1886.] of the Pimjah and its Elvers. 325 



alluvium at a lower level than that of the river where it passes through 

 the gap. It is difficult to give anj satisfactory explanation of this 

 feature if we suppose the Indus to be the only river that ever flowed m 

 this region, but I hope to shew that there are both historical and geo- 

 graphical indications of the former existence of a river which flowed 

 to the Ran of Kach, independent of the Indus, and, if we admit its 

 existence, the following hypothesis may he offered as a possible explana- 

 tion of the existing peculiarity in the course of the Indus. 



In former times, the Indus wandered over the plain which surrounds 

 the Khairpur hills, raising the level of the soil on either bank till it 

 broke away into the low ground on one side or the other, and so by 

 degrees raising the level of every part ; during the latest phase of this 

 process, previous to the origin of the existing conditions, it flowed east 

 of its present course and, having raised the level of the ground there, 

 wandered away westwards ; by this time the surface of the alluvium 

 had been raised till it was level with a gap in the Khairpur hills at 

 Rohri, and, as the alluvium south of the ridge would probably be at a 

 considerably lower level than on the north side, the waters of the Indus, 

 having once found an outlet through this gap, would soon establish a 

 permanent course for themselves. If then we assume that the other 

 river instead of depositing silt and raising the level of its alluvium was 

 an eroding stream, we may suppose that it gradually worked westwards 

 till it reached the present situation of the Eastern Narra and excavated 

 that channel : the flood waters from the Indus would smooth off the 

 slope between them, and, had the process continued, there can be little 

 doubt that the Indus would soon have broken away into this low lying 

 channel, had not the other river, owing to a change of course in its upper 

 reaches, dried up before this happened. It may seem strange that two 

 rivers should have flowed so close to each other under such different 

 conditions, but it must be remembered that, if the second river was 

 small in comparison with the Indus, it may well have deposited all its 

 silt higher up its course, and consequently have had none to deposit 

 when it reached the latitude of Rohri. 



So far I have merely proposed a possible hypothesis to account 

 for the known peculiarity of the course of the Indus, but I hope to be 

 able to shew that there is both historical and geographical evidence 

 of the former existence of this second river. 



§ 3. The commonly accepted opinion that the Eastern Narra marks 

 the former course of the Indus is no doubt due to a prevalent tradition to 

 that effect among the natives of the country ; but it must be borne in 

 mind that these traditions often arise from an endeavour to explain 



