u.] THE PEBBLES IN THE STEEET. 61 



and at last of an Arctic climate ; which last have since 

 retreated either toward their native North, or into cold 

 water at great depths. From Essex across to Wales, 

 from Wales to the asstuary of the Clyde, this fact has 

 been verified again and again. And in the search for 

 these shells, a fresh fact, and a most startling one, was 

 discovered. They are to be found not only in the clay 

 of the lowlands, but at considerable heights up the hills, 

 showing that, at some time or other, these hills have 

 been submerged beneath the sea. 



Let me give one example, which any tourist into 

 Wales may see for himself. Moel Tryfaen is a 

 mountain over Carnarvon. Now perched on the side 

 of that mountain, fourteen hundred feet above the 

 present sea-level, is an ancient sea-beach, five-and- 

 thirty feet thick, lying on great ice-scratched boulders, 

 which again lie on the mountain slates. It was dis- 

 covered by the late Mr. Trimmer, now, alas ! lost to 

 Geology. Out of that beach fifty-seven different 

 species of shells have been taken ; eleven of them are 

 now exclusively Arctic, and not found in our seas; 

 four of them are still common to the Arctic seas and 

 to our own ; and almost all the rest are northern 

 shells. 



Fourteen hundred feet above the present sea : and 

 that, it must be understood, is not the greatest height 

 at which such shells may be found hereafter. For, 

 according to Professor Eamsay, drift of the same kind 

 as that on Moel Tryfaen is found at a height of two 

 thousand three hundred feet. 



Now I ask my readers to use their common sense 

 over this astounding fact which, after all, is only one 

 among hundreds; to let (as Mr. Matthew Arnold 



