The Romance of a Wayside Weed. 69 



miles to the westward of Cape Clear. Beyond that 

 distance the sea-bottom suddenly topples over from a 

 general depth of a hundred fathoms to a depth of a 

 thousand fathoms or more ; which clearly shows that 

 this line, curving round from Shetland to the Spanish 

 shore of the Asturias, must mark an old and long-con- 

 tinued prehistoric land-barrier. In other words, the 

 British Isles are situated on a comparatively shallow 

 submarine bank, which spreads north, south, and east 

 of them, but ends abruptly to the westward by a 

 sudden drop of eight or nine hundred fathoms. If 

 you were now to raise this bank a hundred fathoms in 

 height, you would lift its whole area above the sea- 

 level, save only in the two hollows already noted ; 

 but if you went on raising it for several hundred 

 fathoms more, you would not materially alter the 

 coast-line established by your first elevation. So we 

 can hardly doubt that the hundred-fathom line really 

 represents the old western boundary of Europe 

 towards the Atlantic, because it coincides so nearly in 

 depth with the elevation necessary to unite England 

 and Ireland to one another, and to the Continent. 



Only one element of our problem now remains to 

 be solved ; and that is the question — When did the 

 subsidence take place which turned the dr>' land all 

 round Britain into the beds of the English Channel, 



