GEOLOGY 
add anything here to what Sir Andrew Ramsay has said on the subject 
in general, or to what the late Rev. J. Clifton Ward has written in regard 
to the glacial origin of the Cumberland and Westmorland lakes in 
particular.’ All of them are simply old river valleys deepened and 
widened by the long-continued erosive action of glacier ice. The 
slow and persistent grinding to which this erosion is due produced 
most effect at the points where the motion of the bottom layers was at 
its greatest and where the pressure was at its maximum. It may be as 
well to bear in mind in this connection the important fact that ice 
expands with a rise of temperature, and contracts with a fall, to a greater 
extent than any other solid known. A thick mass of ice under cold 
atmospheric conditions is warmer below in proportion to its depth, be- 
cause it is not so much chilled by surface cold, and, at the same time, its 
lower parts intercept much of the heat radiated outward from the earth. 
That is to say, the base of the ice is warmer than its upper surface ; and, 
being warmer, expands more, and therefore slowly creeps outward in the 
direction of least resistance, which usually follows a parabolic curve 
upwards from the sole of the ice and outwards from its source. As the 
weight of a column of ice one thousand feet in thickness on a base of 
a square foot is more than twenty-five tons, one can readily see that this 
steady upward and outward creep of the bottom layers, charged as they 
are with grit and rock fragments, must give rise in course of long periods 
to erosive effects of considerable importance. The fact that ice is nearly 
transparent to all the light rays and to most of the heat rays from the sun, 
while the foreign matter within the ice is not, helps still further to raise 
the temperature of the lower parts of the ice, and, by making them 
expand most, propels them forward over the rocks. 
It may be mentioned here that several other lakes than those now 
existing as such formerly had a place in Cumberland and Westmorland. 
There was a large one, now occupied by alluvium, between Ullswater 
and St. Ninian’s Church on the Eamont. The lip of the rock basin 
which contained that lake has been notched through by the river, and 
now forms the picturesque gorge of Udford Crags adjoining Edenhall. 
Another lake of larger size, also now silted up, once extended along the 
Eden from Appleby to Eden Lacy. Here, again, the beautiful rocky 
gorge and the rapids on the Eden at Eden Lacy are simply vestiges of 
the lip of the rock basin that formerly held in the water of the Eden 
and formed the lake in question, until the river notched the gorge deeper 
and let the water out. There was asimilar lake, also with a gorge below 
it, at Kirkoswald. East of Keswick there was one at Threlkeld, of 
which the former lip is represented by the picturesque gorge on the 
Greta between that place and Keswick. Indeed it would be easy to 
multiply examples, for they are to be found here and there all over the 
county. All are simply enlargements of old river valleys, effected by 
glacial erosion. All have been true rock basins, which have once held 
lakes, and have been converted into meadow land by the double process 
1 Quart. Fourn. Geol. Soc., xxx. p. 96. 
55 
