January 28, 1892] NATURE 



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(iifficult to decide its exact limits. Native geographers and the 

 Paranic scriptures define the Himalayas as comprising only the 

 chain of snowy peaks at the head of the Ganges drainage. 

 Modern views generally limit the Himalayas to the system of 

 mountain ranges which extend between the Brahmaputra and 

 Indus rivers. Of course, structurally, the-;e ranges continue 

 beyond these boundaries, but there are distinct changes in the 

 features of the ranges which make these limits advisable. As 

 regards the lateral extension of the region, several views have 

 been formed ; but I consider it most convenient, and at the same 

 time more in accordance with the original significance of the 

 term, to call Himalayas only the system of ranges which fringe 

 the Tibetan highlands along its southern margin, a view which 

 is now most generally held. That part of the system in which 

 rise the headwaters of the Ganges drainage, and extending 

 north-westwards as far as the Sutlej gorge, I call here the 

 Central Himalayas, and within this area I divide the Central 

 ranges into (i) Northern range (watershed), and {2) Southern 

 range (line of highest peaks). 



Whilst the Southern range of the Central Himalayas is formed 

 chiefly of crystalline rocks, mostly gneissic with metam )rphic 

 schists, it is shown that the Northern range is almost entirely 

 omposed of a vast sequence of sedimentary strata, ranging from 

 the lowest palreozoic to tertiary and recent a^e. The detailed 

 description of these various formations I have given in the 

 preceding pages, and I will here only recapitulate the following 

 points. 



Immediately on the crystalline schists reposes an enormous 

 thickness of beds of varying lithological character, named 

 haimantas by me, which are sharply defined near its upper limit 

 by most characteristic red quartz shales, which form the base of 

 the richly fossiliferous lower Silurians. Structurally, this system 

 is very much more fully developed than the succeeding Silurians, 

 being in most sections more than double the thickness of the 

 latter. But the lower limit of the haimantas is obscure ; an 

 almo-;t perfect lithological passage may be traced from the 

 crystallines (vaikritas) into this system, both in the western and 

 easternmost sections described. 



One of the most characteristic amongst the various horizons 

 in this system is a great thickness of a coarse conglomerate or 

 boulder-bed, which in some sections alternates with slaty beds, 

 but is never entirely absent. This, in conjunction with the 

 ripple-marking which may be seen on nearly all the slaty beds of 

 the haimantas, indicates clearly that wfe must suppose the 

 ancient coast-limits of haimanta age to have been in close 

 proximity. The apparent overlap of haimantas on gneiss (Niti 

 area) is easily explained, if we suppose this system to have 

 been developed in this region as a littoral formation. It is 

 extremely probable that one of the earliest Himalayan dis- 

 turbances occurred immediately before haimanta times. 

 ; Lithological resemblance, not less than structural features, 

 point to the probability that a part at least of the slate series of 

 the Lower Himalayas are equivalents of the haimanta system of 

 the Central Himalayas. I believe even that some of the older 

 rocks, which immediately underlie the Vindhian group, may yet 

 be found to belong to the same age. It would thus follow that 

 the haimanta seas had extended not only over the greater part of 

 the present Himalayan area, but perhaps also as far south as 

 Central India. If so, the line of the Central Himalayas was 

 probably marked out as a chain of elevations, from the waste 

 of which the boulders and pebbles of the haimanta conglomerate 

 and of the Simla rocks were derived. The latter supposition is 

 also advanced by the authors of the " Manual." ^ 



The palaeozoic group forms an uninterrupted sequence from 

 the lowest haimantas to the upper carboniferous ; and this 

 sequence is the same, or nearly so, in all the sections of the 

 Central Himalayas. The first indications of a disturbance are 

 noticeable in the upper carbonifeious. Certain beds of the latter 

 are wanting in some sections, and I found the next following 

 system overlapping what I must look upon as an eroded surface 

 of upper carboniferous. 



Nearly everywhere I found the latter overlaid by a great 

 sequence of beds, which represent permian, trias, rhsetic, and 

 lias. This group of system- forms an uninterrupted sequence, 

 with conformable bedding throughout. The base of the sequence 

 is everywhere seen to be dark crumbling shales, which contain 

 a palaeozoic fauna, probably permian in character, which gradu- 

 ally passes into lowest trias beds through dark limestones and 

 shales which have yielded a curious fauna, some of the pecies of 

 which have strong affinities with permian forms. On it rest 

 ' Page 679. 



NO. II 6 I, VOL. 45] 



lower trias beds, followed by a continuous succession of strata, 

 which reach up into the lower lias. 



The same condition prevails in Spiti, where the lower lias is 

 also well represented. 



The lias limestones and shales are overlaid l;y Jurassic (Spiti) 

 beds, which have yielded a large number of fossils, but which 

 have not yet been entirely examined. Most of them appear 

 to belong to the upper jurassics rather than middle or lower. 

 Whether the latter is represented or not, is not quite clear, but 

 the bedding of the Spiti shales is isoclinal with the lower lias, 

 and if there is an unconformity between these systems, it may 

 only be conjectured from the sudden and entire change in 

 lithological character of the two formations, coupled with the 

 absence of lower Jurassic forms amongst the species found in the 

 Spiti shales. 



From this formation there is a gradual passage into the greenish 

 shales and sandstones of the cretaceous (with perhaps upper 

 Jurassic), the Gieumal sandstone of Stoliczka. Again a sudden 

 change in lithological character from these sandstones into the 

 white limestone of the upper cretaceous seems to point to the 

 probability of there having occurred physical changes on a large 

 .scale after the deposition of the lower cretaceous. In the Central 

 Asian area, and also in the Perso-Afghan region, a strongly 

 marked overlap of the upper cretaceous over the neocomian 

 limestones may be observed. 



Probably similar features will be found to exi-st in the Himalayan 

 area, the cretaceous rocks of which have not been closely studied. 



The tertiary system is fully developed, though few fossils were 

 found in it. A great unconformity occurs between certain sand- 

 stones which cannot be older than upper eocene (overlying 

 nummiililics), and are probably of miocene age, and horizontal 

 beds of clay, sand, gravels, and sandstone, which form the high 

 table-land of Hundes, which, having yielded mammalian bone 

 remains, are commonly known as the ossiferous beds of Hundes. 



From the foregoing it will be seen that special disturbances 

 must have occurred in early geological times, and have been 

 repeated periodically. 



It is very certain that near the beginning of the haimanta era 

 sufficient physical changes have occurred not only to completely 

 alter the lithological character of the deposits in course of forma- 

 tion, but also the area in which the latter were laid down. The 

 great thicknesses of coarse conglomerates, which are of wide- 

 spread extent in the lower haimantas, indicate the nearness of 

 land at the time, or, as I may term it, the existence of an early 

 region of elevation in place of the present area of the ('entral 

 Himalayas. At the same time lithological, not less than 

 structural, conditions point to the probability of true haimanta 

 deposits having been laid down also on the south slope of what 

 is now the Central Himalayan region. 



The compression of the Himalayan, and indeed entire Central 

 Asian area, and consequent folding, and thus elevating of it, most 

 probably went on uninterruptedly and continuously from the 

 earliest epochs to the present; indeed, the natural forces exerted 

 on the surface of our globe condition this. But in addition to 

 this, periodical greater changes have taken place, and are proved 

 by the sections of the Central Himalayas. 



After the lower haimanta recession of deposits from the entire 

 Himalayan area into well-defined northern and southern regions 

 of formations, we find an undisturbed sequence of beds till the 

 upper carboniferous, when clear evidences of a great overlap may 

 be observed. This is well marked in, the Central Himalayas, 

 and is clearly proved in the Perso-Afghan area, where car- 

 boniferous marine limestones are followed by littoral deposits, 

 the upper beds of which contain a triassic fauna. Here we 

 have therefore a period of sub-aerial and marine erosion of the 

 carboniferous, followed by an overlap of probably a permian and 

 triassic sequence of deposits. 



The third period of disturbance seems to belong to the lower 

 Jurassic age, where a gap (partial or otherwise) between lower 

 lias and middle or upper jurassics is probable. 



I may mention that this gap is not observable in the Perso- 

 Afghan region, where the passage from the trias into jurassics 

 and neocomian is gradual. 



On the other hand, a decided overlap on an immense scale has 

 occurred in later cretaceous times in Central Asia, and we find 

 that hippuritic limestone covers both jurassics and neocomian 

 unconformably. Such is less apparent in the Central Himalayas, 

 though probable enough when considering the sudden change 

 from the sandstone and shales of the lower cretaceous to the 

 hard white and grey limestone of the upper cretaceous. 



The fifth period of disturbance, which is clearly shown in the 



