EASTWARDS THROUGH THE LATITUDINAL VALLEY. 37
only 3 m. higher than now. It may easily have had an effluent to the lake in the west, or, if it has been in connection with it, to some now dried up depression farther west. It partakes, of course, in the general desiccation of all Tibetan lakes.
The panorama 24A and 24B, Tab. 5, taken from Camp IX, again gives a quite different view from the previous ones, and introduces two new characteristic features in the Tibetan plateau-landscape. One is the Lake of Aksai-chin which dominates half the foreground with its brilliant blue sheet of water. The other is the opening of the great latitudinal valley. Between a few degrees north of west and N. 59° W., there are no mountains visible, only the gradual slope or very flattened scree at the northern foot of the limestone mountains we had passed along from Camp VIII. Between N. 89° E. and S. 86° E. one only suspects, because of a low blue rim above the horizon, that mountains, or perhaps only a flat threshold will be met with somewhere very far to the east. The mountains north and south of the lake appear in all their details. Of the great Kwen-lun Range nearly nothing is visible as the standpoint is too low.
On September i itl2 we continue E. S. E. a distance of 25 km. The ground is nearly level, for Camp X has a height of 4,894, or only 20 m. below Camp IX.
Leaving the small swamps around the spring of Camp IX, we march along the edge of an old beach-line of the lake. For a short distance the ground is pierced by narrow furrows about one foot deep, which rather seemed to have been formed in connection with the desiccation than by erosion. The soil consists of the same kind of clay as we had found on the shore of the lake, which indicates that we are riding a few kilometers on old lake bed. The clay is here very soft, and the ponies sink 1 dm. or more in it. The tract is absolutely barren and salt. In a small depression some salt water stood. Other depressions were dry, and dry watercourses were directed to them. The ground seems to be like that the whole way to the foot of the scree at the base of the northern mountains; its colour in that direction is generally greyish, sometimes turning into dirty blue or yellow. All this proves that the lake in bygone time must have been much bigger than nowadays.
To the right or south a considerable transverse valley is opening. The mountains to the north were mostly hidden by clouds and hail. Sometimes slightly convex areas covered with gravel, 1 cm. in diameter, are crossed. Belts of clay are still passed, and we cross four beach-lines, mostly of hard, fine gravel, and of the same kind as the one nearest the lake shore. After having left all these old remains from the earlier extension of the lake, we enter a plain of hard sand and gravel with sparse yapkak plants. Through a broad valley between comparatively low mountains to the south, a considerable snow-covered group is seen. Other parts of it appear later on, indicating a range south of and parallel with our latitudinal valley. The distance to this range seems to be about I o km. Its colour is light
IIIFカラー高解像度
