22-4 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



necessarily so. The base rock, considered by some of the writers on the 

 Bermudas to underlie the ajolian hills, I look upon as the modified part 

 of the lower portion of the teolian strata chano:ed into a hard riui'inf 

 limestone in wliicli all traces of stratificAtion have often disappeared 

 (Plates XVL-XVIIL). 



Heilprin argues tiiat the beach rock has been elevated and is still 

 found at an elevation of 12 to 16 feet; that it "antedates the last 

 subsidence, ... is at least as ancient as the lagoons and sounds, and 

 probably much more ancient. Indeed, there is nothing that could lead 

 one to suppose that it is not the original rock which was formed when 

 the island first came to the sm-face. Although now exposed on the sea 

 border, it is really an interior rock, as is proved by the broad band 

 of land which must have been i-emoved from the seaward side of the 

 existing cliffs." i But this neither indicates elevation, nor that it is an 

 original beach rock, since at the western extremity of the Bermudas, at 

 Ireland Island, it is underlaid by true a;'olian beds fifty feet below low- 

 water mark. It does not seem to mo tliat beach rock is found at any 

 greater elevation than that at which it could have been thrown up (and 

 subsequently cemented) during a hurricane or violent gale. 



The shore platform of which Professor Rice speaks appears to con- 

 sist only of modified seolian strata, changed into hard ringing rock by 

 the action of the sea, and of a shore platform eroded to ledges, as he 

 himself describes them. He well says, when speaking of the relation 

 between drift and beach rock on the south shore, "If we conceive the 

 seaward face of the dune to \)e restored, it would certainly in some 

 localities extend beyond the narrow shore platform into the area now 

 covered by the sea." 



Can we not find a simpler explanation of the formation of the Ber- 

 mudas than the one suggested by Rice 1 Instead of a subsidence 

 during which the nucleus disappears, followed by an elevation during 

 ■which the seolian hills were formed, and then by a subsidence during 

 which the present soft drift rock was eroded, as is suggested by Rice, 

 we need only a single subsidence to explain all the phenomena, if, as 

 I have suggested, base rock is only modified seolian rock, and beach 

 rock has been forming continuously, and the seolian hills were formed 

 at the time when the atoll was one gigantic annular beach constantly 

 receiving fresh material from the outlying reef. This primordial reef 

 has disappeared, and its remnants exist perhaps at depths of from twenty 

 fathoms or more near the edge of the bank. 



^ Bermudas, p. 43. 



