VALLEYS. 
185 
our surprise, we find another broad flat expanse. 
This is especially the case with rivers running in a 
transverse valley, that is to say of a valley lying at 
.Fig. 45. — Section showing Weather Terraces. 
right angles to the “strike” or direction of the strata 
(such, for instance, as the Reuss), the water acts 
more effectively than in cross rocks which in many 
cases differ in hardness, and which therefore of 
course cut down the softer strata more rapidly than 
A B C D T 2 
Fig. 46. — Diagram showing the course of a river through hard 
and soft strata. 
the harder ones; each ridge of harder rock will there- 
fore form a dam and give rise to a rapid or cataract. 
In cases such as these each section of the river has 
for a time a “regimen” of its own. 
Suppose for instance a river a b (Fig. 46) running 
