THE WATERS TO THE NORTH OF THE KARA-KOSCHUN. 133
is transported successively from i to 2, 3, 4, 5, etc. After five storms, or rather five fractional portions of the same storm,* the dust and sand, which fall after the first of these upon the area 1, will come to rest finally upon the area 5. After the second storm unit (i. e. that part of a storm which is represented by the length of the rectangles in question, and which for the sake of brevity I have designated »storm») a fresh layer of sand and dust, brought from the north-east, is spread out over both areas 1 and i a ; the former layer then lies upon 2, while upon 2 a there is practically no layer of similar matter, for the wind section which blows across the lake emerges on its leeward side relatively clear, or at all events it has got rid of the heavier material, and has discharged all the drift-sand it carried with it.
Fig. 85. EFFECT OF THE DRIFT-SAND UPON THE KARA-KOSCHUN.
Farther towards the south-west, say on 5 a, the balance may be considered to be practically restored again. That is to say, while the solid matter from I continues to be shifted onwards stage by stage, transported farther and farther towards the south-west by each fresh storm, the matter which each successive storm drops upon I a remains there, staying where it fell. So that after five storms the layer over 1 a is five times as thick as the layer which fell originally upon 1. From this train of reasoning it is very evident, that the depression I a, which is now filled with water, must eventually be entirely filled up with solid matter, and that the accomplishment of this result is merely a question of time. In addition to this, there are yet other agencies which accelerate the levelling up of the depression ; these I shall advert to lower down.
* A wind like that which blew at r p.m. on 7th April travels 14 m. in the second, 84o m. in the minute, 5o km in the hour, and 1 210 km. in the 24 hours; that is in this last period it covers a distance equal to that between Kum-tschapghan and Kaschgar. But where the usual Lop storms come from, and how far they go, I cannot determine. In the Lop region at all events they appear to attain their greatest intensity and constancy in the relatively narrow »gateway» between the Kuruktagh and the Astin-tagh — the »gateway» that is which connects East Turkestan with the deserts of Eastern Asia.
IIIFカラー高解像度
