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tourist who seeks for romantic and sublime features. The 
stupendous hills and lofty precipices which almost encircle 
the lake, present one of the wildest and grandest prospects of 
Snowdonia. In the midst of the recesses of these mountains 
is Llyn Idwal, a dark and gloomy lake, which seems the last 
retreat of the wildest and most unmitigated desolation. The 
waters of the Ogwin fall down over a rocky barrier about 
200 feet in height, and along the valley numerous examples 
of the rounded bosses or dome-shaped rocks present them- 
selves. Dr. Buckland, in a paper read before the Geological 
Society of London, December loth, 1841, has given a 
minute detail of the several places in which the rocks pre- 
sented features indicative of glacial action, and which he 
represented in a large map of the valleys of Snowdonia. 
They are especially conspicuous and abundant in the valley 
of Llanberris, near Pont Aber Glasslyn, and Drws y Coed. 
From the extensive observations thus briefly alluded to in 
Dumfriesshire, in Aberdeenshire, in Forfarshire, and Snow- 
donia ; from the concurrent observations made at different 
times by Professor Agassiz and Dr. Buckland, in Westmore- 
land and at Edinburgh ; from the decided opinion of 
Agassiz, Buckland, Lyell, Trevelyan, and others who have 
compared the evidence of supposed glaciers in Great Britain 
with the undoubted evidence of existing glaciers in Switzer- 
land, that they are in both countries precisely the same in 
character and origin ; and from the explanation which is thus 
afforded of many phenomena hitherto unexplained, it is 
obvious that the glacial theory has become a problem of con- 
siderable importance in geology. It is necessarily mixed 
with the consideration of other questions, to enter upon 
which would far exceed the limits of this paper, my object in 
preparing which is not so much to advocate any particular 
theory, as to afford a view of what has been done towards 
establishing it in this country, and also to draw attention to 
