PHYSICAL GEOGRAPHY, 4$ 



more powerful Son, but the erosion is so far behind that of the main 

 valley that this supposition is unlikely. If on the other hand the 

 Ghagar valley is altogether newer than, and formed by cutting back 

 from, the valley of the Son, the appearance of recent and active 

 erosion which it presents would be in keeping with what should be 

 expected. 



The elucidation of the origin of the Ghagar valley is complicated 

 by the fact that there is no present indication of a cutting back of 

 its head waters on the plain above the Kaimur scarp. In the case of 

 the Adh, the next largest and only srightly smaller tributary from the 

 north, the evidence is complete. 



In Rewah territory it will be seen from the map that the Kaimur 

 range is double, consisting of two scarps, of 



The Adh valleys* . . 4 , 



which the southern is formed by the Kaimur 

 sandstone and the northern by the upper Rewah sandstone, the low 

 ground between being occupied by the less resistant shales and sand- 

 stones of the lower part of the Rewah series. From about Long. 82 

 E. the depression is occupied by the strike valley of the Adh river 

 draining eastwards and ultimately to the Ganges. From the water- 

 shed at the head of this valley another stream, also known as 

 the Adh, flows westwards for about ten miles, when it is joined by 

 a stream which has flowed eastwards for nearly the same distance 

 through a similar valley, and the combined waters break southwards 

 in a precipitous-sided gorge, through the Kaimur scarp and as the 

 Narkuni (Narkooi) Nadi flows into the Son. 



At the watershed between the eastern and western Adh, there 

 is a broad open valley, filled with recent deposits, whose surface 

 has been a good deal eroded and rendered irregular. To the north 

 is a small valley draining from the Rewah scarp which appears to 

 have formerly drained into the eastern Adh, but to have been di- 

 verted into the western. Leaving this open plain and descending the 

 western Adh it is found that the valley bottom soon drops some- 

 what rapidly and the stream-bed takes on an aspect of active erosion. 

 The side valleys too seem to have recently been deepened, for a 

 E ( 49 ) 



