in Europe and North America. 337 
site cliffs between Brunnen and Fliihlen to be an open fracture 
? 
if we take a moderate average slope for each side, say of 65°, 
and produce it below the water, we get a depth, ere the lines 
meet, of between 7000 and 8000 feet—a very improbable 
depth for the original hollow of the lake. But it may be said 
that the fracture has been much widened by degradation, the 
line of the break merely giving a line of weakness, along which 
the surface-drainage might widen the valley. If, however, we 
only take an angle for the sides of the lake giving a moderate 
depth, the necessity for a fracture does not exist, and we recur to 
some process of mere erosion for the scooping of the hollow in 
which the water lies, that process having, I consider, been the 
long-continued grinding of the ice of the great glacier. 
The Lake of Zurich.—The Lake of Zurich runs from N.W. to 
S.E., across the average strike of the Miocene strata, which are 
Mauch disturbed towards its eastern end. It is bounded by high 
8, much scarred by the weather, on which the different Mio- 
cene strata often stand out in successive horizontal steps. The 
Linth Canal and the Wallen See lie in an eastern prolongation 
of this valley, which is still further extended to the valley of the 
Upper Rhine at Sargans. ~The lake is about 25 English miles 
m length, by 24 wide in its broadest part. A great moraine 
ey dams it up at its outflow at Zurich; and a second forms 
the shallow at Rapperswyl, where the lake is crossed by a long 
wooden bridge. The general level of the water is 1341 feet 
above the sea, and only about 639 deep; and the bottom of the 
lake is therefore 702 feet above the sea. The limestone rocks 
at Baden, on the Limat, are 1226 feet above the sea; and the 
e therefore lies in a true rock-basin, though it is probable 
t the old moraine at Zurich accounts for the retention of the 
Water of the lake at its precise level. The long hollow was in 
old times entirely filled by the great glacier which descended 
| the mountains between the Todi and the Trinserhorn, 
through the valley of the Linth, to Raden. 
The Wailen See-—The Wallen See lies in a deep valley, whose 
cag slopes of Secondary rocks rise from 2000 to 3000 feet, and 
in the Leistkamm 4500 feet above the surface of the lake. The 
lake itself is 1891 feet above the sea; and from the great steep- 
hess of its banks it may be inferred that it is exceedingly deep, 
but none of the authorities I have consulted give its soundings. 
large branch from the great Rhine glacier joined that at the 
— of Glarus and Zurich through this wide gorge, and ground 
out the hollow of the Wallen See. 
The Lake of Constance-—The Lake of Constance, the largest 
sheet of water in Switzerland, is about 50 miles in length, by 
ut 15 in breadth at its broadest part. It is entirely sur- 
Tounded by Miocene strata, often considerably diearbek and 
