Western Himalaya and Tibet / A Narrative of a Journey Through the Mountains of Northern India During the Years 1847-8

by Thomas Thomson

BORAX LAKES OF TIBET.
September, 1847.

It has long been known that borax is produced naturally in different parts of Tibet, and the salt imported thence into India was at one time the principal source of supply of the European market. I am not aware that any of the places in which the borax is met with had previously been visited by any European traveller, but the nature of the localities in which it occurs has been the subject of frequent inquiry, and several more or less detailed accounts have been made public. These differ considerably from one another, and no description that I have met with accords with that of the Pugha valley. Mr. Saunders[13] describes (from hearsay) the borax lake north of Jigatzi as twenty miles in circumference, and says that the borax is dug from its margins, the deeper and more central parts producing common salt. From the account of Mr. Blane[14], who describes, from the information of the natives, the borax district north of Lucknow, and, therefore, in the more western part of the course of the Sanpu, it would appear that the lake there contains boracic acid, and that the borax is artificially prepared by saturating the sesquicarbonate of soda, which is so universally produced on the surface of Tibet, with the acid. At least, the statement that the production of borax is dependent on the amount of soda, leads to this conclusion. The whole description, however, (as is, indeed, to be expected in a native account of a chemical process,) is very obscure, and not to be depended upon. Mr. Saunders does not notice any hot springs in the neighbourhood of the borax; but in the more western district described by Mr. Blane, hot springs seem to accompany the borax lake as at Pugha.

It is not impossible that the three districts in which the occurrence of borax has been noticed, which are only a very small portion of those which exist, may represent three stages of one and the same phenomenon. The boracic acid lake may, by the gradual influx of soda, be gradually converted into borax, which, from its great insolubility, will be deposited as it is formed. On the drainage or drying-up of such a lake, a borax plain, similar to that of Pugha, would be left behind[15].

From Pugha, two roads towards Le were open to us. We might either return to the Indus, and follow the valley of that river throughout, or proceed by a more direct route across the mountains to join the road from Lake Chumoreri to Le, by which Mr. Trebeck had travelled on his way to Piti. As we knew that the Indus route would be surveyed by Captain Strachey, who was desirous of following the course of the river as far as practicable, we preferred the more mountainous road, and, therefore, on leaving our encampment at Pugha, on the morning of the 23rd of September, we continued to ascend the valley of the little stream, on the banks of which we had been encamped. For the first two miles the plain was nearly level, and similar in character to what has just been described, hot springs being observed at intervals.

SULPHUR MINE.
September, 1847.

Two miles from our encampment, we stopped and examined the spot whence sulphur is obtained, at the base of the mountain slope on the north side of the valley. Ascending a few feet over a loose talus of shingle, which skirted the bottom of the hill, we found two narrow caverns in the slaty rock, apparently natural, or only a little widened by art, roughly circular, and less than three feet in diameter at the mouth. One of these caverns continued a long way inwards, nearly horizontally, but it contracted considerably in diameter, and was so dark that we could not penetrate far. The rock was principally gypsum, interstratified with very friable mica-slate. Sometimes the gypsum was amorphous and powdery, at other times in needles two or three inches long, perpendicular to the strata of slate. The sulphur was in small quantities, scattered among the gypsum, and was more abundant in the lower beds. It was frequently in very perfect crystals, not, however, of any great size.

The air which issued from these funnel-shaped apertures was very sensibly warm, and had a strongly sulphurous odour. Unfortunately, we had not anticipated the necessity for observing the temperature, which was not by any means oppressive, and was only remarkable in contrast with the extreme cold of the external air.

In the neighbourhood of the sulphur-pits, the hot springs along the course of the stream were very numerous, evolving much gas. A little higher they ceased altogether, and the upper part of the plain was without any springs, as was evident from the quantity of ice by which it was covered. For more than a mile it was a dead level, and very swampy; but afterwards the valley became gently sloping and gravelly, the little stream being often hidden under the pebbles. Large boulders of the same granite which we had observed the day before, were scattered over the surface. The vegetation in this valley was extremely scanty, a few scattered tufts of Dama, and some shrubby Artemisiæ, were occasionally seen, but the herbaceous vegetation had been almost entirely destroyed by the intense morning frosts, which had for some time been of daily occurrence. On the latter part of the day's journey the rock on the mountain-side changed from mica-slate to gneiss, of which very lofty scarped cliffs rose abruptly on the right hand. We encamped on a level spot, after ten miles of almost imperceptible ascent.

Next morning we continued to ascend the valley, which was now very rugged, from masses of boulders, which were heaped one on another to a very great thickness. The stream had cut for itself a narrow channel, nearly a hundred feet in depth, the walls of which were entirely composed of huge incoherent masses of rock, all more or less angular. A walk of three miles brought us to the crest of the pass, which was nearly level and grassy for about a mile; its elevation was about 16,500 feet. The pass (Pulokanka La) is a very deep depression in the axis of the chain, which runs parallel to the left bank of the Indus, separating the waters tributary to that river from those which join the Zanskar river, some of the feeders of the latter springing from the valleys on the western slopes of these mountains. The hills right and left of the pass rise very boldly into rugged masses, contrasting strongly with the level plain which constitutes the pass, in which the watershed is scarcely perceptible.

SALT LAKE.
September, 1847.