17(3 
liecords of the. Geological Survey of India. 
[vOL. XI. 
All the rocks of this basin, whether shales or limestones, are singularly 
unsuited to the retention of the minor glacial marks; and if glaciation did take 
place, it may be from this cause that no such traces are now found. 
From an inspection of the large scale map, it will be at once apparent that 
the head of the valley has very much the form of a ‘ cirque, ’ as defined by 
Mr. Helland,’ who argues with considerable force that the cirques of Norway 
and Greenland are due to glaciers. Mr. Bonney,^ on the other hand, describes 
Alpine cirques, which he believes to be formed by streamlets pouring down the 
sides. It has often been remarked how some forms of our Indian alluvia 
under the operation of heavy rainfalls exhibit in miniature many of the forms 
of denudation and erosion. Among these forms, cirques and cirque valleys are 
not unfrequently met with. Invariably, they are due not to denuding action 
from above, but to subterranean springs or streams. To a similar cause may, 
I think, be attributed cirque-like valleys in rocks formed of loose shales and, 
to some extent, even those where the rocks are limestones. 
The accompanying section of the bed of the lake indicates a state of things 
very different from what might have perhaps been anticipated, but, however the 
lake has been formed, explanations to account for the peculiarity about to be 
described can be suggested. 
The soundings from which this section has been plotted have been taken 
from the Revenue Survey map on the scale of ten inches to a mile. In some 
cases the exact character of the bottom is given, but not in all. A knowledge of 
this character is, no doubt, a very great desideratum for the discussion of this 
question. It would be especially desirable to know the nature of the bottom all 
across the lake transversely to this line at the point where the shallowest sound¬ 
ing occurs. As represented in the section, the lake consists of two basins, witli 
the maximum depth nearly centrically situated in each case. They are separated 
by what appears to be a barrier. If it really be so, then it would lend consider¬ 
able support to the glacial hypothesis. Indeed, if consisting of rock in situ, it 
would fairly prove the existence of a true rock basin, thus fm-nishing a strong 
argument in favor of the glacial origin. Supposing it to be so, the twin basins 
might be readily explained by the hypothesis that they had been successively 
excavated by the retreating end of a glacier. Unfortunately the case is not 
susceptible of so simple an explanation, as the shallow sounding may be caused, 
not by a barrier, but by a mere hummock, which, if (as is possible, so far as is 
certainly known at present) occurring isolated by deep channels from the margins 
of the lake, would be on the other hand a strong argument against the glacial 
origin, as such an obstruction must assuredly have been swept away by a glacier 
capable of scooping out the deeper hollows. Still another view of the nature 
of the barrier or hummock, be it which it may, is possible. It may be that it is 
not really formed of rock in situ, but is merely the remnant of an ancient 
landslip. 
‘ “ Cirques are large spaces excavated from the solid rock, bounded on three sides by an 
almost semicylindi'ical steep mountain wall, and with a tolerably flat floor.”—Quar. Jour., Geol. 
Soc., Vol. XXXIII, p. 161. 
^ In making these remarks, I labour under the disadvantage of being in camp, away from 
opportunities of reference to Mr. Bonney’s papers. 
