SOUNDINGS IN LAKE LIGHTEN. 47
however, not the decisive factor, for on Spitzbergen for instance, large glaciers are formed on much shorter slopes. If the enormous quantities of débris that have filled up and levelled the great latitudinal valley suddenly disappeared, the névés and firn troughs on the range in question would of course, still be insufficient to give rise to glaciers worth mentioning. The decisive factor is that the precipitation is not sufficient for feeding glaciers, and the evaporation is enormous in the dry air.
Between S. 9° W. and S. 29° W. some of the lower mountains are seen which are situated to the north of the great southern range. The little gap S. 2 9° W. is the slow ascent to the transverse threshold. The low hills to the right of it are ramifications from the northern side, altogether hiding the open valley in the direction of AI sai-chin. To the N. W., north and N. E. no high mountains are visible, except to the N. 32° W. where a great mass is showing its snow-covered head. To the N. E., however, a gigantic cupola-shaped mass with eternal snow was situated, though it was hidden by clouds when I sketched. In the foreground, looking south, extends the blue sheet of the lake. Nothing is to be seen of the narrow plain at its southern shore. One may nevertheless suspect the existence of such a shore-plain, as there is a gap between the base of the recent screes and the shore-line.
On the evening of Sepal/her 191/i, a regular W. S. W. storm blew over the highlands, and it was interesting to see how real clouds of sand and dust were carried away out across the lake. Theoretically one would expect that the western half of an oblong lake which fills out nearly the whole breadth of a latitudinal valley, and is exposed to the prevailing S. W. and W. S. W. wind, would be shallower than the eastern half of the same lake. This ought to be the case in a still higher deli gree when a nearly 200 m. high threshold is situated a short distance west of the lake. For on the lee side of this threshold the wind would lose a good deal of its force and the solid material carried by it fall down. But this seems not to be the case. At Camp XV the wind was very strong and the clouds of sand and dust were blown far away over the lake. A line of soundings, being nearly 9 km. in length, which I took between Camps XV and X VI, also proved that the lake was surprisingly deep in its N. W. part. The 1 m. isobathic line lay, it is true, at about 2 50 m. from the shore. Some 500 m. out we measured 6.6, after which we soon had 44 m., and then 45.2, and 48.5 m. A depth of 34.5 m. was found at only zoo m. from the shore near Camp XVI. At about 5o m. from the shore we had 3.8 m. Therefore, the 1 m. line is much farther out from the western shore than from the northern, which, in some degree, may depend on the wind-blown sand. The northern shore consisted of gravel, the last visible part of the scree from the northern mountains, V; which may be supposed to continue out into the lake.
At the western shore the water was as clear as crystal , and the bottom here consisted of fine gravel and sand with ripplemarks. No animals or plants were seen.
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