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Geological Society. 



gravel, containing blocks of different size heaped together without 

 order, and containing no organic remains but bones of Mammalia 

 and insignificant fragments of shells, he is of opinion was also not 

 produced by true glaciers, although intimately connected with the 

 phenomena of ice. The polished and striated surfaces of the blocks 

 leaves no doubt on M. Agassiz's mind that these masses have been 

 acted upon by ice in the same manner as the blocks which are ob- 

 served under existing glaciers, and which are more or less re- 

 arranged by water derived from the melting of the glaciers. 



Similar detritus fills the bottom of all the Alpine valleys, as that 

 of the Rhone to its junction with the Lake of Geneva, and the valley 

 of Chamonix : it is found between the Hospice du Grunsel and the 

 borders of the lower glacier of the Aar ; thence to the neighbourhood 

 of Goutharen in the Oberhasli, at Inn Grund ; also in the plains of 

 Meyringen, Interlasken, and between Thun and Berne. At all these 

 localities the blocks were left, when the glaciers extended to them. 



With respect to the valley of the Aar, M. Agassiz says it is easy 

 to prove that the rounded pebbles spread along its whole course 

 were not transported to their present position by that river, because 

 between the glacier from which it issues and Berne the flowing of 

 the stream is interrupted by the barrier of Kirchet, the Lake of 

 Brientz, and the Lake of Thun ; and because between these lakes 

 its velocity is so small, that it transports only mud and very fine 

 gravel, and that the pebbles over which the river flows below Thun 

 do not issue from the lake. Supposing that the volume of the Aar 

 was formerly greater, why, asks M. Agassiz, are not the lakes of 

 Brientz and Thun filled in the same manner as the plains of Mey- 

 ringen and the bottom of the valley which separates the two lakes ? 

 All difficulties, hov/ever, he is of opinion, vanish, if the pebbles be 

 considered the detritus of retreating glaciers, and that the hollows 

 occupied by the lakes of Brientz and Thun were filled with glaciers. 



The existence of a glacier in this valley is not imagined by the 

 author to explain the origin of the detritus, as its having existed is 

 proved by the polish on the rocks in situ from the glacier of the Aar 

 to Meyringen, a distance of twenty English miles, and even on the 

 shores of the Lake of Thun. Similar phenomena have been noticed 

 by M. Agassiz in Scotland, in the valleys of Loch Awe and Loch 

 Leven, near Ballachalish, and in England in the neighbourhood of 

 Kendal. 



The author then proceeds to describe the moraines of Switzerland, 

 or the accumulations of blocks and pebbles deposited longitudinally 

 on the borders, and transversely in front, of glaciers, and success- 

 ively abandoned by them in their retreat. These moraines differ 

 from glacier-detritus remodelled or spread out by water, in being 

 disposed in ridges with a double ta'us, one flank of which is presented 

 to the glacier, and the other to the side of the valley ; and their con- 

 tinir.ty and parallelism at the same height easily distinguish them 

 from the blocks disposed along the bottoms of valleys by currents. 

 They occur on the flanks of all glaciers, but they have been also ob- 

 served by M. Agassiz where no glaciers exist, as in the valleys of 



