504 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. Atall 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, however, 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 giacier 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- 
tinuity 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 
