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

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THE DOK-CHU VALLEY.

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At Tangna the height is 4 038 m. The fall of the valley is therefore not steep, although steeper than that of the Tsangpo. The Dok-chu forms a series of rapids amongst small granite blocks; but the rapids alternate with quiet, deep, and broad stretches; at some places the river is so much as 7o m broad, at the rapids only 20 or even 10 m. The greatest depths measured in the river were now 1,60 and 1,75 m. At some places the river is divided into two branches. The volume of water amounted, on April 6th, to 33 cub. m. a second. The Dok-chu is said to be at its highest in the end of July and beginning of August, that is during the rainy season. The pulsations of the river entirely depend upon the rains; in April the water-level is low. During the winter the river is covered with ice, at most places sufficiently strong to bear the weight of a man.

At Tangna there thrive a few poplar trees; peas, wheat and barley are cultivated, but the harvest is regarded as unsatisfactory and uncertain. From N. 15° E. the valley Naga comes down and from N.E. Dupda, both having one and the same mouth, and each carrying a brook; they are very short, not even one day's journey; in their background, however, considerable mountains are visible. Quite near, and N. 37° W. from Tangna is a mountain called Ponyung, and to the left of it, or in N. 55° W., is Pochung-seshung, a valley from the north. To the N. 63° W. we notice the mountains of Shakya, and to the west mount Chepo-richen. The southwestern mountains are called Dambo-richen, along the foot of which the Dok-chu flows, just south of the village. Grey granite prevails in the whole region. Round granite blocks are extremely common all around the village and in the mouths of the Naga and Dupda. The road westwards from Tangna proceeds amongst such blocks and along fluvial terraces, cut through by many dry ravines; only Lung-sang had a brook, crossed on a bridge.

Sanga-pu is a valley from the south. The river Dok-chu goes as a rule along the southern or right side, only occasionally touching the northern, or following the gravelly bed in the middle. A part of the road goes amongst hills of clay, ravines, terraces, and accumulations of fine detritus products from the granite; the valley is rather narrow and irregular. Along the western banks of the ravines there are ordinarily rudimentary dunes of sand. The tributary valleys from the north are longer than those from the south; their sources cannot always be seen, but often the crest from which they come, that is to say either the Nien-chen-tang-la itself or a ramification from the same. On the other hand the origin of the southern tributaries is always visible just under the crest of the range which is situated between the Dok-chu and the Tsangpo. The northern slopes of that range are partly covered with snow. One of the valleys from there is called Sangdo-pu.

The valley of the Dok-chu is thus bounded by two ranges, the crests of which are not far from each other. The crest of the southern is, however, nearer than that of the northern, and therefore the mountain slopes, at the left side of the valley,

are more gradual and moderate.

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