IIIFカラー高解像度
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
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| IIIFカラー高解像度 |
| Southern Tibet : vol.3 | |
| 南チベット : vol.3 |
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引用情報
248
THE FIRST CROSSING.
~n
the same height prevails all over the Chang-tang. Thus Richthofen's law regarding the difference between central and peripheric countries may be easily observed even within the boundaries of Tibet proper.
As all the lakes, from Tarok-tso to Tengri-nor, are practically on the same height, the small differences in height between the starting points of our eight lines do not play any important part. On our first line the difference of height between the Chang-tang, Ngangtse-tso, and the Tsangpo amounts to 764 m. This is the depth, on this section, to which the river has worked out its bed through the crust of the earth. And this is the value which is going to decrease gradually to
the west.
Considering our first line of crossing I believe the best plan will be to divide it into two parts, both starting from Sela-la. Thus the orographical and hydro-graphical arrangement will be more clearly understood.
The culminating pass on the first line is generally called Sela-la, although I heard the name pronounced Sela and Tselal or Tselal-la as well. One guide called it Chang-la or Pod-la, but the combination of these two words seems rather to be a nomen aftpellativurn, for all the water-parting passes on the eastern half of the Transhimalaya are regarded as Chang-la-Pod-la's, i. e. passes between Chang or Chang-tang and Pod or Pö, Tibet proper.
It seems likely that the Sela-la should be situated in the same range as the Khalamba-la, but it should be remembered that we have no proof whatever that such is the case. For between Khalamba-la and Sela-la there is a perfect terra incognita and it is possible, perhaps even more likely, that the Nien-chen-tang-la instead of continuing to Sela-la, takes a more southerly direction and slowly becomes lower and finally disappears near the northern bank of the Tsangpo. A snow-covered group east of the pass is called Kyar, although this name seems to signify a special range which may be parallel to and situated north of the Nien-chen-tang-la. Very likely its northern side drains to the Bara-tsangpo and Kyaring-tso.
The Chang-tang road goes eastwards up to the pass of Sela-la and on its other side turns S.E. The configuration is irregular, for north of the pass the water goes to Ngangtse-tso, S.E. it goes to the Tsangpo and S.W., and even a long way to the west the drainage is also to the Tsangpo. Therefore the road for some distance keeps on the top of hills which constitute a water-parting between the lake and the Tsangpo, although the last and definite and highest water-parting pass is Sela-la with its 5 506 rn height in porphyry, quartzite and mica-schist. Another water-parting threshold a little further west, has only 5 484 m.
The view to the S.E. from the pass does not reach very far as it is hidden by considerable mountains on both sides of the Sele-nang valley. So far as one can see there is, however, a labyrinth of ridges and ranges, and, coming from the north, one is struck by the difference in relief and general morphology between the Chang-tang and the peripheric zone. Such accentuated forms are very rare in Chang-
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