ELEVATION, on the other hand, increases the activity of all
agencies of weathering, erosion, and transportation, restores the
region to its youth, and inaugurates a new cycle of erosion.
Streams are given a steeper gradient, greater velocity, and
increased energy to carry their loads and wear their beds. They
cut through the alluvium of their flood plains, leaving it on
either bank as successive terraces, and intrench themselves in the
underlying rock. In their older and wider valleys they cut narrow,
steep-walled inner gorges, in which they flow swiftly over rocky
floors, broken here and there by falls and rapids where a harder
layer of rock has been discovered. Winding streams on plains may
thus incise their meanders in solid rock as the plains are
gradually uplifted. Streams which are thus restored to their youth
are said to be REVIVED.

As streams cut deeper and the valley slopes are steepened, the
mantle of waste of the region undergoing elevation is set in more
rapid movement. It is now removed particle by particle faster than
it forms. As the waste mantle thins, weathering attacks the rocks
of the region more energetically until an equilibrium is reached
again; the rocks waste rapidly and their waste is as rapidly
removed.

DISSECTED PENEPLAINS. When a rise of the land brings one cycle to
an end and begins another, the characteristic land forms of each
cycle are found together and the topography of the region is
composite until the second cycle is so far advanced that the land
forms of the first cycle are entirely destroyed. The contrast
between the land surfaces of the later and the earlier cycles is
most striking when the earlier had advanced to age and the later