lO 



NATURE 



[January 28, 1892 



Central Himalayas, occurred after the deposition of the sand- 

 stones which overlie the numviulitics of Hundes, and which are 

 probably of miocene age. A considerable gap seems to exist 

 between the latter and the ossiferous younger tertiaries which fill 

 the Hundes basin. 



There is clear evidence, therefore, of very early disturbances 

 having taken place in the Himalayan area. There are abundant 

 proofs that minor changes in the distribution of land and water 

 have occurred not only frequently, but we can scarcely believe 

 otherwise than that the forces which have resulted in the intricate 

 folding and crumpling of the great sequence of sedimentary and 

 crystalline strata must have been of very long duration, and were 

 probably existent from the very earliest date when the first grain 

 of sediment was deposited in the Himalayan seas. We can go 

 further. Whatever other — and as yet only dimly understood — 

 forces were at work to produce this contraction and folding of 

 the earth's crust, we know of two forces about which there can 

 scarcely be the slightest doubt. The first is the gradual cooling 

 of our earth, and consequent lessening and shrinking of the 

 surface of it. Secondly — and this is a force which may be 

 mathematically expressed — we know that the centrifugal force 

 endeavours to move every point on the surface of the earth in a 

 direction opposite to that in which gravitation attracts it. 



The actual force exerted is the resultant between the centri- 

 fugal and tangential forces, and it has the tendency, if I may so 

 express it, of gradually moving each point on the surface of the 

 earth towards the equator. It may be supposed that an enormous 

 sequence, of to a certain extent pliable deposits, trying to move 

 bodily, as it were, towards the equator, but en route arrested and 

 banked up against a rigid mass of which the peninsula of India 

 is a small remnant only, must necessarily have suffered v/rinkling, 

 and lateral crushing. 



These forces operated since the earth existed, and must be 

 active now. But throughout the great sequence of the palaeozoic, 

 mesozoic, and kainozoic deposits, we search in vain for an 

 internal explanation of the great unconformities and disturbances 

 of coast-line which have taken place at certain intervals, such as 

 I have sketched out above. That these changes were not local 

 overlaps only is apparent when we compare the Central 

 Himalayan area with the Perso- Afghan region. In the latter 

 the physical changes are far more clearly marked. At the close 

 of the carboniferous epoch, which was one of pelagic conditions 

 in the Hindu Kiish area, Khorassan and Persia, the distribution 

 of land and water must have considerably changed, as we find 

 immediately above the carboniferous limestone, shaly beds with 

 coal-seams, and conglomerates and partly littoral, partly fresh- 

 water conditions prevailed in that area till late into Jurassic 

 times. These disturbances, which are slightly indicated in the 

 Himalayas, are clearly shown and occur on a larger scale in the 

 West Central Asian area. 



The next great change in the Perso-Afghan area is the great 

 overlap of the upper cretaceous (hippuritic) limestone over the 

 neocomian, already alluded to. It has resulted in a great and 

 often strongly expressed unconformity. Again, another and 

 strongly marked change occurs in the middle tertiaries of the 

 Perso Afghan area. The purely marine miocene beds are over- 

 laid, often with isoclinal bedding, at other localities distinctly 

 unconformably, by upper tertiary freshwater deposits. If the 

 folding and crushing process were alone the cause of these — 

 shall I call them cycles of disturbances — then at least some 

 evidence of it should be observable within the sequences of 

 rocks as we see them. 



On the other hand, there is no direct evidence to show that 

 the raising of the Himalayas as a mountain system was in any 

 way due to these periodical fluctuations of sea-level, or, as Suess 

 terms it, the "positive " and "negative " movements of the liquid 

 covering of the earth. The evidence of the transverse valleys 

 in the Himalayas points even to the probability that the raising I 

 up of the chains of hills forming them, i.e. the folding and 

 crumpling of its rock strata, must have kept pace, step by step, 

 with the erosion by rivers which we now find traversing the 

 whole width of this mountain system. 



Such transverse valleys, however, can only date since the last 

 of the periodical changes spoken of, i.e. since the middle 

 tertiary epoch. Before that time, up to the point when the last 

 marine tertiary deposits were laid down along the margin of 

 the Himalayas, the relative position of Peninsular India and 

 Central Asia must have been the reverse of what we know them 

 to be now ; that is to say, the surface of the Central Asian 

 elevated massif must have been nearer the centre of our earth 



than the surface of the continent, of which the Peninsula cof 

 India forms only a portion of the remains. 



It is improbable that the folding action alone has been the 

 cause of the present structure and orographical features of 

 Central Asia and the areas south of it : for the final great 

 changes which have resulted in the draining of Central Asia of 

 the tertiary seas, of which nothing now remains but isolated salt- 

 water lake-basins, such as the Aral and the Caspian are, we must 

 look for other causes. 



Possibly such may be found in the sinking in of large portions 

 of the southern hemisphere which caused the submergence of 

 the Indo- African area below what is now the Indian Ocean. 

 With it the part now known to us as the Peninsula of India 

 may have partially broken down, though of that we have no 

 direct evidence, unless the improbability that the Central Asian 

 area could have been pushed up to its present elevation above the 

 Peninsula entirely through being folded might be adduced as 

 proof. Large tracts of Central Asia we know could never have 

 suffered folding to any but very slight extent, as, for instance, 

 the greater part of the tertiaries of the Turkistan region which 

 are often in undisturbed horizontal position. On the other hand, 

 these latter are but little raised above — some are even depressed 

 below — the level of India. 



In all these considerations and speculations two points seem 

 probable almost beyond doubt, namely : First, that the last and 

 main disturbance of physical conditions of the Central Asian area 

 has taken place in post eocene, perhaps in middle tertiary times, 

 and is most likely still continued to the present day.^ Secondly, 

 that this period of disturbance coincides with the sinking in of 

 the Indo-African continent, which "breaking down "caused the 

 final draining of the tertiary seas from the Central Asian area. 



Not so certain is whether the raising en bloc of the Central 

 Asian mass above the level of the Indian Peninsula is due only 

 to the folding process, or whether some movement downwards 

 of the Peninsula, in connection with the sinking in of the Indo- 

 African region, may not have had a share in producing the present 

 configuration of the Hundes plateau. Some such movement may 

 be conjectured. Certain supposed elevations of the Peninsula 

 may possibly be owing to "negative " movements of the area of 

 the Indian Ocean — in other words, to the sinking in of the ocean 

 bed.- 



NO. T161, VOL. 45] 



SCIENTIFIC SERIALS. 



American Journal of Science, January. — Theory of an inter- 

 glacial submergence in England, by G. Frederick Wright. The 

 theory of deep interglacial submergence which has been pro- 

 pounded to account for the shell-beds at Moel Tryfaen, near 

 Snowdon, and at Macclesfield, is opposed by several formida'ile 

 objections, viz. (i) the subsidence must have been one which 

 affected North Wales and central England without affecting the 

 region south of the the Thames and Bristol Channel ; (2) there 

 is in other places a considerable absence of marks of subsidence 

 over the northern part of the centre of England, where it is sup- 

 posed to have been the greatest ; (3) the Pennine Chain is not 

 more than 25 or 30 miles wide from east to west, yet east of 

 Macclesfield there is an entire absence upon its flanks both of 

 glacial deposits and of beach lines ; (4) the shell beds are strictly 

 confined not only to the area which was demonstrably covered 

 by glacial ice, but to those more limited areas which were 

 reached by ice that is known to have moved in its way over 

 shallow sea-bottoms; (5) the assemblage of shells is not such as 

 could have occurred in one place in the ordinary course of 

 nature. The author develops a system of glaciers which will 

 explain the facts at present known, upon the supposition of a 

 single glacial epoch. — The Permian of Texas, by Ralph S. 

 Tarr. It is shown that the Permian of Texas is, like other areas 

 of Permian, a deposit in large measure made in an inland sea. — 

 The chemical composition of iolite, by O. C. Farrington. The 

 formula obtained from two analyses of exceptionally pure speci- 

 mens of the mineral is H2O 4(MgFe)0 4Al203ioSi02, the 

 ratio of MgO to FeO in the two cases being as 7 : 2. — On a series 

 of caesium trihalides, by H. L. Wells ; including their crystal 

 lography, by S. L. Penfield. Upon adding bromine to a con- 

 centrated solution of Caesium chloride, a bright yellow precipi- 

 tate was obtained, from which crystals were formed having 

 the composition Cs.Cl.Brg. An attempt has been made to 



" Manual," pp. Ivi., ( 

 See " Manual," p. 68: 



0, &c. 



