326 General Notes. [ May, 
my first exhibition of it, being an extra sheet of the May number 
of the American Fournal of Science and Arts—E, D. Cope, Phila- 
delphia, March 20, 1878. 
THE ORIGIN oF Laxes.—Prof. Ramsay, F.R.S., Director-Gen- 
eral of the Geological Survey, gave the Monday evening lecture 
at the London Institution on “The Great Ice Age.” He com- 
menced with a description of a typical Swiss glacier, drawing 
special attention to that which is commonly called the perpetual 
snow line, here some 8,500 feet above the sea level, which is 
called perpetual rather by courtesy than as being an absolute fact. 
While it is the snow which furnishes the mass of the glacier, the 
fragments of rock carried down originate in this way: There are 
some steep slopes which are not covered with snow, and are 
exposed to the heat of the sun. The alternating heat during the 
day and the cold of the night cause disintegration, and masses of 
the rocks are broken off, which not only form the heap of rubbish 
called moraines, but some of which, falling through the crevasses, 
form the “ graving tools ” which score the mass of rock beneath 
into grooves. If we look further afield, we find glaciers in the 
Himalayahs, in Greenland, and in Victoria Land which make those 
of Switzerland appear quite insignificant. In Victoria Land the 
sheets of ice which float off are of enormous thickness, and indi- 
cate through what a severe glacial period the Southern Hemis- 
phere is passing. The chief signs by which the former existence 
of glaciers in places where they no longer flow can be traced, are 
the old moraines and the scratchings on the rocks. Taking these 
as guides, the eye of a trained glacialist can detect with certainty 
the traces of long-departed glaciers in many parts of the world. 
The well-known examples in Wales were first mentioned, and 
then in succession those of Scotland and North England were 
described. There is evidence in Scotland that in former times 
time was smothered in glacier ice. The glaciation of Anglesea 
was the result of a different system from the glaciers of Wales, 
as is proved by the fact that the striations of the rocks lie in dif 
ferent directions.. The Scandinavian mountain chain has been 
unmistakably moulded by glacier action, and there are abundant 
evidences that North America has been intensely glaciated. 
These facts had been noticed by many observers, but there was 4 
point in connection with this which Prof. Ramsay said he claime 
as his own idea, and that was with regard to the origin of lake 
basins. His belief is that in all cases they have originale 1 
from glaciers—that is, that the basins have been scooped ou 
_ by glaciers. He pointed in confirmation of his position to cases 
ie many parts of the world where there are lake basins near 
Sig abi 
