INTRODUCTION. XI 



any part of the ocean, from one pole to another, has 

 been exempt from its operations. 



The level of the earth everywhere is continually 

 changing. That of the sea is, on the contrary, fixed ; 

 and although we are accustomed to speak of its ad- 

 vancing and retiring, the only motion it has of this 

 kind is occasioned by the tides, and is never permanent. 

 Sea and earth may be compared to two sisters, the elder 

 one staid and sedate, the younger giddy and fickle. 

 The solidity of the earth and capriciousness of the sea 

 are poetical terms, but incorrect in a geological point of 

 view. Poetry and Geology have seldom much in com- 

 mon. It is a striking fact, that every part of the earth's 

 surface which is now habitable or dry, has at more 

 periods than one formed the bed of the sea : 



" Each changing place with that which goes before, 

 In sequent toil all forwards do contend." 



There is not an individual particle of this crust but what 

 has been often shifted and transformed ; and the phases 

 of a kaleidoscope are not more varied than the configu- 

 rations which have resulted from such changes since 

 time commenced its task of revolution. The inevitable 

 recurrence of similar fluctuations will assuredly make 

 our rich and favoured isle again the seat of watery- 

 wealth although it may not be laid waste by a deluge 

 such as Horace describes, 



" Omne quum Proteus pecus egit altos 



Visere montes, 



Piscium et summa genus haesit ulmo, 

 Nota quse sedes fuerat columbis, 

 Et superjecto pavidae natarunt 



.ZEquore damae." 



Not long afterwards Manilius (who was a better geo- 

 logist than Horace) showed the reverse of the medal : 



