Chapter IX

Mechanical forces at work in the disintegration of
rocks--Rains--Landslips--Effects of frosts--Glaciers and
icebergs--Abrading power of rivers--Suggested volume on the
geology of rivers--Some of its probable contents--Scene
in a woody ravine--First idea of the origin of the ravine
one of primeval cataclysms--Proved to be incorrect--Love
of the marvellous long the bane of geology--More careful
examination shows the operations of Nature to be singularly
uniform and gradual--The doctrine of slow and gradual change
not less poetic than that of sudden paroxysms--The origin
of the ravine may be sought among some of the quieter
processes of Nature--Features of the ravine Lessons of the
waterfall--Course of the stream through level ground--True
history of the ravine--Waves and currents--What becomes of the
waste of the land--The Rhone and the Leman Lake--Deltas on the
sea-margin--Reproductive effects of currents and waves--Usual
belief in the stability of the land and the mutability of the
ocean--The reverse true--Continual interchange of land and
sea part of the economy of Nature--The continuance of such a
condition of things in future ages rendered probable by its
continuance during the past,

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