THE ORIGIN OP MOUNTAINS. 
49 
CHAPTER II. 
THE ORIGIN OF MOUNTAINS. 
There rolls the deep where grew the tree. 
O earth, what changes hast thou seen! 
There, where the long street roars, hath been 
The stillness of the central sea. 
The hills are shadows, and they flow 
From form to form, and nothing stands; 
They melt like mist, the solid lands, 
Like clouds they shape themselves and go. 
Tennyson. 
The true mountain ranges, that is to say, the 
elevated portions of the Earth’s surface, are the con- 
tinents themselves, on which most mountain chains 
are mere wrinkles; nevertheless when we speak of 
mountains, we mean as a rule those parts of the 
land which stand high relatively to the sea-level. 
Mountain ranges in this sense may be classed 
under two main heads,* viz.: — 
* I say “main” heads, because in certain cases there may 
be other explanations. Yon Richthofen has suggested that the 
Dolomites of the Tyrol were originally coral reefs. 
Scenery of Switzerland. I. 
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