VALLEYS, PLAINS, AND LOWLANDS 
239 
of rock, with precipices and overhanging crags, 
prove one of two things: Hither the rock is 
very hard or the exposure is very new. The 
wear of the elements tends to round, smooth, 
and flatten down all such sharp projections. 
In the older valleys of the world, such as those 
of the Alleghanies, the sides are sloping, the 
basins rounded, and the lines against the sky 
show only the smoothest curves. Usually a 
small river or brook winds its way down the 
larger valleys, cutting out the soft deposits of 
earth and forming banks or cliffs on either side, 
where vines clamber and stunted pines cling in 
the fissures of the rocks, and small trickling 
streams drip from under thick carpetings of 
moss. It is usually a noisy, swift-running 
stream, dashing its way seaward over shelves of 
stone and gravel, winding in and out of deep 
pools, and swirling around sharp bends in|, 
eddies and circles. Its tributaries are the little 
cold-water rivulets that come down the side 
guiches, springing over ledges and bubbling 
into basins—streams where the young trout 
splash in their leaps up the falls, and where 
the stealthy-footed inhabitants of the wood 
come to drink. 
The brook, the river, the valley, and the 
Sloping 
sides and 
smooth 
curves. 
The brook 
again. 
