THE SIACHEN AND TERONG

HENRY OSMASTON

THE EASTERN KARAKORAM range has many features of interest for a glaciologist and geomorphologist. The Siachen (Rose) glacier is one of the largest glacier in the world outside the Antarctic, 70 km long and several km wide. There are many other glaciers which range from narrow steep icefalls between precipitous wails and peaks of granite to broad snowfields with barely perceptible slopes. Many are striped with long and distinct medial moraines composed of different kinds of rocks, and with bands of huge ice-pyramids. Indeed the name Rimo for the group of peaks we were attempting is derived from the glaciers of the same name which flow easiwards from these peaks, and this in turn means 'striped' in Ladakhi. It is not derived from the Ladakhi word ri =. peak, unlike the names of several other mountains in Ladakh nor the Lharimo (= holy peak, female).

Having worked for a couple of summers in Zanskar, I was delighted to have this opportunity to explore northern Ladakh as well. The geology of these mountains is not well known. The route from Leh climbs first over the Khardung la, formed in the granites of the Ladakh range, and then drops down to the volcanics of the deeply-glaciated {Shyok and lower Nubra valleys. Further up, the Nubra valley passes obliquely into the massive granites which form the spectacular peaks and steep-sided gorges so typical of the Karakoram. There are also substantial bands of dark "shales, white dolomites and other sedimentary rocks, and one of these intersects the Terong valley system. These often form less precipitous, scree-covered slopes, and conspicuous dark or light moraines on the glaciers.

After various problems with red tape I eventually arrived at the Siachen glacier a fortnight after the others, an ugly wilderness of moraine-covered ice where I had to pick my way by torchlight between steep ridges and deep melt-hollows. Unfortunately I could not examine the terminus in daylight and record its exact position, but my impression is that it has not altered much since Visser's expedition mapped it in 1929 (Visser 1934) (Fig. 3). From that map Ruck (1934) inferred that the glacier had retreated by about 130 m since previous observations by him in 1909, but reported that in 1909 the glacier had advanced 750 m from a position previously mapped by Ryall (Survey of India) in 1862.

Plates 1-2-3

As dawn broke about two hours from the terminus I saw the first of the huge white ice-pyramids which are such spectacular features of many Karakoram glaciers. These stand up to 20 m high in serried ranks down the middle of the glacier, in striking contrast to the rock mantled surface either side of them. Workman (1914) writing at a time when the dynamics of glaciers were little understood, thought these features had been squeezed up by pressure from the ice either side of them, and indeed they give this impression, though I am sure this is incorrect. At this point I felt a profound relief that I was to work on the smaller Terong glacier and not on the Siachen glacier itself — it was altogether too big for a single worker to tackle, especially one who was twice the average age of the rest of the expedition members.

The ice of the Siachen glacier bulges sideways into the mouth of the Terong valley, (Plate 2) after which one traverses 6 km of ice-free valley before meeting the terminus of the Terong glacier. There is a similar situation where the South Terong glacier fails to join the North Terong glacier. At all these places too, the ice fronts seem to be in about the same position as when they were surveyed by Visser's party.

My two porters, kindly provided by the army, left me at the snout of the Terong glacier and I spent the next four days slowly pottering up the North Terong glacier in search of the others, studying the glacier on the way. Fig. 1 is a map of the North Terong glacier traced from a Landsat satellite image, with the different zones of the glacier marked, and an idealised sketch of a section across it. Here in Zone C there were again rows of big ice-pyramids, but there were also many ice-pinnacles up to 2 m high, some like columns with large rock tables still balanced on top, others more pointed where rocks appeared to have fallen off recently. Besides these, there were large areas covered with lower ice-pinnacles ranging from ten centimetres to a metre in height, rather similar to the snow 'penitents' described particularly on high snow-fields in the Andes.

The surface of this middle stretch of the glacier was also marked by several longitudinal ridges of moraine-covered ice up to 30 m high. Indeed the ABC was so well concealed behind one of these ridges that I walked right past it to the more open and level icefields beyond, at about 5500 m (Zone B); here there were still the remains of last winter's snow concealing the crevasses, but it is clear from satellite images that later in the season the whole of this expanse becomes bare ice. It is fed partly by small tributaries on the east which receive snow from the steep flanks of the great Rimo peaks, but also by falls from the ice-cliffs which bar its head. Stephen Venables' photos from high on Rimo I show that beyond these cliffs is an extensive ice-plateau ('Teram Shehr ice-plateau') at about 6000 m which contrasts surprisingly with the jagged peaks and steep relief around ABC and is a source of ice for the Teram Shehr glacier as well as the North Terong. (Plate 1) There is a similar high snow and ice-plateau to the east of the Rimo peaks which flows eastwards to feed the wide South Rimo glacier. It is these extensive high areas of permanent snow in Zone A which form the main accumulation areas of the largest Karakoram glaciers and account for their huge size. There is no information on the annual snowfall at these altitudes, but some measurements on the Batura glacier, further west, indicate that it is probably equivalent to more than 1000 mm of water (Shi Yafeng and others, 1979). This is about ten times the rainfall in the lower Nubra valley.

Eventually I found the ABC, perched on a subsidiary ridge of the glacier and endeavoured to make myself comfortable on a single layer of granite boulders over ice. I was very lucky in that the next fortnight gave us continuously good weather, several days being completely cloudless, and I spent it studying the effects of this intense radiation on the glacier surface.

Where the ice surface is clean and white most of the sun's rays are reflected, but sufficient are absorbed to result in a surface lowering of about 3-4 cm/day in Zone C. If the ice has silt or stones on the surface, these absorb more radiation from the sun, and convey this heat to the ice below them, making it melt faster. Thus scattered stones will sink into 'cryoconite' holes in the ice, but larger rocks may be so thick that this heat is not conducted through them. As the ice below is shaded from the sun it melts more slowly than usual, and the rock is left standing on a pedestal of ice. The minimum sized rock to permit this was about half a metre thick and rather larger in length and breadth. Our tents clearly met the same requirements, as after a few weeks they were left perched on pedestals of ice about 60 cm high.

Similarly if there is a thin continuous cover of grit and stones, the whole ice surface beneath it will melt faster than clean ice, but if the cover is thicker then it protects the ice beneath which is left upstanding. This is the origin of the big longitudinal ridges in Zone C of the glacier; some are clean white ice, others are thickly covered with moraine, while between them are valleys where the dirt covering is thin. At ABC, ice with up to 1 cm of grit on it melted twice as fast as clean ice, whereas with a cover of 5 cm of grit or stones it melted at only half the rate of clean ice.

Nearer the terminus (Zone D) the whole surface of the glacier is covered with a protective layer of moraine; melt hollows are initiated by crevassing, which exposes to the sun new surfaces so steep that only a sparse layer of dirt can cling to them, and these melt back leaving stone covered ridges between crater-like hollows. This blanket of moraine allows the glacier to extend much further than it would if the ice were bare: on the Batura glacier up to 18 m of ice a year were melted from bare ice surfaces near the terminus whereas under moraine cover this was reduced to 5 m.

It is not clear why the ridges of clean ice develop into rows of pyramids, but it appears to be associated with the patterns of crevassing and foliation in the ice. There are three reasons why the tops of pyramids and pinnacles probably melt more slowly than the ice at their base, resulting in apparent 'growth'; first, the tops are in a cooler environment; second, any dirt melts out of the tops and is shed on to the basal ice; third, the ice at the base mostly melts, while some of that at the top probably sublimes (turns directly into water vapour) which consumes much less ice for a given input of heat energy. (Plate 3)

The development of the many small waterfilled holes, up to 30 cm across and of similar depth, with vertical sides, is also interesting and was first described by Workman (1914). The sun's rays are so intense and the ice so transparent that even when a pebble (or a cluster of pebbles and grit) has melted a little way into the ice, sufficient radiation is still received by it through the ice to cause further melting down to 30 cm or more, so that the depth then remains constant despite continued lowering of the ice surface. Each night the water surface freezes on to the sides of the hole; each day this ice is melted by the sun on the sides facing south, east and west, but not on the north-facing side which is thus reinforced, and eventually is left projecting above the general ice-surface as a small blade-like pinnacle (Fig. 2). The nightly ice-levels show as ridges on the north facing wall and thus provide a simple measure of the rate of surface melting. The hole is usually elongated E-W because the morning and evening sun can shine more effectively on the west and east sides. The water-level is maintained about 20 cm below the ice surface, because the surface melting also develops a surface zone of porous ice of about this thickness. At ABC it froze every night, but by day the glacier surface was running with water. Slushy swamps on fairly level ice fed into long surface streams that eventually plunged into moulins; Dave broke his little finger jumping one of these channels. Sometimes they ran into temporary ponds on the glacier like the two near ABC which dropped suddenly by a metre or two during our stay due to some enlargement in the subglacial drainage channel. When the party first arrived the South Terong river had been dammed into a lake by the North Terong glacier; ten days later this had drained under the ice, leaving only some ice-floes stranded on the shore.

The strong, braided outwash streams rapidly spread out all the moraine that is deposited at the terminus of the glacier so I was unable to form any idea of whether the Terong or Siachen glaciers are currently advancing or retreating. There are some fairly young deposits of moraine clinging to the valley walls above glacier level, indicating a formerly greater ice thickness, but there is a notable lack of long lateral moraines providing easy access routes, which are common elsewhere in the Himalaya; probably this is due mainly to the confined, steep-sided valleys below the firnline which the glaciers fill from wall to wall. Up to the end of June these rivers can usually be forded with care, especially in the early morning when they are lowest. After 10 days of sunny weather in early July however, the Terong Topko rose to a raging torrent full of ice-floes, cutting our return route and nearly drowning our LO who bravely but rashly tried to ford it.

Previous glaciations

There is abundant evidence that the glaciers were formerly more extensive than now on several occasions. The main Indus valley itself was glaciated a hundred thousand or more years ago, but shortly after leaving Leh on the way to the Karakoram over the Khardung la the road climbs along a conspicuous moraine probably only about 15,000 years old. The first halt for tea at South Pulu is near some younger moraines, and a similar sequence in reverse can be seen in the valley on the far side of the pass at North Pulu and Khardung villages. As the road descends to the deep glaciated valleys of the Shy ok it passes over first some silty lake sediments and then some old moraines perched about 300 m above the valley floor at Khalsar. These may have formed when the Siachen glacier advanced the whole length of the Nubra valley, some 75 miles, and blocked the Shy ok valley, damming up a lake above the junction, just as the North Terong glacier does now on a smaller scale. Even now a high glacial trim-line can be seen on the valley-side opposite Tiggur, several hundred metres above the valley floor. At Sasoma, half-way along the Nubra valley, the old caravan track to Central Asia over the Saser la zigzags up the steep valley side, an incredible route for laden mules, and is partly cut into old moraine 300 m above the valley. Glacial striae are well preserved on some rocky surfaces, especially the small hills of volcanic rock further down the valley, which suggests that this latest major gla-ciation may have reached the small moraines at Tirit at the mouth of the Nubra valley, and be of the same age as the moraine at Leh. The older moraines and lake silts may perhaps correspond with the Indus glaciation.

Cartography

The first and only recorded ground survey of the Terong valley was done by K. S. Afraz Gul Khan, a surveyor seconded by the Survey of India to Visser's expedition in 1929. He explored the North Terong with Dr Wyss, a geologist, while Visser and Loch-matter explored the Shelkar Chorten glacier. A copy of his map at a scale of J inch to one mile (1 : 126,720) is in the Map Library at the Royal Geographical Society, London; part of this, covering the North Terong is reproduced as Fig. 3. This map also served as the basis for the small scale map accompanying Visser's paper in the G.J. (1934). (The R.G.S. also hold a copy of Visser's 1922 map of the Saser group at 1 : 100,000).

Compare this with Fig. 1, traced from a Landsat image. It is clear at once that the Visser map has major errors, and in particular it shows the glacier dividing into two large and nearly equal lobes at the top, while the tributary from the west that comes in by our ABC is only indicated by a short lobe below point 21,636 ft. Alternatively the large northwestern lobe may be a gross exaggeration of this tributary.

The route of Visser's expedition is marked on the map, but owing to the errors described above, it is not clear how far they reached; probably, I think, just west of Saigat, though possibly a short way up the tributary at ABC. In either case the spot height of 17,578 ft (5360 m) seems excessive, and any other altitudes measured from here should be regarded with caution. Anyway it is unlikely that Afraz Gul Khan could have measured the heights of peaks accurately from what appears to have been a planetable traverse. However the heights of the four highest points (underlined in my Fig. 3) on the east side of the North Terong are marked in black ink on the original map, whereas all the others are in brown. This suggests that the former were derived from some other more reliable source, presumably the Rimo glacier trigonometrical survey by de Filippi's expedition in 1912-13. Curiously however, though they clearly match four points on de Filippi's map (1923), they do not agree exactly in either position or height, differing in height by up to 10 meters.

Plants and wild life

In late June, and early July, the Nubra valley is ablaze with wild roses (Rosa webbiana); huge bushes up to 5 m high and 5 m across covered with pink flowers grow at the edges of cultivation and on rocky fans, wherever there is a little water. Later in the summer they will be covered with scarlet fruits, eaten eagerly by small boys (they have a high vitamin content).

Another distinctive characteristics of the Nubra and Shyok valleys are the thick thorny hedges which surround the fields. These are cut from Sea Buckthorn (Hippophae rhamnoides; Ladakhi Sermang), a shrub which has an mazingly wide distribution in Europe and Asia, from sea level in Britain to 4000 m in the Himalaya. Large and sometimes impenetrable thickets of this grow on the flood plains of the Nubra and Shyok valleys, and provide an important source of domestic fuel.

Once, before the valleys were inhabited, forests of Juniper Lada-khi: Shupa) probably grew in all the tributary valleys. Now there are only remnants, clinging to inaccessible rock faces, but the Terong valley is so unfrequented that we found plenty of dead wood for camp fires at the bottoms of the gullies in the ice-free valley between the Siachen and Terong glaciers.

Although at first sight this appeared a barren place with stony river terraces stretched between steep granite walls, there were quite a variety of plants: pink-flowered tamarisk bushes (Myricaria germanica; Ladakhi: Umbu); spiny cushions of Acantholimon (Lada-khi: Lonze) and Astragalus (Ladakhi: Sitchu); wild onions which our porters eagerly grubbed up with ice-axes; patches of coarse grass; and of course aromatic Artemisia (Ladakhi: Burtse) with woody root-stocks, many loads of which were carried up the Siachen glacier by early explorers for fuel. Some of our reconnaissance party, marooned here for the night by the usual afternoon rise in river level, with no matches or food and only thin clothes, were reduced to stuffing their clothes with dry grass to try to keep warm. It is even rumoured that as they lay shivering in the middle of the night one of them was detected surreptitiously transferring grass from a companion's shirt to his own! On the glacier itself there were occasional plants of bright purple-flowered willow-herb (Epilobium) rooted in the thin moraine.

When the Workmans explored the Siachen they saw many ibex and a huge pile of old horns. We saw a few of their tracks and what may have been snow-leopard tracks, but no animals. We only saw a few birds. In the Nubra valley flocks of yellow-legged choughs scavenge round the army camps, and at our ABC these were replaced by a pair of very conversational and tame but rather disreputable looking ravens who visited us daily. The highest small bird I saw was I think a wall-creeper at the foot of Saigat (c. 5500 m).

REFERENCES

1. de Filippi, F. 1923 'Storia della spedizione scientifica italiana nel Himalaia Caracorum e Turchestan Cinese (1913-1914)'. Bologna.
2. Ruck, O. L., 1934 Spoke in discussion of Visser's paper, 1934. Geographic Journal 84, p. 292.
3. Shi Yafeng and Others, 1979, "The Batura Glacier in the Karakoram Mountains and its variations'. Scientia Sinica 22, pp. 958-974.
4. Visser, P. C, 1934 "The Karakoram and Turkistan Expedition of mS-lOSO*. Geographic Journal 84, p. 281-292.
5. Workman, W. H., 1914 'Nieve penitente and allied formations in the Himalayas'. Zeitschr. fur Gletscher-Kunde, 8, pp. 289-330.

 

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