i68 
SCENERY OF SWITZERLAND. 
The valley of the Rhine below Basle is also a line 
of subsidence, and the two Crystalline regions of the 
Black Forest and the Vosges were once continuous. 
Valleys belong to several different classes, and in 
Switzerland have received special names, such as 
Vais, Combes, Cluses (Clausa, closed), Ruz, Cirques, 
etc., which, however, do not cover all the different 
kinds, and are not always used in the same sense. 
In many cases valleys follow the “strike” or 
direction of the strata, in which case they are termed, 
as first suggested by De Saussure, longitudinal val- 
leys; while in others they cut across the strata and 
are known as transverse or cross valleys, or cluses. 
Longitudinal valleys again, as Escher von der 
Linth first pointed out, are of three distinct kinds. 
Synclinal valleys (see ante, p. 69) occupy the 
depressions of folded strata. Many of the Jura 
valleys belong to this class. They are generally 
broad. 
Anticlinal valleys are those which arise when the 
arch between two synclinals is broken, and the action 
of water being thus facilitated, a valley is formed, as 
for instance the Justithal (Fig. 1 26, vol.11. p. 164), which 
opens on the Lake of Thun. 
In both these classes the strata are the same on 
the two sides of the valley. A third class of longi- 
