248 
SCENERY OF SWITZERLAND. 
effect as if the surrounding country had risen. The 
result would be to dam up the rivers and fill the 
valleys. For instance, in the Lake of Lucerne the 
bottom of the Bay of Uri is almost fiat; it is evi- 
dently a river valley which has been filled with 
water. 
In fact, speaking generally, the great Swiss lakes 
are drowned river valleys. 
The relative subsidence of the mountains is no 
mere hypothesis. 
There are, as we shall see, strong grounds for 
believing that the country round Geneva has been 
recently raised. 
The old river terraces of the Reuss can still be 
traced in places along the valley near Zug. Now, 
these terraces must have originally sloped from the 
upper part downwards, that is to say, from Zug to- 
wards Mettmenstetten. But at present the slope is 
the other way, i.e. from Mettmenstetten towards Zug. 
From this and other evidence we conclude that in 
the diiection from Lucerne towards Rappersdorf 
there has been an elevation of the land, which has 
dammed up the valley, thus turned parts of the Aa 
and the Reuss into lakes, and, as we shall see, con- 
siderably changed the course of the river. 
Again, Professor Heim has pointed out that there 
