556 



NATURE 



[Oct. 4) 1883 



maximum level of the Garo Hills, about 4000 feet, it would not be 

 a greater alteration of level than we can see now a very few miles 

 distant to the east. The base of the cretaceous formation re.sts on 

 granite at the peak of Kailas, about 3000 feet above the sea ; at 

 thirty miles eastward it is at the level of the plains of Sylhet, 

 scarcely removed above that level ; it is here we find a remarkable 

 depression right across the Assam range from north to south, 

 which it is curious to note faces immediately the Monas- valley 

 of the Bhutan Himalaya. 



Great lateral rolls or waves of the stratified rocks occur at in- 

 tervals all along the southern line of the chain, and apparently 

 have a connection with the transverse drainage line. This feature 

 is best seen if we follow the old miocene along its junction with 

 the older rocks. The miocene attains its greatest elevation at 

 Bisari and Keeran Peaks — 11,200 feet— close to the end of the 

 Pir Tanjal axis ; it falls thence towards Mari to 7000 feet, and 

 much lower towards the Potwar. Eastwards it is reduced, above 

 Poonch, to 9900 feet ; near Rajaurie to 7000 feet, and Kamrot 

 6700 feet — or a fall of 4500 feet in fifty miles. The elevation 

 increases again, upon the Chenab, to Scoo and 9500 feet; and, 

 facing the Chatadhar ridge, it is again of great elevation — 9096 

 feet at Hato Peak, and Mandhar 8932 feet. At the Ravi, by 

 Basaoli, there is a depression, east of that river to 4600 feet, 

 but it gradually rises again to 6100 feet at Dhurucnsala, under 

 the Dhaoladhar ridge, and retain; that altitude to the Beas and 

 Sutlej, where it falls again to 4000 feet, which is its altitude 

 about Nahun and the Jumna. In the Deyra Dhun it is only 

 3000 feet, but east of the Ganges, where there is a local bend in 

 the strike, it rises again considerably. Beyond this the country 

 has not been visited by me. In the eastern area, under Darjiling, 

 it is of little elevation, but rises to about 4000 feet, disappearing 

 altogether near Dalingkote, but near Buxa the formation reap*- 

 pears, and is only some 2000 feet. Nothing is known of the 

 older tertiary rocks up to the Aka and Dapha Hills, but here 

 they attain again large proportion — 4700 feet west of the Ranga 

 to 6000 feet beyond that river. South of the Assam range, 

 miocene strata, a disiinct group, attain 1500 f et, but are poorly 

 represented in places. At other points, as near the Sylhet bhils, 

 they are absent. Near Jaintiapur they expand and reach an 

 altitude of 3000 feet. South of the Lukah River the whole mass 

 gradually rises to 5000 feet near Asalu, and to 9S90 at Tapvo 

 Peak, its culminating point in the Naga Hills ; but these forma- 

 tions are, I believe, marine and estuarine. The great elevation 

 of tertiary rocks here is the exact counterpart of what has 

 taken place on the west, and both are on the great changes of 

 strike in all the formations. 



Within the mountains in the old rock basins— and these are 

 analogous to the valleys of the Alps— are pliocene and post- 

 pliocene beds of great thickness, but of fresh-water origin ; the 

 remnants of which are to be seen in Kashmir and Scardo at 

 intervals, along the valley of the Indus, and that large — now 

 elevated— accumulation at the head of the Sutlej River in Hundes, 

 first brought to notice by the labours of Captain (now General) 

 R. Strachey. The remnants of these deposits in Kashmir and 

 Scardo are found preserved in the more sheltered portions of the 

 valley basins, untouched by the denuding action during the 

 glacial period — the exponents presented to us of the enormous 

 denudation that went on during the post pliocene times, of 

 which the glacial period formed a part. The extent and dis- 

 placement of the upper pliocene beds is in North Italy and here 

 very similar. Often abutting horizontally against the mountains, 

 they are in other places found tilted at considerable angles on the 

 margin of their original extension. When we examine their 

 contents, we find that the fauna of that time in Asia, as well as 

 Europe, was more African in character, and genera now confined 

 to that continent were abundant far to the north. The sluggish 

 rivers and lakes of Sivalik times in Asia and of the correspond- 

 ing period in Europe were the home of the hippopotamus, 

 crocodiles, and tortoises, of which the common crocodile, the 

 gavial or long-snouted species, and an emys have survived the 

 many geological changes, and still inhabit the rivers and low 

 grounds of India to-day. The fresh-water shells are still the 

 same now as then. Many species of antelope lived in the neigh- 

 bouring plains and uplands; the elephant was there in the zenith 

 of its existence, for no less than thirteen species have reen found 

 fossil in Northern India ; but it is impossible, in a short address, 

 to enumerate the richness of this fauna, and the extreme interest 

 that surrounds it. 



Miocene of European Area.~Jl we now turn to Europe to 

 compare formations of similar age, Lombardy and the valley of 

 the Po, with the southern side of the Alps, present to us some- 



what similar physical features. A large area of about the size of 

 the north-west Punjab, once a part of the miocene sea, is occupied 

 by a remnant of rocks of that age, considerably elevated and 

 tilted, but not to such an extent as those of the Himalayas. 

 Near Turin these dip towards the mountains, and a very short 

 examination show s the undoubted glacial character of some of 

 the beds ; 1 and, as the whole formation is marine, their large 

 sharply angular material, much of which is Jurassic limestone, 

 was probably transported from the adjacent mountains by the 

 agency of ice in a narrow sea. 2 After the great crushing and 

 alteration of the previous outlines of the whole country another 

 sea filled the basin of the Po, and pliocene deposits were laid 

 down in a sinking area extending to the base of the mountains 

 all round the new bay or gulf. Re elevation again set in, and 

 with it, or soon after it, the advent of another, and the last, 

 glacial period. But the bounds of the pliocene sea extended 

 even farther than the base of the mountains. At the south end 

 of the Lago d'Orta, well within the hills, sheltering under the 

 isolated porphyry hill of Bucciofte, and 280 feet above the 

 present lake (or 1500 feet above the sea), I had the good fortune 

 to discover this summer a patch of pliocene sands and clays, 

 with marine shells in excellent preservation, which I am not 

 aware has been noticed before. Sixty-four feet of the section 

 is exposed, capped by moraine matter ; its base was not seen, 

 and the beds dip north This remnant tells us a good deal. 

 From where it rests there is a clear horizon to the north down 

 the lake to the junction of its river with the Toce — unmistakable 

 evidence that these beds must have extended far in this northern 

 direction, and that long fjord-like arms of the sea stretched up 

 as far as Domo d'Ossola on one side, and Bellinzona on the 

 other. This marine bed is far above the level of the Lago 

 Maggiore, but I may mention that I also found marine shells of 

 pleistocene age 112 feet above that lake near Arona, of which 

 details cannot here be given. 



Before the last great elevation of the Alpine chain the whole 

 line of sea-coast, therefore, ran even high up the long deep 

 valleys of Maggiore, Como, Garda, &c, during the early plio- 

 cene period ; the mountains, then quite as high as now, enjoying 

 a warm, moist climate, not a glacial one. Then came the 

 gradual but uneven elevation of the whole area, including the 

 miocene hills south of the Po, and lacustrine and estuary con- 

 ditions prevailed over much of the plain country. The lapse of 

 time was probably enormous, and as the land rose and the sea 

 retired the climate gradually became cooler, and ushered in the 

 glacial period. I d> not think it would be an exaggeration to 

 add another 5, coo feet to the Alpine peaks of that time, which 

 would give them an altitude equal to the Zaskar range of the 

 N.W. Himalaya of the present day. With the change and 

 the increased volume of the mountain torrents, the destruction 

 of the upraised marine pliocene beds commenced, and finally 

 culminated in the extreme extension of the glaciers even into the 

 plains ; they scoured out almost completely the whole of these 

 deposits, which then filled the great valleys and the country at 

 the base of the mountains, to redistribute them again over the 

 plain of the Po, and silt up what remained there of the old 

 estuaiy or gulf towards the east. The denudation of this 

 formation has been enormous along the base of the Alps, and 

 only mere remnants are to be found. It is easily seen that their 

 preservation is purely due to the accidental position in places 

 where the great denuding force — viz. the advance of ice from 

 the mountains — has been unable to touch them ; in other instances 

 the early deposition of moraine matter upon them has acted like 

 a shield, and. prevented their entire destruction. Such examples 

 are well seen near Ivrea, in the well-known section in the gorge 

 of the Chieusella near Stombinella, and in the moraine near 

 San Giovanni. 



The scattered remnants of the pliocene formation south of the 

 Alps, which took perhaps thousands of years to lay down, show 

 well how soon a great formation, together with the preserved 

 remains of the fauna living at the time, may be completely de- 

 stroyed by subsequent denuding forces. Similar destruction must 

 have occurred over and over again in past geological ages, and 

 shows clearly how the scanty, broken record can be accounted for. 



It is an established fact that the great valleys of the Alps and 



1 Refer to Gastaldi. 



2 No trace has been observed of this glacial period in the miocene of 

 India ; the most lofty portions of the chain had not then attained a greater 

 elevation probably than 14,000 to 18,000 feet, and the outer axis lines far 

 less However, in the tertiary beds (middle eocene?) of the Indus Valley 

 below Leh such conditions are indicated by Lydekker. Memoirs of 

 Geological Survey of India, vol. xxii. p. 104, which I have received since 

 this address was sent to press. 



