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cussion, and which are independent of the composition of the stone ; 
moreover wherever the moveable materials which are pressed by the 
ice on rocks 7m situ are the hardest, there occur, independent of the 
polish, strize more or less parallel, and in the general direction of 
the movement of the glaciers. Thus in the neighbourhood of gla- 
ciers are found those rounded bosses which Saussure distinguishes 
by the name of ‘‘ roches moutonnés.’’ These phenomena M. Agas- 
siz has traced under the glacier of the Aar, and he has observed 
them in the valley of the Rhone, and of Chamounix; also in Scot- 
land, on the banks of Loch Awe and Loch Leven; and he says they 
are very remarkable in the environs of Kendal. 
The most striking points in the distribution of the striz, are their 
diverging at the outlets of the valleys, and their being oblique, and 
never horizontal on the flanks, which they would be, were they due 
to the agency of water, or floating masses of ice. The cause of this 
obliquity the author assigns to the upward expansion of the ice, and 
the descending motion of the glacier. 
The most remarkable striated rocks in the Alps are near Handeck, 
and near the cascade of Pissevache; and the best examples M. 
Agassiz has seen in Scotland, are those of Ballahulish, and in Ireland 
those of Virginia. 
If the analogy of the facts which he has observed in Scotland, 
Ireland, and the north of England, with those in Switzerland, be © 
correct, then it must be admitted, M. Agassiz says, that not only 
glaciers once existed in the British Islands, but that large sheets 
(nappes) of ice covered all the surface. 
The author then details the proofs that glaciers did not descend 
from the mountain summits into the plains, but are the remaining 
portions of the sheets of ice which at one time covered theflat country. 
It is evident, he says, if the glaciers descended from high mountains, 
and extended forward into the plains, the largest moraines ought to 
be the most distant, and to be formed of the most rounded masses ; 
whereas the actual condition of the detrital accumulations is the re- 
yerse, the distant materials being widely spread, and true moraines 
being found only in valleys connected with great chains of lofty 
mountains. 
It must then be admitted, the author argues, that great sheets of 
ice, resembling those now existing in Greenland, once covered all 
the countries in which unstratified gravel is found; that this gravel 
was in general produced by the trituration of the sheets of ice upon 
the subjacent surface ; that moraines, as before stated, are the effects 
of the retreat of glaciers; that the angular blocks found on the sur- 
face of the rounded materials were left in their present position at 
the melting of the ice; and that the disappearance of great bodies of 
ice produced enormous debacles and considerable currents, by which 
masses of ice were set afloat, and conveyed, in diverging directions, 
the blocks with which they were charged. He believes that the 
Norwegian blocks found on the coast of England have been correctly 
assigned by Mr. Lyell to a similar origin. 
Another class of phenomena connected with glaciers, is the form- 
