PHYSICAL GEOGRAPHY. 41 



If the map is examined it will be seen that on either side of the 



Encroachment on head WaterS ° f this streatX1 is aD ex P a nse of 



drainage area crystalline gneiss. On the one side is a tribu- 



tary of the Banas, on the other of the same stream which the 

 Kushmahar drainage ultimately joins, to flow into the Son near 

 Bhelki. Formerly the stream which flowed through, and carved out, 

 the gap north of Kushmahar must have been larger than it now is. 

 due to greater power It had, however, not the same power as the 

 on the west, combined waters of the Banas and the Son 



and the gap through which they flow was cut down faster 

 than that at Kushmahar. As a result the tributary of the Banas 

 which flowed from the east, had a steeper fall than that of the 

 Kushmahar stream, which flowed from the west, the valley of the 

 former was gradually lengthened by a cutting back of the watershed 

 and the drainage area of the head waters of the Kushmahar stream 

 reduced. 



Meanwhile this drainage area was being attacked on the other 



and to less resistance side > but for a different reason. On the east 



on the east. there is no large and powerful stream like the 



Banas, but it will be seen that the eastern branch of the combined 



waters, that called Eonar N. on the map, flows over the easily 



decomposed crystalline gneiss and crosses the boundary of the 



lower Vindhyans in a region where the basal conglomerates, as 



mentioned in Chapter VII., are thin and incapable of forming a 



pronounced ridge. Here we have less power than in the Banas, 



but very much less resistance to be overcome than by it, or by the 



Kushmahar stream. As a consequence this eastern branch has 



been able to lower its bed faster than the Kushmahar stream, 



and by cutting back its watershed to reduce the area of its drainage 



basin. The volume of the Kushmahar stream, and consequently 



its power, has thus been reduced by encroachment on its drainage ; 



it will no longer be able to lower the gap through the quartzite ridge 



at a rate that will enable it to preserve its individuality in opposition 



to the opponents which are attacking it on either side and the 



( 41 ) 



