*74 
SCENERY OF SWITZERLAND. 
which may be termed fault- valleys. They are, how- 
ever, comparatively rare. 
One and the same river may be of a very dif- 
ferent character in different parts of its course. It 
may run at one place in a longitudinal, at another 
in a transverse valley. The Rhone for instance oc- 
cupies a transverse valley from the glacier nearly to 
Oberwald, a longitudinal valley from Oberwald to 
Martigny, and a cross valley from Martigny to the 
lake. 
If we look at an ordinary map of Switzerland, 
we can at first sight trace but little connection be- 
tween the river courses and the mountain chains. 
If, however, the map is coloured geologically, we see 
at once that the strata run approximately from S.W. 
to N.E. and that the rivers fall into two groups 
running either in the same line or in one at right 
angles to it. 
The central mountains are mainly composed of 
Gneiss, Granite, and Crystalline Schists; the line of 
junction between these rocks and the Secondary and 
Tertiary strata on the north, runs, speaking roughly, 
from I Iyeres to Grenoble, and then by Albertville, 
Sion, Chur, Innsbruck, Radstadt, and Hieflau, to- 
wards Vienna. This line is followed (in some parts 
of their course) by the Isere, the Rhone, the Reuss, 
