[248] An elevation of 20,000 and perhaps 22,000 feet might, I should think, easily be attained by practice, in Tibet, north of Sikkim.
I made frequent excursions to the great glacier of Kinchinjhow. Its valley is about four miles long, broad and flat: Chango-khang[[249]] rears its blue and white cliffs 4,500 feet above its west flank, and throws down avalanches of stones and snow into the valley. Hot springs[[250]] burst from the ground near some granite rocks on its floor, about 16,000 feet above the sea, and only a mile below the glacier, and the water collects in pools: its temperature is 110°, and in places 116°, or 4° hotter than that of the Yeumtong hot-springs, though 4000 feet higher, and of precisely the same character. A Barbarea and some other plants make the neighbourhood of the hot-springs a little oasis, and the large marmot is common, uttering its sharp, chirping squeak.
[249] The elevation of this mountain is about 20,560 feet, by the mean of several observations taken from surrounding localities.
[250] Supposing the mean temperature of the air at the elevation of the Momay springs to be 26° or 28°, which may be approximately assumed, and that, as some suppose, the heat of thermal springs is due to the internal temperature of the globe; then according to the law of increment of heat in descending (of 1° for fifty feet) we should find the temperature of 110° at a depth of 4,100 feet, or at 11,900 feet above the level of the sea. Direct experiment with internal heat has not, however, been carried beyond 2000 feet below the surface, and as the ratio of increment diminishes with the depth, that above assigned to the temperature of 110° is no doubt much too little. The Momay springs more probably owe their temperature to chemical decomposition of sulphurets of metals. I found pyrites in Tibet on the north flank of the mountain Kinchinjhow, in limestones associated with shales.
The terminal moraine is about 500 feet high, quite barren, and thrown obliquely across the valley, from north-east to south-west, completely hiding the glacier. From its top successive smaller parallel ridges (indicating the periodic retirements of the glacier) lead down to the ice, which must have sunk several hundred feet. This glacier descends from Kinchinjhow, the huge cliff of whose eastern extremity dips into it. The surface, less than half a mile wide, is exceedingly undulated, and covered with large pools of water, ninety feet deep, and beds of snow, and is deeply corroded; gigantic blocks are perched on pinnacles of ice on its surface, and the gravel cones[[251]] are often twenty feet high. The crevassing so conspicuous on the Swiss glaciers is not so regular on this, and the surface appears more like a troubled ocean; due, no doubt, to the copious rain and snow-falls throughout the summer, and the corroding power of wet fogs. The substance of the ice is ribboned, dirt-bands are seen from above to form long loops on some parts, and the lateral moraines, like the terminal, are high above the surface. These notes, made previous to reading Professor Forbes’s travels in the Alps, sufficiently show that perpetual snow, whether as ice or glacier, obeys the same laws in India as in Europe; and I have no remarks to offer on the structure of glaciers, that are not well illustrated and explained in the abovementioned admirable work.
[251] For a description of this curious phenomenon, which has been illustrated by Agassiz, see “Forbes’s Alps,” p. 26 and 347.
Its average slope for a mile above the terminal moraines was less than 5°, and the height of its surface above the sea 16,500 feet by boiling-point; the thickness of its ice probably 400 feet. Between the moraine and the west flank of the valley is a large lake, with terraced banks, whose bottom (covered with fine felspathic silt) is several hundred feet above that of the valley; it is half a mile long, and a quarter broad, and fed partly by glaciers of the second order on Chango-khang and Sebolah, and partly by filtration through the lateral moraine.
