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the phenomena are which are observable in those countries 
where glaciers now exist, in order that the coincidence of the 
supposed evidence in Great Britain may be considered in 
immediate relation to the evidence afforded under conditions 
which do not admit of doubt. 
It is unnecessary, however, to speak of the glaciers as 
regards the more obvious features which have always ren- 
dered them conspicuous in the sublime scenery of the Alps 
and other mountainous regions. Suffice it to -observe, that 
the enormous masses of frozen snow and ice which till the 
elevated valleys of the Alps extend over about 1,500 square 
miles, varying in length from a few hundred vards to 10 or 15 
miles, and are of various breadth, seldom exceeding 2 miles : 
their thickness in some cases extends to 200 feet, and their 
surface and internal structure are modified by the form and 
temperature of the valleys in which they are situated. Ice- 
land, Greenland, the southwest coast of America, and many 
other parts of the world, abound with glaciers ; but the de- 
tailed phenomena attending them have in no instance been 
so accurately observed and so graphically described as in 
Switzerland. These phenomena are full of interest, and 
during the last two years they have been frequently alluded 
to in scientific publications, and also in others of a more 
popular nature. The splendid work of Agassiz, and espe- 
cially the admirable plates which accompany it, afford a clear 
idea of the principal features of the Swiss glaciers. A brief 
and instructive epitome of this work has been prepared by 
Mr. Maclaren, who accompanied its author in his examination 
of the rocks near Edinburgh. The proceedings of the Geo- 
logical Society of London, and the published reports of the 
British Association, contain many details, and a popular ex- 
planation of the chief phenomena of glaciers is also to be found 
under that head in the Penny Cyclopedia. Without repeating 
what is already so generally diffused and so easily accessible, 
