326 THE BEAUTIES OF NATURE CHAP, 
of its course, nor deposits materials, it is said 
to have acquired its “regimen,” and in such 
a case if the character of the soil remains the 
same, the velocity must also be uniform. The 
enlargement of the bed of a river is not, how- 
ever, in proportion to the increase of its wa- 
ters as 1t approaches the sea. If, therefore, 
the slope did not diminish, the regimen would 
be destroyed, and the river would again com- 
mence to eat out its bed. Hence as rivers 
enlarge, the slope diminishes, and consequently 
every river tends to assume some such “regi- 
men” as that shown in Fig. 46. 
Now, suppose that the fall of the river is 
again Increased, either by a fresh elevation, 
or locally by the removal of a barrier. Then 
once more the river regains its energy. Again 
it cuts into its old bed, deepening the valley, 
and leaving the old plain as a terrace high 
above its new course. In many valleys sev- 
eral such terraces may be seen, one above 
the other. In the case of a river running in a 
transverse valley, that is to say of a valley 
lying at right angles to the “strike” or direc- 
tion of the strata (such, for instance, as the 
