CHARACTERISTICS AND DISTRIBUTION OF LAKES 537 
"On Explorations in Central Asia, 1906-1908,"' in the Geographical 
Journal (vol. xxxiv. p. 26, 1909), says that at the time of his visit 
the new lakes found by Sven Hedin in the Lob Desert had almost 
disappeared. Sven Hedin, in the discussion on the same paper (p. 270), 
observes that whether this denotes that the lakes are in a period of 
shifting, or that in general the volume of water carried down by the 
Tarim has been diminished in recent years, can only be determined by 
comparison of the maps and measurements of the river. 
From all this it may be fairly inferred that, owing to the uniform 
level of the region, the sluggish flow of the Tarim, its tending to 
divide and reunite, conjoined with the violence of the winds (mostly 
from the east and north-east) and the rapid and dense growth of the 
reed-beds in the shallow marshes, the drainage waters of the Tarim 
basin gather in greater volume now in one depression and now in 
another. This view derives support from the extreme shallowness of 
the lakes in both Sven Hedin's northern Lob-Nor and Prejevalsky's 
southern Lob-Nor. 
Ellsworth Huntington sums up the history of Lob Nor thus ^ : — 
" We have first a comparatively large lake, said to measure 75 miles 
each way, in spite of the fact that the populous towns of Lulan and 
of more remote regions diverted much more water than now. Next, 
during the early centuries of the Christian era, there is a decrease in 
the recorded size of the lake, even though the towns of Lulan were 
being abandoned and their water was ]jeing set free to reinforce the 
lake. Then, in the Middle Ages, there was an expansion of the lake, 
which cannot have been due to diminished use of the rivers for irrig-a- 
tion, for the population of the Lop-Nor basin at that time was 
greater than now, though not equal to that of the flourishing 
Buddhist times, a thousand or more years earlier. Finally, during the 
last few hundred years there has been a decrease both in the size of 
the lake and in the population about it.'' This theory, Huntington 
says, seems to fit the facts, and all the facts are explicable on the 
theory of a secular change of climate from moister to drier conditions, 
with a rapid intensification in the early part of the Christian era, 
and a slight reversal in the Middle Ages. Hedin,'- on the other 
hand, who utterly scouts the idea of any change of climate during 
historic times, recognises that during certain periods Lob-Nor has 
been distinctly larger than it is, even during times of unusually high 
water, at the present day. He explains this on the assumption that 
during these periods the number of marginal lakes and swamps on the 
Tarim River was less than now. The objection offered to this is that, 
when a river has reached the mature stage of the Tarim, the average 
1 Bull. Amer. Geogr. Soc, vol, xxxix. jd. 146, 1907. 
2 Cited by Huntington, oj). cit., p. 142. 
