260 THE BEAUTIES OF NATURE CHAP, 
approach so near that there is not even room 
for the river and the road: in that case 
Nature claims the supremacy, and the road 
has to be carried in a cutting, or perhaps in 
a tunnel through the rock. In other cases 
Nature is not at one with herself. - In many 
Fig. 25. — Section of a river valley. The dotted line shows a slope or 
talus of debris. 
places the debris from the rocks above would 
reach right across the valley and dam up the 
stream. Then arises a struggle between 
rock and river, but the river is always vic- 
torious in the end; even if dammed back for 
a while, it concentrates its forces, rises up 
the rampart of rock, rushes over trium- 
phantly, resumes its original course, and 
gradually carries the enemy away. 
