THE REUSS. 
223 
by the Wyttenwasser glacier to the Lake of Luceiidro, 
from there to the Fortunerthal and the Sella See, 
the Val Torta and the Canariathal to the Val Cad- 
limo. 
The summit is of Gneiss belonging to the variety 
known as Fibbia Gneiss. The strata strike parallel 
to the Urserenthal, and at the summit are vertical. 
North of the Hospice the Gneiss dips to the 
south, at the Hospice and on Monte Prosa it is per- 
pendicular, while south of the Hospice the dip is 
northwards, the south wing being, however, smaller 
than that to the north. This arrangement therefore 
gives a typical illustration of the celebrated fan-like 
structure. 
The Protogine of the St. Gotthard closely re- 
sembles both in chemical composition and micro- 
scopical structure that of the Aar massif, and they 
are probably continuous. 
At and surrounding the Pizzo Rotondo is a mass 
of Granite, which appears to be intrusive. It is 
evidently less ancient than the Gneiss, since it con- 
tains angular masses of that rock. 
From the St. Gotthard radiate six important 
rivers; the Rhone to the W., the Rhine to the E., 
the Reuss to the N.E., the Aar to the N.VV., the 
Ticino to the S.E., and the Toce to the S.W., and 
