Western Himalaya and Tibet Part 9

Notwithstanding the considerable elevation, I noticed but little in the vegetation different from that common in Piti. The forms were by no means so alpine as on the pa.s.ses between Kunawar and Hangarang, though the elevation was greater than on any of these. It was probably owing to the aridity of the climate that the flora, at elevations of 15,000 feet, instead of being composed of delicate alpine plants, was much the same as it had been 4000 feet lower. The rose, the common _Rhamnus_ of Piti, a little shrubby _Potentilla_, a spinous _Astragalus_, and several _Artemisiae_, were the common shrubs, and two species of rhubarb grew abundantly on the dry hills above Kibar. The _Dama_, which shuns the level country, the _Allium_ first observed the day before, and _Lamium rhomboideum_ of the Hangarang pa.s.s, were almost the only striking plants observed; all the others were those of the ordinary flora of the dry hills and gravelly plains of the Piti valley. It is necessary, of course, in comparing this vegetation with that of the pa.s.ses, to recollect that we were here in a valley, on slopes surrounded on all sides by lofty ridges, not on the summit of a range overlooking everything around, or only surpa.s.sed a very little by the continuation of the same ridge; so that the temperature of the summer months must be considerably higher than on the more exposed though less elevated pa.s.ses.

[Sidenote: ROCKY GORGE.

_September, 1847._]

Further on, the road descended rapidly to the stream, which flowed in a rocky gorge, through which we held our course for three miles. A few willows, and stunted shrubs of _Myricaria_, occurred on the descent, and the willow was found occasionally on the banks of the stream in the gorge, which was enclosed by high and steep limestone rocks on both sides. These gradually contracted as we advanced, but again expanded at the point where we encamped, which was close to the bank of the stream. The ravine being now more open, we could see the hills to better advantage, and were struck with astonishment at the desolation by which we were surrounded. We were, in truth, in a wilderness of rocks, which to the south closed together, so as to shut in the ravine by which we had ascended. High walls of cliffs rose on either hand to an elevation of at least 1500 feet, displaying a natural section of a mult.i.tude of strata, which seemed to be repeated again and again in a succession of beds of limestone and slate. The elevation of our encampment was 14,800 feet.

On the 7th of September, the wish of our guides and porters according with our own, we did not cross the Parang pa.s.s, which was still five miles distant, and nearly 4000 feet above us, but contented ourselves by ascending to the highest water, perhaps 1500 feet below the summit.

We ascended on a steep s.h.i.+ngly ridge to the right of the stream where we had pa.s.sed the night. Tufts of _Lamium rhomboideum_ grew among the loose s.h.i.+ngle, but no other plant seemed to vegetate in such an ungenial soil. When we had pa.s.sed from the s.h.i.+ngle, which was confined to the base of the ascent, the ridge was dry and gravelly, with tufts of _Dama_ and of a species of nettle. Above 16,500 feet, the spur was rocky and uneven, and some alpine vegetation was observed, for which I conjecture that the melting of the snow had probably supplied moisture, as lower down the sterility had been complete. About fifteen species were collected, two _Potentillae_, _Biebersteinia odora_, a _Lychnis_, a little tufted saxifrage, and species of _Nepeta_, _Artemisia_, _Gnaphalium_, _Saussurea_, _Allardia_, _Polygonum_, _Rheum_, _Blitum_, one gra.s.s, and a fern. Three or four lichens grew on the stones, and I obtained one specimen of a moss without fructification. The _Allardia_, a pretty little rose-coloured flower, with an agreeable smell, was the only new species; all the others were already familiar to me. They grew in the crevices of the rocks, in extremely small quant.i.ty, struggling as it were for existence against the unfavourable circ.u.mstances to which they were exposed.

[Sidenote: ASCENT TOWARDS THE PARANG Pa.s.s.

_September, 1847._]

A stony ravine, elevated about 17,000 feet, was the place selected for our encampment. A small stream, supplied by a patch of snow a little way above, trickled down under the angular gravel. The ascent had been extremely fatiguing, because almost without intermission, and we were glad of rest on reaching that elevation. During the day, however, I ascended a ridge of rugged rocks, which rose above our tents to a height of more than 500 feet, being desirous of ascertaining to what elevation I should find vegetation. An _Alsine_ was common among the gravel, with two small plants which were not in a determinable state; and on the rocks, to the highest level to which I succeeded in ascending (probably 17,600 feet), the little _Allardia_ continued to occur occasionally. The ridge afforded a good view of the mountains round. The range to the north, which we had still to cross, lay in a semicircle behind; to the east was the continuation of the ridge by which we ascended; and a deep hollow lay to the west. Rugged rock everywhere met the view. The slates which alternated with the limestone were so very brittle that they everywhere formed piles of angular fragments, which filled all the hollows, and formed a sloping talus against every precipice. The view was one not to be forgotten, its desolation far surpa.s.sing any conception of waste and utter barrenness which I could have formed.

During the whole day I was never free from a dull headache, evidently caused by the great elevation. Rest relieved it, but the least exertion brought it back again. It continued all evening, as long as I was awake, and still remained in the morning of the 8th, when I rose soon after daybreak to prepare for the journey. A few paces took us beyond the s.h.i.+ngly ravine in which we had been encamped, and the remainder of the ascent was throughout over loose angular fragments, the _debris_ of the cliffs on the right. Under the latter we pa.s.sed, winding round the side of the semicircular bay, till we got to about its centre, when the ascent became excessively steep and toilsome. The exertion of raising the body was very fatiguing, and the last few hundred yards were only accomplished after many pauses. A few large patches of snow lay in hollows along the road; but up to the very crest of the pa.s.s there was no trace of perpetual snow, nor even any continuous snow-bed.

[Sidenote: THE PARANG Pa.s.s.

_September, 1847._]

The summit of the Parang pa.s.s is a narrow ridge, covered with large blocks of stone. To the north lay a large field of snow, sloping downwards at a very gentle angle. In this direction the view was limited within two miles by steep rugged mountains, which closed in on both sides. To the right and left also, the pa.s.s was overlooked by ridges close at hand. The only direction in which a distant view was obtained was south, where the mountains beyond the Piti river were beautifully seen: from the great elevation at which we stood, their summits were everywhere in view; their elevation was surprisingly uniform, and the whole range was capped with snow. The mountains close at hand presented much the same appearance as I had seen from the rocks above our encampment the day before.

[Sidenote: GLACIER.

_September, 1847._]

I reached the summit of the pa.s.s, which has an elevation of 18,500 feet, at a quarter before eight in the morning. At that time the temperature was 28; and a cold southerly wind blew with considerable violence, making us seek the shelter of the blocks which lay around. A small red lichen, (_Lecanora miniata_,) on the fragments of rock, was the only vegetable production I observed. After an hour's rest, we commenced the descent over the snow-bed, proceeding towards a gap which was visible in the mountains. The snow was hard frozen, and crisp under the feet. Descending steadily without any fatigue, we were soon evidently on a snow-covered glacier. A few fissures were pa.s.sed, but mostly not above a few inches wide, and none that we could not with ease step over, the widest not exceeding two feet. At a distance of about a mile and a half from the crest, the mountains, which on both sides surrounded the snow-bed in the form of a circle, had so much approached to one another, that they formed a narrow valley, down which the snowy ma.s.s continued in the form of a rugged glacier.

We now left the surface of the ice, and proceeded along the stony side of the ravine, with the glacier on our left hand, and steep limestone rocks on our right. Blocks of limestone strewed our path as we descended, and numerous small fragments of the same rock covered the edge of the glacier.

About three miles from the summit of the pa.s.s the glacier terminated abruptly in a bluff precipice, the height of which was more than 100 feet. Little rills of water were, at the time we pa.s.sed (9 A.M.), trickling from every part of the surface, and a small streamlet ran along the edge of the glacier under an arch of ice. The structure was here very evident: broad white bands, and narrower ones of a dirty colour, from the earthy matter which they had absorbed, ran parallel to the slope of the ravine, the arches or loops (so well explained by Professor Forbes in his delightful work on the glaciers of the Alps) being drawn out to a great length.

At the termination of the glacier, we descended from the steep mountain-side, along which we had hitherto travelled, to the flat plain, the continuation of the surface on which the glacier rested. On this descent the first vegetation appeared at an elevation of about 16,500 feet. Two small gra.s.ses, _Biebersteinia odora_, a _Lychnis_, and a little villous _Astragalus_, were the plants observed: they grew in the crevices of the rock, and scarcely rose above the ground. None of the species were different from those collected in the mountains of Piti.

[Sidenote: THE PARANG VALLEY.

ITS VEGETATION.

_September, 1847._]

When we had reached the middle of the valley, so as to be exactly in face of the glacier, we found that a large stream issued from a vaulted cavity at its termination. For some hundred feet the stream ran among large ma.s.ses of ice, as if the glacier had very recently extended further, and had melted away irregularly, leaving these ma.s.ses standing. Leaving the glacier, we still followed the valley, which was confined on both sides by steep cliffs. We kept close to the stream, walking over its gravelly bed, and I collected a few more plants as I descended; none, however, new to me. A little _Nepeta_, four species of _Potentilla_, a _Gnaphalium_, several gra.s.ses and _Carices_, and a very small fern, were the species. About three miles from the end of the glacier we found our tents pitched on a small plain, connected with a lateral ravine, and covered with tufts of _Dama_, and a little species of _Alsine_ in flat tufts, which was quite new to me. The elevation of our encampment was 16,000 feet.

We followed the course of the valley into which we had thus descended, for three days, without meeting with any inhabitants, and through so uniform a country, that it is unnecessary to detail each day's journey. Rugged and rocky mountains, of moderate elevation, princ.i.p.ally limestone, bounded the view on both sides. In front we seldom saw more than a few miles; and behind, the view was in general equally limited, though occasionally we could see, up a lateral valley, the peak of a snowy mountain. The valley was almost invariably wide and level, once or twice only interrupted by projecting ridges of low rocks advancing to its centre. Low platforms of alluvium, like those of Piti, occupied the wider parts, their upper angles resting (as in Piti) on the opening of lateral ravines, while their bases were cut into cliffs by the stream.

During these three days we descended from 16,000 to about 14,800 feet.

The surrounding mountains were quite barren and desolate. The gravelly plains were covered with tufts of _Dama_ and of the curious tufted _Alsine_, which formed dense flattened ha.s.sock-like ma.s.ses, of considerable size. The soil was very saline, and as we descended it gradually became more so. In the earlier part of the descent, the alpine forms were the same as those to the south of the Parang pa.s.s, and the plants were few in number and much scattered. Lower down, however, more novelty was met with. A little willow was the first shrubby plant, and was followed by _Ephedra_, _Myricaria_, and _Hippophae_, all much stunted. Still lower there were large patches of green-sward along the stream, generally swampy, and always covered with a saline incrustation. _Artemisiae_, _Astragali_, _Gentianae_, and _Potentillae_, were the commonest forms, with a number of saline plants, chiefly _Chenopodiaceae_, which abounded on the lowest spots.

On the 11th, the last of these three days, the vegetation had quite lost its alpine character, notwithstanding that the elevation was still 15,000 feet. No _Biebersteinia_ was seen, and the little species of _Potentilla_, _Alsine_, _Saxifraga_, _Cruciferae_, and _Parna.s.sia_, were no longer met with. The large _Hyoscyamus_ of Piti (_Belenia_ of Decaisne) had made its appearance, with tall _Artemisiae_, a _Clematis_, a rank-growing _Corydalis_, _Cicer Soongaric.u.m_, and other plants in no way alpine. I was much surprised to observe so complete a change in so moderate a descent, and very much interested to find that the alpine flora had so completely disappeared. I regret that I am as yet unable to give my results in more perfect form, the necessary comparison and determination of the species collected still remaining to be done.

[Sidenote: CHUMORERI.

_September, 1847._]

During our descent we had gradually taken a more easterly course, and on the 11th our direction was nearly due east. On this day we pa.s.sed the gorge in the mountains, up which the road turns to the Chumoreri lake, by which Mr. Trebeck had travelled to and from Ladakh. This would have been our most direct route to Le, but we were desirous of visiting the more eastern districts, so as to reach the Indus as soon as possible. The mountains in this gorge suddenly lowered; a wide gravelly plain sloped gently up to a low ridge, which did not appear to rise higher than two or three hundred feet above the level of the Parang river. Beyond this ridge, on the a.s.surance of our guides, confirmed by Major Cunningham, who had on a former occasion travelled along the Chumoreri lake as far as its southern extremity, lies the lake, without any more considerable elevation separating it from the Parang river.

It is much to be regretted that the late period of the season, and the other important objects which we had to accomplish, should have prevented us from crossing this narrow neck of land. It would probably have thrown much light upon the question of the origin and nature of the salt lakes, which are, as is well known, scattered over Tibet, Central Asia, and Siberia. The Chumoreri lake has certainly no outlet, but from the nature of the surrounding mountains, everywhere steep and lofty, there can be no doubt that at one period its waters were discharged at its south end by the narrow valley which we saw from the south side of the Parang river[12]. An accurate determination of the height of the separating ridge above the present surface of the lake, a careful examination of the configuration of the surface at its southern end, and an a.n.a.lysis of the water, which is described as sufficiently brackish to be unpleasant though not absolutely undrinkable, would certainly enable conclusions to be drawn as to the nature of the cause which has lowered the level of the waters of the lake, and so put an end to its discharge.

[Sidenote: WILD HORSE.

_September, 1847._]

In the plain which sloped gently upwards from the Parang river towards the Chumoreri lake, we saw for the first time a Kiang, or wild horse, but at too great a distance to enable his shape and appearance to be distinctly made out; and the river, which was interposed between us, prevented our approaching nearer. We afterwards frequently saw these animals, but from their extreme wariness, and the open nature of the country, we were never fortunate enough, notwithstanding repeated trials, to get within gunshot distance of them. They appear to abound at elevations between 14,000 and 16,000 feet, on the open undulating tracts on the summits of the mountain ranges, and to avoid valleys and rocky districts, where they would be liable to surprise.

[Sidenote: THE PARANG VALLEY.

_September, 1847._]

To the eastward of the former outlet of the lake, the valley of the Parang river was more contracted than it had been in any previous part of its course. Rocky hills, projecting from the southern mountains, advanced so close to the river, that no pa.s.sage was practicable along their base, and the road several times ascended several hundred feet to cross these ridges. This obstruction was, however, but temporary, lasting only for a few miles, beyond which the valley expanded into a very wide plain, extending for five or six miles in an easterly direction, by about half that distance from north to south. The borders of this wide expanse were very low platforms, almost horizontal, and not more than from six to ten feet above the river.

The middle portion was a plain of gravel, scarcely higher than the level of the stream, and evidently occasionally submerged. Here the river bends rapidly round towards the south-east. The district at which we had now arrived is called Chumurti, and about eight or ten miles to the east of our encampment on the 11th of September, is a village or a.s.semblage of tents called Chumur, from which we obtained a supply of porters, to relieve the party who had accompanied us from Piti. Here also, in accordance with the instructions we had received on leaving Simla, Captain Strachey left us, with the intention of following the course of the Parang river, as far as he conveniently could, and then turning to the left across one of the pa.s.ses of the great trans-Sutlej chain to the Indus. Major Cunningham and myself, on the other hand, proposed to proceed by the direct, and equally unknown, route to Hanle, and thence to visit the Indus, and proceed to Le.

[Sidenote: THE PARANG RIVER.

_September, 1847._]

The Parang river, whose source is in the mountains immediately north of the Parang pa.s.s, has, as we have seen, at first a northerly direction, but gradually bends more and more to the eastward and southward, and finally has a nearly south-west course, where it joins the Piti river, nearly opposite s.h.i.+alkar. Its source, as well as its confluence with the Piti river, are within the British territory; but the most important, because the most populous, part of its course lies within the Chinese border. The boundary of the Chinese district runs nearly from north-east to south-west, pa.s.sing a little to the west of Rodok, and crossing the Indus at the village of Chibra, where Mr.

Trebeck was stopped in his attempt to penetrate up the Indus; thence a little south of Haule, and across the course of the Parang river. It then bends more towards the south, and again crosses the Parang at the point where we were stopped in the end of August, whence its direction is nearly due south as far as Nilang, on the Jahnavi branch of the Ganges.

The Parang river being a tributary of the Sutlej, by crossing the great chain at the Parang pa.s.s we had not reached the Indus valley, but had descended into a lateral valley still connected with the drainage of the Sutlej. The great line of watershed between the Indus and Sutlej lay still before us. This chain, which is the prolongation of Kailas, must be called the trans-Sutlej Himalaya, unless the name Himalaya be restricted to the chain south of the Sutlej, in which case the mountains of Lahul, Kishtawar, and Kashmir, would lose their claim to that appellation.

[Sidenote: ASCENT TOWARDS LANAK Pa.s.s.

_September, 1847._]

Towards this chain, which we were to cross by the Lanak pa.s.s, we commenced our journey on the morning of the 12th of September. Our road lay across the Parang river, which flowed in several channels among the wide expanse of gravel which here formed its bed. The morning was bitterly cold, and the water almost icy, to the great discomfort of our porters. The largest stream was perhaps twenty-five feet wide and two and a half deep, with a moderately rapid current.

After crossing the river we took a northerly direction, leaving the valley or plain of the Parang river, and ascending an open, almost level valley, bounded by low hills. The mountains on the left, which were interposed between our route and the Chumoreri lake, were the most rugged in sight. In the centre of the plain was the channel of a stream, very s.h.i.+ngly, but without water, along which, or on alluvial banks only a few feet higher, we gradually advanced. The level of our camp on the Parang river had been 14,800 feet; and from this we were now gradually but imperceptibly rising. The hills on either hand were rounded and low, but increased in height as we receded from the Parang river. The soil was very barren, and showed many indications of salt.

Scattered plants of _Salsola_ were common, with _Christolea_, a pretty Cruciferous plant, with purple flowers and fleshy wedge-shaped leaves, tasting strongly of horse-radish, which has been described by Decaisne from specimens collected by Jacquemont in Piti. A little white _Alyssum_, which I had not previously met with, was also very common.

Four miles from the Parang river we reached a flat gra.s.sy plain of considerable extent, with deep black soil, in which meandered a very slowly running stream, perhaps twelve feet wide, which seemed to have an outlet by an open valley on our right, and to join the Parang some miles to the east of where we left it. A great part of this plain was swampy, the turf rising in little knolls, but round the edges and in all the higher parts it was covered with a thick incrustation of white efflorescent salt. To the north and east, low gently-sloping hills as barren as ever rose from the edge of the green plain; and in the north-east corner, close to the foot of the hills, a large fountain, discharging copiously clear tasteless cold water, was evidently the source of the stream which flowed over the plain. The gra.s.sy turf produced a considerable number of plants, not a few of which were new to me. An _Umbellifera_, an _Aster_ with large purple flowers, a _Saussurea_, and two species of _Pedicularis_, one with white, the other with yellow flowers, were very common, as were also a species of _Triglochin_, a white _Juncus_, several _Carices_, and three or four very beautiful gra.s.ses. In the shallow water of the pools scattered over the plain, a species of alga was common, floating without attachment. It was a broad foliaceous green plant, and has been determined by the Rev. M. J. Berkeley to be a species of _Nostoc_, closely allied to, if not identical with _N. commune_, a species which occurs in all parts of the globe.

After crossing this plain, and stopping to rest by the fountain, we began to ascend the long slopes of the hills, partly on a level ridge, partly along the wide sloping valleys by which the low hills were separated. Both hills and plain were frightfully arid, the aspect of the country being of an uniform grey colour; and coa.r.s.e gravel, with scattered stones of larger size, everywhere covered the surface. The ascent was very inconsiderable till towards the end of the day's journey. The distance travelled was about ten miles, and we encamped at about 15,800 feet, on the left bank of a small stream which descended from the north, the borders of which were swampy and covered with green turf, in which the common plants of the country occurred, such as little gentians, _Ranunculi_, _Parna.s.sia_, several _Polygona_ and _Potentillae_, _Carices_, and gra.s.ses. On the west bank of the stream was a low ridge of clay-slate rocks, while on the right and in the valley was a heap of granite boulders; no doubt an ancient moraine, for the fragments were piled on one another to a great height, and rose far above the stream as well as the ordinary level of the plain.

[Sidenote: LANAK Pa.s.s.

_September, 1847._]

On the 13th of September we crossed the Lanak pa.s.s, which lay before us at a distance of about five miles. From our encampment the mountains appeared easy of access and rounded in outline, and we commenced the ascent by a nearly level walk across the gravelly plain.

After a mile and a half we rejoined the stream, and kept along it for a little way. Its banks were green with a narrow belt of turf; and the bed was often rocky, the rock being still clay-slate, notwithstanding the granite boulders everywhere scattered about. The edges of the stream were frozen, spiculae of thin ice adhering to the herbage. The vegetation was quite alpine, the elevation being certainly above 16,000 feet. A _Delphinium_, which seemed the same as the _D.

Brunonianum_ of the Hangarang pa.s.s, a little yellow saxifrage, and a white-flowered species of the same genus, which I believe to be the Scottish alpine _S. cernua_, an entire-leaved yellow _Ranunculus_, a _Pedicularis_ with purple flowers, and some gra.s.ses, were the most remarkable plants observed.

After a mile, we left the ravine and ascended to the open gently-sloping ground on its left, still rising sensibly as we advanced. The surface was, as usual, dry and gravelly, and _Oxytropis chiliophylla_ and a little _Stipa_ were almost the only plants. We continued nearly parallel to the ravine, and crossed it again a little further on. It was now dry, and its steep stony banks were covered with bushes of _Dama_. Still gradually ascending, we crossed the same ravine a third time, where its bed was upwards of 17,000 feet. There was again no water visible, but the ground was still moist, the streamlet probably, as is very general in these arid regions, trickling under the surface among the loose gravel. The little alpine nettle, which I had first found on the northern spurs of Porgyul, near Changar, and again on the southern face of the Parang pa.s.s, was here common, as were two species of _Alsine_, which formed dense tufts. A little saxifrage and the _Delphinium_ were also still observed, but all the other plants had disappeared.

Leaving the ravine for the last time, we continued the ascent, which became steeper as we advanced. A rounded ridge lay to our right hand, and we rose nearer and nearer to its crest. Fragments of granite, piled on one another in increasing numbers, covered the steep slopes.

Rock _in situ_ was only to be seen in one place; it was still clay-slate, containing a good deal of mica. The top of the pa.s.s was nearly level for several hundred yards, and covered with boulders, princ.i.p.ally of granite, but a few of quartz and of a trappean rock, quite black and h.o.m.ogeneous. The outline of the mountains was generally rounded, and they rose gradually in both directions above the pa.s.s, which had an elevation of 18,100 feet. The view, both towards the direction in which we had come and that in which we were proceeding, was rather extensive, but from the prevailing uniformity of outline and colour it was more striking than beautiful. There were no trees or villages, no variation of surface greater than an occasional grey rock, but everywhere the same dreary sterile uniformity. Nothing could be seen of Lake Chumoreri, which lies at least fifteen miles westward, and is surrounded by mountains, everywhere (except in the direction of the former outlet) higher than that on which we stood.

The occurrence of great acc.u.mulations of boulders, of a rock different from that which occurs _in situ_ on the very summit of the pa.s.s, was quite conformable to what I had observed on some of the pa.s.ses between Kunawar and Hangarang. It was not, however, on this account the less puzzling, nor was it till I crossed the Sa.s.sar pa.s.s, in August, 1848, that I could at all conceive in what way it was to be explained. On this pa.s.s, as I shall afterwards relate in detail, a glacier occupies the crest of the pa.s.s, descending from higher mountains to the north, and presenting a bluff termination in two directions.

On the summit of the pa.s.s I collected specimens of three phenogamous plants, probably nourished by a recently melted patch of snow; for though there was none on the pa.s.s itself, nor on the descent on either side, a steep mountain, half a mile to the right, in a due northern exposure, was still covered with snow to at least five hundred feet below the level of the pa.s.s. The small quant.i.ty of snow seen in the distant view was very remarkable, and the more so as there was no indication of diminished elevation; ridge rising beyond ridge, and peak behind peak, to the utmost limits of view. The three plants which were observed were a little _Arenaria_ or _Stellaria_, and two Cruciferous plants, one of which only was in fruit. A red lichen, the same as that seen on the Parang pa.s.s, covered the stones.

The descent from the Lanak pa.s.s was at first gentle, but very soon became steep, to the bottom of a valley in which a small stream of water was running, derived, I suppose, from some small snow-beds in a lateral ravine out of sight, for it almost immediately disappeared under the gravel. Soon after leaving the crest of the pa.s.s, we came upon clay-slate rock finely laminated, and dipping south-south-west at a high angle. The valley by which we descended gradually contracted into a rocky ravine, at last very narrow, with high precipitous walls, and full of large boulders. We encamped for the night at its junction with a large stream descending in a rocky dell from the west. Around our camp, on both sides of the stream, there was an outbreak of greenstone, which had upheaved the clay-slate rocks.