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14 



INTRODUCTORY ESSAY. 



dred feet above the level of the sea; and forming 

 one of the many indubitable proofs, some found at 

 very high elevations, that the dry land of our pre- 

 sent habitable world has once been under the surface 

 of the ocean — that the land has been elevated, or 

 the waters have subsided. Although it is interest- 

 ing to inquire how far one, or both of these causes 

 may have operated in far remote ages, it is en- 

 tirely foreign to my present object to enter into 

 the wide field of inquiry, to which such phenomena 

 would lead. 1 would rather call the attention of 

 Geologists to the following points. 



The first is the high elevation, which the coralline 

 aggregate attains in Barbados; and the fact, that in 

 many situations precipitous walls are exposed of 

 considerably more than one hundred feet in per- 

 pendicular height, entirely composed of coral. 

 How are these circumstances to be reconciled to 

 the position of French, and indeed of English, 

 naturalists, that madrepores, in the formation of 

 coral rocks, do not commence their labours at 

 greater depths than twenty -five or thirty feet below 

 the surface of the sea; resting their habitations on 

 the summit of submarine rocks, bringing them 

 nearer to the surface, but not forming them entirely 

 from the bottom of the ocean? I question not 

 the fact that these polypi commence their opera- 

 tions on previously existing rocky summits; nor 



do I doubt that the nucleus, on which they have 



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