markundi 

 (Murkoondee). 



The lower boundary has been mapped by Mr. Vredenburg in detail 

 on the accurate maps now available. He found the limestone of the 

 basal stage everywhere well developed and overlying the basal conglo- 

 merates, except for a short distance in the valley of the Rer (Rehund) 

 river where the limestone is in direct contact with the transition. 

 Overlying the limestone come the beds of the porcellanite stage, 

 which form a number of low hills about Beldaha (Bildeh) and 

 Bauradih (Bowradeeh). To the east the ground is thickly covered 

 with recent deposits, the only exposures west of the Ghaghar (Ghagar) 

 being two small groups of low hills west of Markundi and north-east 

 of Salkhan (Sulkhun), which will be referred to further on. 



The porcellanites are again seen in the bed of the Son at Chopan 

 and can be traced thence eastwards. East of Kota there are several 

 exposures, by the roadside, of a conglomerate, similar to that seen 

 north of Khaira, in which the pebbles are of a porcellanite like those 

 found in this stage, imbedded in a matrix of similar type. 



In the Ghaghar at Markundi there is an extensive exposure of 



blue limestone dipping east-north-east, and to the 

 Limestone in the Ghaghar. 



east of this numerous exposures of shales with 



large rounded black calcareous concretions, the typical rock of the 

 upper Kheinjua stage, followed by bedded limestones of the Rohtas. 

 The exposure of Rohtas beds is fairly continuous though much 

 less than the normal thickness round the edge of the Kaimur sand- 

 stone, but west of the Markundi ghat (Aikpowah ghat) the upper 



( 'f>5 ) 



