338 A. C. Ramsay on the Glacial origin of certain Lakes 
forming great hills towards the S.E., which in a remarkable 
‘manner evince all the signs of long-continued erosion by run- 
ning water, conveying the impression that chiefly by that means 
all the deep valleys of the district have been worn since the 
close of the Miocene epoch. This lake lies 1298 feet above the 
sea; and, its depth being 912 feet, its bottom is only 886 feet 
above the sea. The falls of the Rhine are 1247 feet above the 
Being of greatest thickness where it entered the region of the 
lake, by its enormous weight and grinding power it scooped out, 
in the soft rocks below, the wide hollow now filled with water. 
The Italian Lakes.—If we now turn to the Italian side of t 
Alps, we shall find the same phenomena prevailing in the Lakes 
of Maggiore, Lugano, and Como, the only important lakes I 
have yet had an opportunity of seeing, south of the great chain. 
To each of these the same reasoning applies, modified only m 
detail; and I shall therefore briefly pass them over. 
The most westerly, the Lago Maggiore, lies in a winding val- 
ley, 40 miles long, excavated in gneissic and Jurassic rocks, which 
rise on either side in lofty mountains. The surface of the lake 
is 685 feet above the level of the sea, and near the Borromeam 
Islands it has the enormous depth of 2625 feet; so that its bot- 
tom is 1940 feet lower than the sea-level. It must, therefore, be 
enclosed all round by rocks, unless we suppose the narrow pa 
sage at Arona, near its outlet, to be as deep as its deepest pas 
or that the alluvial deposits of the Ticino and the Po are more 
than 1940 feet deep—an assumption no one is likely to make, 
Of all the Alpine lakes, that of Lugano is the most UT ike 
in form,—in the language of Mr. Desor, stretching its arms ®"” 
a great polyp among the mountains in all directions.” Its pe 
face is 988 feet above the level of the sea, and its depth 515 | he’ 
Its bottom is therefore only 410 feet above the sea-level, and the 
shape of the surrounding ground renders it impossible to believ@ 
that it is not entirely surrounded by rocks. eer 
The Lake of Como, the hollow of which has been scooped i) a 
~ generally in the same set of rocks as the other two lakes, 18 ™ 
4 See memoirs “De la Physionomie des Lacs Suisses” (extrait de la Bid 
conversation with my friend, in 1860, that I first pro 
solution of the question, and to this conversation I 
+ _—— les 
emoir, p. 1 rendu que étaien 
Glaciers qui auraient labouré le sol sur lequel ils s'avancaient,” &e. 
