88 LITERARY AND SCIENTIFIC NOTES. 
the older Alps; and the bottom of the first is 1992 feet, and the latter 1043 feet, 
below the sea level. Both of these lie within the bounds of that prodigious 
system of glaciers that descended from the east side of the Pennine Alps and 
the great ranges north and south of the Val Tellina, and shed their moraines 
in the plains of Piedmont and Lombardy. The depths of the lakes correspond 
to the vast size and vertical pressure of the glaciers. The circumstance that 
these lakes are deeper than the level of the sea does not affect the question, for 
we know nothing about the absolute height of the land during the Glacial 
period. 
The Lakes of Thun and Brienz form part of one great hollow, more than 2000 
feet deep in its eastern part, or nearly 300 feet below the level of the sea. They 
lie in the course of the ancient glacier of the Aar, the top of which, as roches 
moutonnées and striations show, rose to the very crests of the mountains between 
Meyringen and the Grimsel. 
The Lake of the Four Cantons is imperfectly estimated at only 884 feet in 
depth ; but here we must also take into account the great height and steep 
inclines of the mountains at its sides. The Lake of Zug, 1311 feet deep, lies in 
the course of the same great glacier, the gathering-grounds of which were the 
slopes that bound the tributaries of the Upper Reuss and the immense amphi- 
theatre of the Urseren Thal, bounded by the Kroutlet, the Sustenhorn, the 
Galenstock, the St. Gothard, and the southern flanks of the Scheerhorn. 
The lesser depths (660 feet) of the Lake of Zurich were hollowed by the 
smaller but still large glacier that descended the valley of the Linth. 
Passing then to an examination of the lakes of the Northern Hemisphere 
generally, Professor Ramsay concludes as follows: 
Furthermore, considering the vast areas over which the phenomena described 
are common in North America and Europe, I believe that this theory of the 
origin of lake-rock-basins is an important point, in addition to previous know- 
ledge, towards the solution of the glacial theory; for I do not see that these 
hollows can in any way be accounted for by the hypothesis that they were 
scooped by floating ice.* An iceberg that could float over the margin of a deep 
hollow would not touch the deeper recesses of the bottom. Iam therefore con- 
strained to return, at least in part, to the theory many years ago strongly advo- 
cated by Agassiz, that, in the period of extremest cold of the Glacial epoch, 
great part of North America, the north of the Continent of Europe, great part 
of Britain, Ireland, and the Western Isles, were covered by sheets of true glacier- 
ice in motion, which moulded the whole surface of the country, and in favorable 
places scooped out depressions that subsequently became lakes. 
This was effected by the great original glaciers (probably connected with the 
origin of the unstratified boulder-clay) referred to in my memoir on the glaciers 
of North Wales, but the magnitude of which I did not then sufficiently estimate. 
#1 donot in any way wish to deny that much of the giaciation of the lower countries 
that came within the limits of the Drift was effected by floating ice on a large scale, which 
must have both polished and striated the rocks along which it ground. I have, with other 
authors, described this in various memoirs. But the two sets of phenomena are distinct. 
