28 MIDDLEMISS: PHYSICAL GEOLOGY OF SUB-HIMALAYA. 



band is not quite a natural one, so that the thickness there should 

 probably be a little more. On the other hand, the conglomerate, 

 which begins to thin at the R^mganga, dwindles down to a scarcely 

 recognisable bed in the Kotri N. Its northern edge is, however, a 

 fault, though, as will be shown later on, it is improbable the conglo- 

 merate here was ever very thick. Should it be found true that the 

 thickness of the sand-rock varies inversely as that of the conglo- 

 merate, we should probably have to regard the upper part of the 

 former, in one locality, as contemporaneous with the lower part of 

 the latter elsewhere. 



The Lower Siwalik, or Nahan beds, as already mentioned, may be 



called sandstones ; for they are, as a whole, much 

 Nahan sandstone. 



more indurated than the rocks of the sand-rock 



stage, although the two merge into one another conformably. The 



Nahan sandstone is generally of darker colour than the sand-rock, 



brownish and greenish-brown tints prevailing, with sometimes a 



bluish-grey. It is very micaceous, and occasionally felspathic. It is 



never so purely silicious as the sand-rock, but contains more earthy 



and secondary ferruginous products. Purple, dark reddish brown and 



greenish shales, finely laminated, are interbedded with it, especially 



at the lower horizons. It is possible that this preponderance of red 



shales in the lower parts indicates an incomplete passage into the 



uppermost Sirmurs ; but such a passage has never been actually 



proved in this region : that is to say, the lowermost Nahans never 



show the nummulitics underlying them in a normal section. There 



are some conglomerates similar to the clay conglomerates of the 



sand-rock, but they are generally more compact and more firmly 



aggregated. In the upper horizons there are also some concretionary 



layers of the same nature as, but less distinct than, those in the stage 



above. There are irony bands in some of the lower purple shales, 



which near Dechauri swell out into considerable beds of brown 



hematite. This was once worked, and smelted along with the Ram- 



garh iron ore brought down from the higher hills for the purpose. 



The absence of coal in the neighbourhood has rendered this unprofit- 



( 86 ) 



