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BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



is a submerged flat underlain by gently dipping limestones there are 

 offshore reefs, some of which have the barrier form. Where there 

 are extensive offshore flats at the proper depths, if the other ecologic 

 conditions are favorable, reef corals grow upon the surface of the 

 flats and form either patches, stacks, or barriers. 



N. 5gg level 



Sea level No.2 , . Sea level 



SABA ISLAND 



"a-B" 



0-fe 

 1,000 



\fiOO- 



NORTH SIDE OF ST THOMAS. 



2 4 6 6 



1 u I I 1 I ■ ' I 



Nautical' miles 



NORTH SIDE OF ST.CROIX, 



Nautical miles 



EAST COAST OF ANGUILLA 



PEDRO BANK 



HOSALINO SANK FUNAFUTI ATOIU 



FIO. 19.— TYPES OF WEST INDIAN SUBLITTORAL PKOFILES AND PROFILE OF FUNAFUTI ATOLL. 



It seems that no one would try to explain Saba, RosaUnd, or Pedro 

 Bank as the result of infilling behind barrier reefs. They are subma- 

 rine plateaus, leveled by planation agencies, which almost certainly 

 were both subaerial and submarine, and they have been submerged in 

 Recent geologic time. There is a rather meagre growth of reef corals 

 on their windward sides; but these banks are scientifically of great 

 importance, for, except that the coral growth is not so luxuriant, 

 they essentially duplicate the great atolls in the Pacific. 



