472 Reviews — Geological Survey of India. 



I immediately published 1 a retractation of my error ; maintaining at 

 the same time, upon what I held to be ample collateral evidence, that 

 my view of the boundary was still essentially correct. "With such an 

 awful warning before him, Mr. Middlemiss was not likely to fall 

 into the same mistake ; indeed, the number and extent of the sections 

 he describes and figures, from widely distant localities, showing 

 original unconformable contact of this kind, leave no room for such 

 a supposition. At other points along the same continuous boundary 

 the contact is of the type so usual in this region — a steep plane with 

 the older rocks overhanging the newer, sometimes in apparent con- 

 formable sequence and each in normal order, the middle limb of the 

 folded flexure having been removed by overthrust. It is quite clear 

 that a common phase of this action may be a complete simulation 

 of a fault, normal or reversed, by the simple tilting of a denuded 

 face of the upper limb of the flexure after the deposition of newer 

 rocks against it, instances of which are given in Nos. I. and II. of the 

 sections under notice. The fault at Jirinjala in Section V. seems 

 uncalled for. Altogether, to speak of those boundaries, without 

 qualification, as faults, is to ignore their primary and most interest- 

 ing character. When in a continuous sequence of strata a folded 

 flexure occurs, with fracture and overthrust, the plane of contact 

 is a fault in the full sense of the word ; but to describe the main 

 boundary of the sub-Himalayan zone as a great fault is to open the 

 door for the very blunder that Mr. Middlemiss has deplored. This is 

 quite an ancient bone of contention with me. 2 I had expected to 

 find some reflections by Mr. Middlemiss on the lines suggested by 

 Mr. R. D. Oldham, in 1885, 3 that under the conditions supposed 

 there must have been for every stage a fringing zone of boulder 

 deposits, like the modern bhabar, of which the outer Siwalik con- 

 glomerates are the next preceding representative ; and, that judging 

 by analogy, the unrepresented bhabar deposits corresponding to the 

 Nahan sandstone must have extended about twelve miles north of 

 the present main boundary. 



The "one minor discrepancy" noticed at page 111 between my 

 work and his own, regarding a fourth possible sub-Himalayan group, 

 disappears at once with the recognition of the Siwalik sand-rock 

 on the north of the Kearda-Dehra dun. Again, at page 124, an 

 alternative view is mistaken for the one I finally adopted — that 

 elsewhere in the neighbourhood there is completely conformable 

 sequence between strata that are strongly discordant along the lines 

 of upheaval. At page 32, in his remarks on the main boundary, 

 Mr. Middlemiss may have forgotten that at one spot, not in his 

 area, where the Satlej crosses that boundary, the Subathu beds of 

 the Sirmur area pass continuously, by a narrow band, into the sub- 

 Himalayan zone, and there the Nummulitic beds and what may be 

 Nahans are in normal succession. In that direction, in Kangra 

 and Jamu, a much fuller subdivision of the sub-Himalayan system 



1 Records, vol. xiv. p. 169. 



2 Geol. Mag. 1869, p. 341 ; 1870, p. 473. 



3 Records, vol. xviii. p. 110. 



