1905-6.] Formation of certain Lakes in the Highlands. 107 
On the Formation of certain Lakes in the Highlands. By- 
Dr Leon W. Collet, F. Swiss Geol. S., Assistant to 
Sir John Murray, K.C.B., and Dr T. N. Johnston, 
F.K.S.E. With a Note on Two Rock Basins in the Alps, 
by Dr Leon W. Collet. 
SCOTTISH LAKE SURVEY. 
Under the direction of Sir John Murray, K.C.B., F.R.S., D.Sc., 
LL.D., etc., and Laurence Pullar, F.R.S.E. 
(Read February 19, 1906.) 
When surveying the lochs of the Dee basin in the Highlands, 
we came across three interesting lochs on the formation of which 
we propose to deal in this paper. 
Loch Muick. 
Loch Muick (see fig. 1) lies at the head of Glen Muick, at a 
height of 1310 feet, on the property of His Majesty the King. 
On both sides of the loch the mountain slopes rise precipitously 
from the water’s edge, and reach a height of 2400 feet on the 
south-east and from 2326 to 3352 feet on the north-west. The 
rocks surrounding the lake are granite. 
The loch trends in a N.E. and S.W. direction, and is 2J miles 
in length, the maximum breadth being J mile at the north-eastern 
end. The maximum depth recorded is 256 feet, and the mean 
depth calculated from the volume of water is 111 '69 feet, 
approaching the half of the extreme depth. The ratio of 
maximum depth to the length is 46. That figure shows the 
importance of this basin, as in Loch Morar, the deepest loch in 
the British Islands (1017 feet), that ratio is 61, and the Lake of 
Geneva is 230 times longer than the maximum depth. 
Loch Muick is fed by numerous small burns and streams, the 
largest feeder being the Allt an Dubh-loch coming from the 
Dubh loch, which lies at the very head of the glen, at a height of 
•about 2100 feet. The Glas Allt flows into the loch on the north- 
