GENERAL CONSIDERATIONS. HI 



selves. The different bands of rocks, besides having strongly marked 

 characteristics whereby they may be recognised, actually pass from 

 one to the other of our working grounds (a proof of their sameness the 

 most complete possible). That being the case, it would be waste 

 of words to say more in enlargement of this truth. Beyond this, 

 there is really very little else to do in this connection. As already 

 stated, this work aims at being an extension of Mr. Medlicott's, and, 

 therefore, so long as our two classifications correspond, the chief 

 business of correlation is at an end. 



The advantages of larger maps have enabled me to mark, with a 

 separate colour, the M. Siwalik sand-rock, following Mr. R. D. 

 Oldham 1 in this; whereas Mr, Medlicott represented the U. and M. 

 Siwaliks by one tint on the map accompanying his memoir. 



There is only one minor point on which I think it at all likely 



Possible slight dis- that I may prove at variance with Mr. Medlicott, 

 crepancy. At page ^ Q f h j s memo i r he canvasses the 



possibility of a fourth group or rock stage, of lower horizon than the 

 Nahans, and of higher horizon than the Sabdthu. {N.B. — Sab^thu here 

 includes the whole of the Sirmurs, i.e., Kasauli, Dagshai, and Sabdthu 

 proper). I have never seen any reason in Garhw£l and Kumaun for 

 the creation of a fourth stage. On the other hand, I have taken as 

 the basis of my classification that the lowest rocks exposed south of 

 the main boundary be called Nahans. Of course, had a section 

 shewed nummulitic-bearing rocks in normal succession beneath 

 Nahans, this decision would have had to be modified and an arbitrary 

 line drawn between the two; but, until fossils had proved such a 

 succession, I thought it better to call the older rocks south of the 

 main boundary Nahans, although the presence of purple shales in 

 greater preponderance in the lowest beds seemed to indicate a 

 petrological change into deposits something resembling the upper- 

 most Sirmurs. I cannot but think that somewhere along the plain- 

 ward edge of the hills there will eventually be found a section 

 embracing nummulitics and Nahans in one normal succession, just as 

 1 See Rec, G. S. I., XXVII, p. 161. 



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