214 THE BEAUTIES OF NATURE CHAP. 



one of very moderate elevation, if well placed, 

 such say as the well-known Piz Languard, we 

 see that in many cases they must have once 

 formed a dome, or even a table land, out of 

 which the valleys have been carved. Many 

 mountain chains were originally at least twice 

 as high as they are now, and the highest 

 peaks are those which have suffered least 

 from the wear and tear of time. 



We used to speak of the everlasting hills, 

 and are only beginning to realise the vast 

 and many changes which our earth has un- 

 dergone. 



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. 1 



THE ORIGIN OF MOUNTAINS 



Geography moreover acquires' a new in- 

 terest when we once realise that mountains 



1 Tennyson. 



