4«o 



NATURE 



[November 24, 192 1 



them Everest is the culminating point, 

 29,202 ft. above sea-level. The great geodesist, 

 George Everest, introduced compensation bars 

 in the measurement of base lines, and measured 

 many with marvellous exactitude ; he perfected 

 instruments and produced a theodolite with a 

 circle* of 36 in. diameter; he invented also the 

 heliotrope to supersede the pole when observing 

 angles. The Survey of India owes everything to 

 his creative genius, and Mount Everest is the 

 finest monument to his memory. More than this, 

 the survey now in progress in Thibet under Col. 

 D. Ryder, R.E., the present Surveyor General of 

 India, is extending the triangulation to the north, 

 so that of the great arc may follow and be con- 

 tinued many miles further. Pendulum observa- 

 tions will also be feasible, and all will combine 

 to give us a greater knowledge of the figure of the 

 earth's crust and of those irregularities which 

 cause the deviation of the plumb line from its 

 normal direction. 



Mount Everest, in common with all lofty points, 

 looks over many thousand square miles of the 

 earth's surface, which has seen enormous changes 

 with which the height of the mountain itself is 

 closely connected. For instance, the Garo Hills 

 are seen from it, 250 miles distant on the south- 

 east. Thev mark the western extremity of the 

 Assam Range, one which is geologically recent 

 and of elevation corresponding with that of the 

 Sivaliks in Nepal which Everest overlooks. The 

 view will embrace the great deltas of the Ganges 

 and Brahmaputra ; the courses of the main rivers 

 will be followed by their wide, sandy beds as they 

 issue from the mountains and flow to the sea, dis- 

 played as on a map— and what a changing map 

 it has been— how affected by seismic action — a 

 map of absorbing interest. Mount Everest is 

 close upon the southern face or scarp of what 

 may be termed an ancient plateau of denudation, 

 well shown in Photograph 5 reproduced in 

 the Geographical Journal for October, which 

 depicts what we see at the present day, 

 a surface configuration after thousands of 

 years of wear and tear. The high plateau 

 type of country of great elevation, none 

 of" it below 14,000 ft., can be said to commence 

 in Rupshu, is continued on the Pangkong Lake, 

 and widens out rapidly in Rudok. It is fairly 

 well populated by a 'hardy race having many 

 good qualities ; crops are raised with difficulty, 

 but enormous flocks and herds are reared. De- 

 nudation began with the very earliest Sivalik 

 deposits, and continued until a quite recent Glacial 

 period, one of extreme conditions. Even here, in 

 latitude 28°, the glaciers were of great extent, 

 though nothing compared with the lengths they 

 attained in the north-west Himalaya when the 

 Indus valley at Skardo was filled with ice and 

 moraines, and even in the valley of Kashmir, 

 latitude 34°, the Sind valley glacier extended to 

 the valley itself not far from Srinagar, and was 

 some forty miles long. Although hundreds of 

 travellers pass up and down this beautiful valley, 

 how very few of them know of this, yet the 

 NO. 2717, VOL. 108] 



rocks, ground by the ice and striated by the stones 

 which were embedded in it, are clearly to be 

 seen. 



During the Glacial period a great ice cap 

 covered all the country here ; and the work it per- 

 formed is shown in the rounded outline of the 

 spurs given off from Mount Everest. 



In the letter of October 2 from Kharta, 

 published in the Times of October 21, we have 

 the first record of the geological structure of the 

 Everest mass. It is short but worthy of notice. 

 Col. Howard Bury says : " Immediately to our 

 left towered up Makalu's great cliffs of white 

 granite, so steep as to be snow free ; it is a most 

 imposing and marvellous mountain, looking in- 

 credibly thin, so perpendicular are its sides." Is 

 this granite intrusive? Judging by analogy, it is. 

 What Everest is composed of we have yet to 

 learn. We have some data to guide us in Sir 

 Joseph Hooker's diary of the Tambar valley at its 

 southern end, where, on the Pemmi River, at 

 about 2260 ft., he recorded ("Himalayan 

 Journals," vol. i, p. 192, 1854): "The rocks 

 above 5000 feet were gneiss ; below this cliffs of 

 very micaceous schists were met with, having a 

 north-west strike and being often vertical; the 

 boulders again were always of gneiss." This 

 strike (the prevailing one in this area) would ex- 

 tend towards Everest, and indicates what may be 

 expected there. 



The valley of Nepal came into existence with 

 the great movements in late Tertiary times, when 

 the Sivaliks were compressed and elevated on a 

 belt of 1500 miles. A roll in the strata formed 

 the Dun through which the waters of the Kosi ; 

 and Gandak, keeping pace with the elevation, 

 slowly cut their exit to flow into the ancient de- 

 pression of the Bay of Bengal. The Nepal valley 

 is therefore, in its physical features, similar to 

 that of Assam on a very much smaller scale ; that 

 of the Deyra Dun is on a still smaller one. Look- 

 ing to the Sikkim side, situated only fifteen miles 

 from the plains, and towering above them, is the 

 conspicuous point Gyepmochi^ 14,418 ft. high. I 

 know it well ; it is of intrusive granite. It is con- 

 nected with Kangchenjunga by the high, parting 

 range, crossed at the Jalap La. Chamalarhi, 

 23,930 ft., which is seen from this direction on 

 the north, has been said to be of an intrusive rock. 



Going back to the Glacial period, it is worthy of 

 notice, as not generally known, that from Gyep- | 

 mochi deposits of morainic type extend to the 

 plain of the Bhutan Dooars. A stream of large j 

 blocks of granite (one 10 ft. long) can be followed i 

 for eight miles, and is a conspicuous feature. A 

 similar extension of ice action may be looked for ' 

 south of Mount Everest, but not at so low a level, 

 in the Nepal valley. 



The next main valley beyond Gyepmochi. 

 having its sources in Thibet, is the Am-mochu. 

 The scarp lies south of Cliumbi, as is shown in 

 the steep fall in the bed of the river to Tsangbe. 

 As it nears the plains it flows directly on to them ; 

 there is no Dun, but a massive limestone of un- 

 known age brought up by a great fault occurs at 



