CHAPTER IX.. Mechanical Forces At Work in the Disintegration of

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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