1897.] NEW YORK ACADEMY OF SCIENCES. 117 



rock, since marine forms have been found by Heilprin as well as 

 by himself in rocks unquestionably a^olian.* The so-called 

 beach rock is at no higher elevation than if thrown up by a gale. 

 On Ireland island it rests on leolian beds fift3^ feet below water 

 mark.f 



Respecting movements, he concludes that : 



We need only a single subsidence to explain all the phe- 

 nomena, if, as I have suggested, base rock is only modified a^olian 

 rock, and beach rock has been forming continuously, and the 

 teolian hills were formed at the time when the atoll was one gi- 

 gantic annular beach, constantly receiving fresh material from 

 the outlying reef This primordial reef has diappeared and its 

 remnants exist perhaps at depths of twent}^ fathoms or more 

 near tlie edge of the bank.;}; 



In view of all the facts, one cannot resist the conclusion that 

 at one time the outer limit of the Bermuda land area was near 

 the present twenty-fathom line. Whether or not the land origin- 

 ally was an elliptical reef enclosing a lagoon cannot be deter- 

 mined now and the character of the rock underlying the lime- 

 stone can be ascertained only by a deep boring. The limestone 

 itself is unquestionably of aeolian origin, but it extends to a very 

 considerable depth below water level, as is shown by the presence 

 of huge stalagmitic columns, thirty feet below tide level in cav- 

 erns between Harrington sound and Castle harbor and by the 

 ascertained presence of the limestone itself in the excavations at 

 Ireland island. The altitude, with relation to tide, must have 

 been sufficient at one time to bring the floor of the caverns at 

 least several feet above tide. As the extreme depth of Harring- 

 ton sound as reported by Professor Heilprin is sixteen fathoms, 

 the floor could hardl3' have been less than one hundred and 

 twenty feet higher tban now. 



It is difficult to regard, without sharp limitations, the lime- 

 stone as part of a continuous teolian deposit of which the sand- 

 stone and dune are the later portions, as Professors Thomson, 

 Rice and Agassiz have done. That the formation of aeolian rock 

 has been continuous since land first appeared no one can doubt; 

 but it is equally certain, as far as the present land area is con- 

 cerned, that at one time and for a long time the accumulation of 

 dune sands almost ceased or was confined to a narrow space along 

 the shores. It is equally difficult to understand how the consoli- 

 dation of the limestone could be due to the action of seawater,as 

 has been suggested, for the rock is the same in the Ireland island 



« A visit to the Bermudas In March, 189 J, p. 228. 

 tLoc. cit., p. 221. 

 JLoc. cit., p. 224. 



