428 Probable influence of 



glacial theory. Within that period, the structure of ice, its 

 mode of formation and progression in those mighty masses 

 which hang upon the mountain sides at the limit of per- 

 petual snow, its abrading and transporting influence, have 

 attracted profound attention. A distinguished philosopher of 

 Edinburgh, Prof. Forbes, ^vho expresses the importance which 

 has been attributed to this subject, remarks, that " the glacial 

 theory, whether it regards the present or past history of those 

 mighty and resistless vehicles of transport and degradation, 

 yields to no other physical speculation of the present day in 

 grandeur, importance, and interest." Since our last meeting, 

 several of the most profound philosophers and geologists of 

 Europe have encamped for weeks upon the glaciers of the 

 Alps, to explore their various phenomena, and have filled 

 the scientific journals with their acute, though, unfortunately, 

 acrimonious discussions upon the glaciers. 



The proper glacial theory, as originally proposed, which 

 attributes tlie abrading and and polishing of rocks, the trans- 

 portation of erratic blocks, and the formation of some of the 

 peculiar accumulations or ridges of gravel and bowlders which 

 occur in our drift, to the agency of mountain glaciers, has 

 lost the favor which it originally received. A modification 

 of this theory has been suggested by Mr. Murchison, the 

 President of the London Geological Society, in his late 

 annual address, whose views are nearly the same, if I mistake 

 not, as those advocated by geologists in our own country. 

 He supposes that icefloes, and their detritus, might be set in 

 motion by the elevation of the Scandinavian continent, and 

 the consequent breaking up of the (^reat glaciers on the 

 northern shores of a sea which then covered all the flat re- 

 gions of Russia; that t!ie bottoms of these icebergs, extend- 

 ing to a great depth, must have, every here and tliere, stranded 

 upon the highest and most uneven points of the bottom of 

 the sea, and that the lower surface of the iceberg, like the 

 lower surface of a glacier, would score and grate along the 

 rock. 



I may say, in short, that ths eflfects which have been at- 



