Part 13 (1/2)
The valley of the Shayuk is widest at the point of its junction with the Nubra river. At this place the level plain, including the gently sloping alluvium on each side, has a breadth of about six miles. The width of the valley gradually diminishes as we recede from the centre, the mountains encroaching more and more, till at last they hem in the river, leaving no s.p.a.ce for villages or cultivation, and the valley ceases to be inhabited. The centre of the plain is uniformly occupied by a flat gravelly expanse, one to three miles in width, scarcely raised above the surface of the river, which, when flooded, covers a great part of it. On both sides of this gravelly bed, low platforms of alluvium, in the form of triangles, with their apices resting on the mountain ravines, slope very gently towards the base of mountains, which rise abruptly and precipitously on both sides of the valley, to a height of three or four thousand feet. Some of the more projecting spurs, even where the width of the valley is greatest, advance so far into the open plain as to abut upon the river and compel the traveller to ascend their slopes, in order to cross them in travelling from village to village.
The gravelly plain over which the Shayuk flows, is usually quite devoid of vegetation. A few scattered bushes of _Tamarix_ and _Myricaria_ appear, indeed, near its junction with the Nubra river, but further up the gravel is absolutely bare: in this it contrasts strongly with similar portions in the valley of the Nubra river, which are densely wooded. The cause of this difference seems to lie in the frequent floods which have, at different periods, devastated the whole course of the Shayuk valley, from the glaciers of Sa.s.sar. These floods, which appear to be due to the blocking-up of the upper course of the river by the ice, have been most destructive to the prosperity of the valley.
[Sidenote: VILLAGES.
_October, 1847._]
Throughout Nubra, the villages, with scarcely an exception, occupy the surface of the low platforms of alluvium which fill up the funnel-shaped terminations of the ravines. In Tibet the size of the villages, and the extent of cultivation by which they are surrounded, entirely depend on the supply of water and on the facility with which it can be diverted from its bed for purposes of irrigation; and as, in this district, the width and horizontality of the alluvial tracts are very favourable to the industry of man, the villages are in general large and surrounded with much cultivation. Indeed, a super-abundance of water is in general indicated by the swampy banks of the irrigation ca.n.a.ls, as the water, oozing through the loose gravel of the platforms, produces a dense jungle of _Hippophae_ scrub, which makes the cultivated tracts conspicuous, even in winter, when the trees are bare of leaves and the fields of crops.
This copious supply of water no doubt depends on the great elevation of the surrounding mountains, which everywhere rise, if not above, yet almost to the level of perpetual snow, which is about 18,000 feet, so that at the head of each little stream there is either a glacier, or a snow-bed which does not entirely melt till the latter end of autumn, affording therefore a nearly perennial supply of water. Even in the hottest months slight falls of snow are of occasional occurrence at all elevations above 16,000 feet; and as every range rises much above that height, a small addition to the supply is thus obtained.
The villages have generally a few fruit-trees, as well as a good many poplars and willows, which yield almost the only timber the inhabitants can command. The walnut and _Elaeagnus_, both of which trees find their upper limit in Nubra, are so extremely scarce that they are not available for such purposes.
In most parts of Nubra the soil is very generally saline, the dry gra.s.sy plains which are common on the banks of the streams being generally covered with a copious efflorescence of carbonate of soda; while the abundance of _Salsolae_ and other Chenopodiaceous plants on the dry alluvial plains, and even on the rocky hills, seems to prove that the saline matter is not confined to the immediate vicinity of water, or to the lowest levels, but is very generally diffused over the surface.
[Sidenote: VALLEY OF NUBRA RIVER.
_October, 1847._]
The valley of the Nubra river, for upwards of twenty miles, is very similar in general character to that of the Shayuk. The same wide gravelly expanse occupies its centre, forming a plain of one or two miles in width, through which the river runs in many branches. A great part of this gravelly plain, particularly on the right side of the valley, is covered by a dense thicket of _Hippophae_, extending continuously for four or five miles, usually impervious, except in certain beaten tracts, and tenanted by vast numbers of hares. The gravel on which this jungle grows is almost on a level with the river, so that it is very generally swampy, and traversed here and there by little streamlets of water. The _Hippophae_ is here a small tree, attaining a height of fifteen feet, with a short thick trunk and stiff crooked spinous branches.
[Sidenote: CHIRASA.
_October, 1847._]
In several parts of the course of the Nubra river, low hills rise in the valley, isolated, or nearly so, from the mountain ranges behind, and forming, therefore, a remarkable feature. On one of these, on the right bank of the river, is situated the little fort and village of Chirasa, a considerable ma.s.s of houses, of a cla.s.s a little better than those usual in the district, and conspicuous from their elevated position. The rock on which they stand is composed of a hard porphyry, which has been injected from below, and has displaced the black slate, which is the more usual rock in the lower part of this valley.
In the lower part of the ravine behind the town of Chirasa, the alluvium is more extensively developed than usual in this valley, where aqueous action seems in a great measure to have removed the acc.u.mulation of detritus, which once, no doubt, occupied the whole valley. Beds of gravelly conglomerate, at times pa.s.sing into fine clay, may here be seen, at a height of perhaps 1000 feet, on the mountain-sides in isolated patches, generally faced by cliffs, in which a tendency to horizontal stratification is observable.
[Sidenote: NUBRA VALLEY.
_October, 1847._]
The lower part of the Nubra valley is very fertile, and on the east side cultivation extends, with little interruption, from Tirit as far as Panamik, in a belt varying in width from a few hundred feet to nearly a mile. The villages are large, and seem populous. Many of the houses are very substantially built, and the long sacred walls, called Mane, are numerous, and of great length and size. Several watercourses, which are carried along the sides of the hills at an elevation of several hundred feet above the cultivation, and are easily recognizable by the fringe of _Hippophae_ bushes, which forms an impenetrable belt along their margins, indicate a degree of industry and energy very unusual in Tibet, where, however, the amount of cultivable land is seldom sufficient to promise much reward to any extensive and elaborate system of irrigation.
As the advanced period of the year rendered exploration at great elevations scarcely practicable, and made it desirable to reach a lower level as soon as possible, I did not remain more than a week in Nubra. On the 22nd of October I started from Lyakjung, at the mouth of the Nubra river, towards Iskardo, following the course of the Shayuk river. The district of Nubra extends about thirty miles below the junction of the river of that name with the Shayuk; but I found the level valley gradually to diminish in width as I descended. On the 22nd of October I encamped at Hundar; on the 23rd, at Tertse; and on the 24th at Unmaru, beyond which village there is no cultivation, and the valley becomes extremely narrow. On the 25th of October I reached an encamping ground called Kuru, at the termination of the Nubra district, where the mountains, which for three days had gradually been encroaching on the valley, completely closed in, and the river entered a deep gorge, walled in on both sides by lofty and almost perpendicular cliffs of black slate.
[Sidenote: LOWER NUBRA.
_October, 1847._]
[Sidenote: FOSSIL Sh.e.l.lS IN THE CLAY.
_October, 1847._]
The general aspect of the lower part of Nubra requires no particular description, as it presents much the same features as the other parts of the district. The mountains on both sides of the valley are not less steep, barren, and inaccessible than elsewhere in Tibet. The alluvial platforms, which were everywhere present, increased remarkably in thickness as they diminished in size. Widely spread out in the broadest parts of the valley, they were not more than from twenty to forty feet thick where cut across by the river, and sloped very gently. In the narrower parts of the valley they were often not less than a hundred feet high along the river. In structure these platforms varied much. The greater part certainly consisted of gravel and clay, quite unstratified, but the lower beds were very frequently fine clay, or fine sand, or alternations of these two. The superposition of the coa.r.s.e beds to the fine was nearly uniformly observed, though occasionally, above the fine clays, alternations of gravel with thin beds of sand or clay were met with. In one place, on the north side of the river, nearly opposite to the village of Tertse, I found these beds to contain fresh-water sh.e.l.ls. The fossiliferous bed was elevated very little above the present level of the river, and was composed of a fine somewhat sandy clay, stratified horizontally, and covered with upwards of fifty feet of coa.r.s.e conglomerate. The sh.e.l.ls, which were all small, were species of _Planorbis_ and _Lymnaea_, apparently identical with those afterwards found in the neighbourhood of Iskardo, but quite different from those of the salt lake of Thogji.
The villages of Lower Nubra are not numerous, but some of them possess very extensive cultivation. Hundar in particular, at the mouth of a large ravine, by which a considerable tributary stream descends from the south (at the source of which there is a pa.s.s across the range into the valley of the Indus), is a very large village (probably the most populous in Nubra), with very fine orchards of apricot-trees.
Walnut, mulberry, and _Elaeagnus_ became common at Unmaru, on the north bank of the river. Perhaps the gradual narrowing of the valley may have a considerable effect in modifying the climate, for the diminution of elevation is very inconsiderable, the river at Kuru being nearly 10,300 feet above the sea, or not more than 300 feet lower than the junction of the Shayuk and Nubra rivers.
In this part of its course, and at this advanced season, when the great summer floods are over, the Shayuk appears to be everywhere fordable. It is, however, a n.o.ble stream, with a rapid current; and is usually divided into many channels. Above Hundar, where I forded it, one branch was not less than 300 feet wide, and was from one to two feet deep. Opposite Tertse, again, I found the stream running in seven branches, of which three were from 100 to 150 feet wide, and had an average depth of about two feet, increased in the centre to about three. The other branches were, however, much smaller.
[Sidenote: GREAT FLOOD OF THE SHAYUK.
_October, 1847._]
In several places between Hundar and Tertse, on the gravelly plain which skirted the river, I observed manifest traces of a flood, consisting of such rejectamenta as are usually seen deposited by swollen streams, fragments of wood and twigs, straw, sheep's dung, and other light materials, forming a bed two or three feet wide, continuous in many places for hundreds of yards, at a distance of not less than half a mile from the river. To my inquiries as to the nature of the flood which had deposited these reliquiae, the invariable reply was, that a great flood had taken place five years before, by the bursting of a lake called Khundan Chu, at which time the whole course of the river was devastated, and much destruction of property, sometimes even life, ensued, particularly in the narrower parts of the valley. In most parts of the world the preservation of such insignificant vestiges of a flood for so long a period would have been impossible; but here, where rain is almost unknown, and where the winter falls of snow seldom exceed one or two inches, there are no disturbing causes which could prevent them from remaining till carried away or altered in position by another similar flood. I should, therefore, have had no difficulty in attaching credence to the testimony of the inhabitants of the country, even had I not, in my journey down the river, received the most abundant proofs that the flood was everywhere well known, at least as far as Iskardo.
The vegetation of Lower Nubra had so entirely disappeared, that I could form scarcely any idea of its character; but, as the general aspect of the country was unaltered, I had no reason to look for any change. In the gravelly bed of the river, bushes of _Myricaria_ and _Tamarix_ were common; thickets of _Hippophae_, loaded with very acid yellow berries, lined the watercourses, forming an impenetrable barrier. Little bushes of _Artemisia_, _Lycium_, _Perowskia_, and _Ephedra_, were also occasionally seen on the rocks, but the herbaceous vegetation had quite withered away. In the villages, the cultivated trees were also rapidly shedding their leaves; constant night frosts, and frequent falls of snow on the mountain-sides, having so far reduced the temperature that winter was evidently at hand.