238 GEOLOGY OF THE ISLE OF WIGHT. 



above the sea is from 100 to 400 feet. It is pro- 

 tected on the north by the escarpment of the 

 southern chain of hills, which forms a line 

 of vertical cliffs, from 200 to 400 feet high, 

 and extends from St. Catherine's to Shanklin 

 Down. 



There is perhaps no tract of such limited ex- 

 tent, that affords so remarkable an instance of 

 the modification of climate induced by geologi- 

 cal structure and physical configuration, as the 

 Undercliff. Completely sheltered on the north by 

 the range of chalk cliffs — elevated above the in- 

 fluence of the mists and fogs of the sea-shore — 

 possessing a soil composed of the detritus of chalk 

 and sandstone, which rapidly absorbs and carries 

 off superfluous moisture, yet supports a luxuriant 

 vegetation — with an undulated and varied surface 

 enjoying throughout its whole extent a southern 

 aspect — and fanned only by breezes which invigo- 

 rate but do not chill — this fairy region well merits 

 the high encomium of the medical philosopher. It 

 is indeed, what Sir James Clark, in his invaluable 

 work on Climate, has described it to be — " a lofty 

 natural terrace backed by a mountainous wall on 

 the north, and open on the south to the full in- 

 fluence of the sun from his rising to his going 

 down, during that season when his influence is 



