881 



GRADUAL CHANGES OF THE BOTTOM OF THE SEA. 



1. How the gradual change of the Sea-bottom can b- demonstrated 

 — Modifiaitions which the Map of Einopo would suffer by :i 

 gradual sulsidence of Thirty Feet in a century— Paris sul - 

 merged — Europe as it would be were the Level of tliC Sea raised 

 500 feet — Toulouse and Vienna as Seaports. 



We have studied the more sudden shocks to whicli 

 the earth's crust may be subjected. Incessant move- 

 ments of a more gradual kind, which to be demon- 

 strated must be studied during several generations, 

 also influence it, embracing vast regions, and in- 

 fluencing equally the bottom of the sea and the 

 highest mountains. Under the influence of such 

 slow, almost insensible, changes of the earth's crust — 

 countries, at one time flourishing, have disappeared, 

 and others have risen in their stead. 



So long as our study is confined to the sea, or to 

 the interior of continents, we may look in vain ior 

 evidence of such changes ; but if we visit the shores, 

 we may find abundant proof that the ocean is either 

 gradually retreating from, or slowly gaining on, the 

 land. If the sea be apparently retreating, it is a 



