国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

THE ENTRANCE OF THE MU-CHU VALLEY.

269

The name Raga-tsangpo is hardly known at Lingo; the joint river, as well as the western river, are both called Dok-chu. Generally the natives have very diffuse ideas about the origin of the rivers. Asking where the sources of the Mü-chu are situated, one gets the answer: in the Chang-targo mountains, which means: in the Targo-gangri of the north.

Remembering the orography of the first crossing, where Dangbä-la is situated

in a range which for good reasons I regard as the western continuation of the Nienchen-tang-la, and thus on the water-parting between Bup-chu-Mü-chu and Rong-chu, one could not expect to find any considerable tributaries to the Mü-chu from the east, until many days' journey northwards. Such is also the case; the main valley is very sharp cut, the tributaries insignificant. The Mil-chu valley is narrower than that of the Dok-chu, as the Mü-chu is a transverse valley, piercing ranges, whereas the Dok-chu is situated between and parallel with two ranges.

In the lowest part of its course the Mü-chu keeps to the right or western side

of its valley; at its left side heaps of big granite blocks are spread at the foot of the rocks; only just before joining the Dok-chu the river crosses its valley diagonally to the left side and flows along and amongst the blocks. So far as the Dokchu or Raga can be seen westwards it also keeps to the right side of its valley. The two last southern tributaries to the Dok-chu are Pangyu and Dachii, and the last northern is Sangi.

In the Mü-chu small rapids alternate with deep, broad and quiet sections,

and the general fall is slow. Sometimes the road keeps some i o or 20 m above the bottom of the valley, sometimes on the top of the left side terrace. Chisu is a valley from the east, Ok-tsangma a part of the main valley with barley fields protected by a stone wall; Kao-chirang is a valley from the west, as usual, short and steep; Pukpe-taglung is a grotto at the left side of the valley, Kabu a wide but short valley from the west, with a brook. The valley of the Mü-chu is here very regular; it sometimes looks almost like an artificial channel. The breadth is about 35 m. An iron chain bridge, called Tokcha or Ducha, crosses the river here. Narrow belts of ice follow both banks at one metre above the present level of the river, indicating a considerable fall of the water. At the right side of the valley, below the mouth of the Kabu, the erosion terrace has a height of some 3o m. From the east enters the valley Taka. Grey granite prevails the whole way, sometimes interrupted by diabas-porphyrite or schist.

At Tagmara and higher up the river has mighty terraces on both sides. The valley is deep cut and well worked out by the river. The mountain masses east and west are of the same moderate height, but compact and solid. Ege-tang is a ridge of quartzitic schist, above which the granite crops out again.

Finally Changulung enters from the west and Tongdung-pu from the east; in the mouth of the latter there is a juniper of unusual dimensions. From N. 3o° E. enters the valley Tongchen-pu. Tong is the name of the whole region round Camp