SCENERY OF SWITZERLAND. 
218 
The Ghschenenthal differs from the other lateral 
valleys, as already mentioned, in opening to the Reuss 
Valley on a level. 
Now why does this one valley differ in this re- 
spect from all the others? The answer is that it is 
a valley of a different character from the rest. They 
are due to lateral torrents. The Goschenenthal is a 
tectonic longitudinal valley, which is continued across 
the Reussthal, on the eastern side forming the Rien- 
thal. 
Prof. Heim has made an interesting calculation as 
to the annual denudation in the Reuss Valley. He 
estimates the yearly rainfall in the area drained by 
that river at 1,070,000,000 cubic metres, and the 
outflow of the river into the Lake of Lucerne at 
7 50)000)000. The daily discharge of sand he cal- 
culates as about 150,000 cubic metres, to which he 
adds a quarter for finely divided matter. This would 
be equal to about 1000 waggon loads a day. Ac- 
cording to his calculation then the average annual 
removal from each square kilometer of surface would 
be 242 cubic metres. 
From the amount of material removed he cal- 
culates the ages of the terraces as follows:— 
