594 



SCIENCE. 



[Vol. II., No. 39. 



He considered it to be made up of a series of parallel 

 ranges running in an oblique line to the general direc- 

 tion of the whole mass, the great peaivs being on ter- 

 minal butt-ends of the successive parallel ranges; the 

 watershed following the lowest parts of the ridges, 

 and the drainage crossing the highest, in deep gorges 

 directly transverse to the main lines of elevation. 



We can, in a measure, exemplify the structure of 

 the Himalaya by that of the bones of the right hand, 

 with fingers much elongated and stretched wide apart, 

 of which the wrist and back may represent the broader 

 belt of granitic rocks of the eastern area; the thumb 

 and fingers, the more or less continuous ridges of 

 the north-west, some less prolonged than othei s to the 

 north-west, such as the Chor axis, which may be rep- 

 resented by the thumb, terminating on the southern 

 margin near the Sutlej. The left hand placed oppo- 

 site will represent the same features to the west of 

 the Indus. We will even carry this simile farther, 

 and, as a rough illustration, suppose the intervals or 

 long basins between the fingers to be filled with sedi- 

 mentary deposits, and the fingers then to be brought 

 closer together, producing a crushing and crumpling 

 of the strata. At the same time, an elevation or 

 depression, first of one or more of the fingers, then of 

 another or of the whole hand, has taken place, and 

 you are presented with very much what has gone on, 

 upon a grand scale, over this vast area. As these 

 changes of level have not taken place along the 

 whole range from east to west in an equal extent, 

 but upon certain transverse or diagonal lines, undu- 

 lations more or less great have been the result; and 

 some formations have attained a higher position in 

 some places than in others, producing, very early in 

 the history of these mountains, a transverse system 

 of drainage-lines, leading through the long axial 

 ridges. 



The last efforts of these rising, sinking, and lateral 

 crushing, and, as I believe, very slowly acting forces, 

 are to be seen at the southern face of these moun- 

 tains, in the tertiary strata that make up the sub- 

 Himalayan axis (Sivalik), — a topographical feature 

 which is most striking by reason of its persistence 

 and uniformity for some 1,000 miles. From Assam 

 on the east, to the Puujab on the west, bending round 

 and extending to Scinde, this fringing line of parallel 

 ridges is found at the base of the Himalayas, some- 

 times higher, sometimes wider, often forming ellipti- 

 cal valleys. Only in one part of the belt, east of the 

 Teesta, are they absent altogether for a distance of 

 fifty miles. These formations are of vast thickness, 

 and, in the Punjab, cover an area of 13,000 square 

 miles. The whole of this material has been derived 

 from the adjacent Himalayas, and has travelled down 

 valleys that have been excavated in pre-tertiary times. 

 This points to a slow subsidence of the whole south- 

 ern side of the mountain mass, deposition generally 

 keeping pace with it, broken off by recurring long 

 intervals of re-elevation. 



The next most interesting feature connected with 

 the former distribution of land and sea is that these 

 sub-Himalayan formations are fresh-water, or tor- 

 rential, showing that since nummulitic or eocene 



times the sea has never washed the base of the Him- 

 alayas. In fact, there is no evidence of this from the 

 gorge where the Ganges leaves the mountains up to 

 the base of the Garo Hills. I believe that from As- 

 sam to Scinde there once existed a great river, receiv- 

 ing its tributaries from the Himalayas, partly a land 

 of lakes and marshes, the home of that wonderful 

 mammalian and reptilian fauna which Cautley and 

 Falconer were the first to bring to light. The south- 

 ern boundary of this long alluvial plain was formed 

 by the present peninsula of India, and probably of 

 the extensicm of the Garo and Khasi Hills westward 

 to the Eajmahal Hills. Depression has been consid- 

 erable in the neighborhood of Calcutta, nearly five 

 hundred feet. At three hundred and eighty feet, beds 

 of peat were passed through in boring; and the lowest 

 beds contained fresh-water'shells. The beds, also, 

 were of such a gravelly nature as to indicate the 

 neighborhood of hills, now buried beneath the Gan- 

 ges alluvium. This is precisely the appearance of the 

 country above Calcutta, on approaching the present 

 valley of the Brahmaputra. The western termination 

 of the Garo Hills sinks into these later alluvial depos- 

 its; and along'the southern face of the range, up to 

 Sylhet, the waters of the marshes during the rainy 

 season wash the nummulitic rocks like an inland sea, 

 and point to the very recent depression of all this area. 

 The isolated granite hilltops jutting up out of the 

 marshy country from Dhoobri to Gwalpara, and on to 

 Tezptir, all testify to the same continuous depression 

 here. It is exactly north of this that we find the Si- 

 valik formations, absent at the base of the Himalayas. 



This gradual depression of the delta of the Gan- 

 ges, the relative higher level of the water parting and 

 shifting of the Punjab rivers westward, appear to be 

 only the last phase of that post-pliocene disturbance 

 which broke up the Assam sub-Himalayan lacustrine 

 system draining into the Arabian Sea. Zoological 

 evidence, which I cannot here find space to quote, is 

 also in favor of this former connection of the now 

 separated waters of the Ganges and Indus basins, and 

 the hill-tracts of the Garo and Khasi Hills with penin- 

 sular India. 



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 thick- 

 ness, but of fresh-water origin; the remnants of 

 which are to be seen in Kashmir and Scardo at in- 

 tervals, along the valley of the Indus, and that large, 

 now elevated, accumulation at the head of the Sutlej 

 River in Hundes, — all in the more sheltered por- 

 tions of the valley basins, untouched by the denuding 

 action during the glacial period. The extent and 

 displacement of the upper pliocene beds in north 

 Italy and here are very similar. Often abutting hori- 

 zontally against the mountains, they are in other 

 places found tilted at considerable angles on the 

 margin of their original extension. Wlien we ex- 

 amine their contents, we find that the fauna of that 

 time, in Asia as well as Europe, was more African 

 in character, and included the hippopotamus, croc- 

 odiles, and tortoises; of which, the common croco- 

 dile, the gavial or long-snouted species, and an Emys, 



