Turnips are grown at Palung during the short stay of the people, and this is the most alpine cultivation in Sikkim: the seed is sown early in July, and the tubers are fit to be eaten in October, if the season is favourable. They did not come to maturity this year, as I found on again visiting this spot in October; but their tops had afforded the poor Tibetans some good vegetables. The mean temperature of the three summer months at Palung is probably about 40°, an element of comparatively little importance in regulating the growth and ripening of vegetables at great elevations in Tibetan climates; where a warm exposure, the amount of sunshine, and of radiated heat, have a much greater influence.
During the winter, when these families repair to Kambajong, in Tibet, the flocks and herds are all stall-fed, with long grass, cut on the marshy banks of the Yaru. Snow is said to fall five feet deep at that place, chiefly after January; and it melts in April.
After tea, I ascended the hills overhanging the Lachen valley, which are very bare and stony; large flocks of sheep were feeding on them, chiefly upon small tufted sedges, allied to the English Carex pilularis, which here forms the greatest part of the pasture: the grass grows mixed with it in small tufts, and is the common Scotch mountain pasture-grass (Festuca ovina).
On the top of these hills, which, for barrenness, reminded me of the descriptions given of the Siberian steppes, I found, at 17,000 feet elevation, several minute arctic plants, with Rhododendron nivale, the most alpine of woody plants. On their sterile slopes grew a curious plant allied to the Cherleria of the Scotch Alps, forming great hemispherical balls on the ground, eight to ten inches across, altogether resembling in habit the curious Balsambog (Bolax glebaria) of the Falkland Islands, which grows in very similar scenes.[[202]]
[202] Arenaria rupifraga, Fenzl. This plant is mentioned by Dr. Thomson (“Travels in Tibet,” p. 426) as common in Tibet, as far north as the Karakoram, at an elevation between 16,000 and 18,000 feet. In Sikkim it is found at the same level. Specimens of it are exhibited in the Kew Museum. As one instance illustrative of the chaotic state of Indian botany, I may here mention that this little plant, a denizen of such remote and inaccessible parts of the globe, and which has only been known to science a dozen years, bears the burthen of no less than six names in botanical works. This is the Bryomorpha rupifraga of Karelin and Kireloff (enumeration of Soongarian plants), who first described it from specimens gathered in 1841, on the Alatau mountains (east of Lake Aral). In Ledebour’s “Flora Rossica” (i. p. 780) it appears as Arenaria (sub-genus Dicranilla) rupifraga, Fenzl, MS. In Decaisne and Cambessede’s Plants of Jacquemont’s “Voyage aus Indes Orientales,” it is described as Flourensia cæspitosa, and in the plates of that work it appears as Periandra cæspitosa; and lastly, in Endlicher’s “Genera Plantarum,” Fenzl proposes the long new generic name of Thylacospermum for it. I have carefully compared the Himalayan and Alatau plants, and find no difference between them, except that the flower of the Himalayan one has 4 petals and sepals, 8 stamens, and 2 styles, and that of the Alatau 5 petals and sepals, 10 stamens, and 2-3 styles, characters which are very variable in allied plants. The flowers appear polygamous, as in the Scotch alpine Cherleria, which it much resembles in habit, and to which it is very nearly related in botanical characters.
A few days afterwards, I again visited Palung, with the view of ascertaining the height of perpetual snow on the south face of Kinchinjhow; unfortunately, bad weather came on before I reached the Tibetans, from whom I obtained a guide in consequence. From this place a ride of about four miles brought me to the source of the Chachoo, in a deep ravine, containing the terminations of several short, abrupt glaciers,[[203]] and into which were precipitated avalanches of snow and ice. I found it impossible to distinguish the glacial ice from perpetual snow; the larger beds of snow where presenting a flat surface, being generally drifts collected in hollows, or accumulations that have fallen from above: when these accumulations rest on slopes they become converted into ice, and obeying the laws of fluidity, flow downwards as glaciers. I boiled water at the most advantageous position I could select, and obtained an elevation of 16,522 feet.[[204]] It was snowing heavily at this time, and we crouched under a gigantic boulder, benumbed with cold. I had fortunately brought a small phial of brandy, which, with hot water from the boiling-apparatus kettle, refreshed us wonderfully.
[203] De Saussure’s glaciers of the second order: see “Forbes’ Travels in the Alps,” p. 79.
[204] Temperature of boiling water, 183°, air 35°.
The spur that divides these plains from the Lachen river, rises close to Kinchinjhow, as a lofty cliff of quartzy gneiss, dipping north-east 30°: this I had noticed from the Kongra Lama side. On this side the dip was also to the northward, and the whole cliff was crossed by cleavage planes, dipping south, and apparently cutting those of the foliation at an angle of about 60°: it is the only decided instance of the kind I met with in Sikkim. I regretted not being able to examine it carefully, but I was prevented by the avalanches of stones and snow which were continually being detached from its surface.[[205]]
[205] I extremely regret not having been at this time acquainted with Mr. D. Sharpe’s able essays on the foliation, cleavage, etc., of slaty rocks, gneiss, etc., in the Geological Society’s Journal (ii. p. 74, and v. p. 111), and still more so with his subsequent papers in the Philosophical Transactions: as I cannot doubt that many of his observations, and in particular those which refer to the great arches in which the folia (commonly called strata) are disposed, would receive ample illustration from a study of the Himalaya. At vol. i. [p. 309,] I have distantly alluded to such an arrangement of the gneiss, etc., into arches, in Sikkim, to which my attention was naturally drawn by the writings of Professor Sedgwick (“Geolog. Soc. Trans.”) and Mr. Darwin (“Geological Observations in South America”) on these obscure subjects. I may add that wherever I met with the gneiss, mica, schists, and slates, in Sikkim, very near one another, I invariably found that their cleavage and foliation were conformable. This, for example, may be seen in the bed of the great Rungeet, below Dorjiling, where the slates overlie mica schists, and where the latter contain beds of conglomerate. In these volumes I have often used the more familiar term of stratification, for foliation. This arises from my own ideas of the subject not having been clear when the notes were taken.