476 _ MR. P, .F, KENDALL ON A SYSTEM OF (Aug. 1902; 
the extra-morainic lakes identified by him. I shall endeavour to 
show that he was correct in the ascription of the Warp-clays of the 
Vale of Pickering to a lacustrine origin as well as the older Warps 
of the Vale of York. On the other hand, I was impelled, some years 
ago,’ to dissent from his identification of the great; Chalky Boulder- 
Clay with lacustrine deposits, an opinion which he shared with, the 
Rev. Edwin Hill. Recent experience has greatly strengthened 
my conviction that that remarkable deposit was laid down by the 
direct agency of land-ice. Mr. Fox-Strangways expressed the 
opinion that the Warp and other alluvium of the Vale of Mien 
was either of lacustrine or estuarine origin. 
It will be seen that, in this country, considerable uncertainty 
prevails regarding the materials which might be accumulated under 
lacustrine conditions; and I may well at this stage define my own 
position upon the question, with specific reference to the accumulations 
in glacier-lakes. 
I have had the opportunity of examining the deposits of two 
well-known lakelets held up by glacier-ice in the Alps, namely, the 
Gorner See and the Marjelen See. The former of these is mainly 
super-glacial in position : it lay in 1894 in the angle formed by the 
confluence of the Grenz and Monte Rosa Glaciers, tributaries of the 
Gorner, and its floor was composed chiefly of ice, though along one 
of its free sides it abutted upon a spur of Monte Rosa, and the right 
lateral moraine and rock-train of the Grenz Glacier descended beneath 
the water. The waters of the lake are prone to rapid lowering of 
level at very irregular intervals, dependent upon the production of the 
crevasses by which they are drawn off. I have at one season seen 
the shallow basin filled almost to the point at which it would flow 
off over the ice, and at another season have found the icy bed almost: 
completely exposed, with large blocks of ice lying stranded near 
the old margin. On both occasions I observed that, besides the 
large masses of rock from the rock-train which were strewn promis- 
cuously about, the deserted bed was covered with a deposit of very 
fine mud, perhaps glacier-meal washed in by a stream flowing 
beside the Grenz Glacier. 
At the time of my visit to the Mirjelen See, the lakelet was 
approaching the condition of repletion which would bring into 
action the new artificial drain, but there was still a large area of 
its floor exposed. This was mainly composed of a bouldery-rubble 
covered with a film of fine mud, but in some hollows I found a 
gritty clay with stones, resembling ordinary moraine-stuff. 
Thus far only extends my personal experience of the deposits of 
modern glacier-lakes ; but Prof. Chamberlin, in his valuable papers 
on the Greenlandic glaciers, and Prof. Tarr, in his description of the 
Cornell Glacier of the Nugsuak Peninsula, have furnished data 
of the greatest value relative to the floor-deposits cf some of the 
countless glacier-dammed lakes of the Arctic regions. Reference 
1 ¢Man & the Glacial Period,’ by G. F. Wright, Internat. Sci. Series, 1892, 
p. 109. 
