1897.] NEW YORK ACADEMY OF SCIENCES. 115 



The great depressions in the ledge flats, the great sound, Ham- 

 ilton harbor, Harrington sound, the basins in Castle harbor and 

 the lagoon are merely " sinks " due to enormous underground 

 erosion at a time when the land was much higher than now. 

 In saying this, I merely reassert the conclusions reached by 

 Rein, Fewkes and Agassiz, which have been combatted earnestlj^ 

 by other observers. 



The flats, shoals and reefs in the lagoon and other water areas 

 are what remains after planation of hills such as surround 

 '' sinks " ou the land. The process is clear in all the water bod- 

 ies ; the undercutting on all sides of petty islands as well as 

 along tlie shores, where sandstone is the rock, extends some- 

 times more than twenty feet and the table rocks are yielding 

 daily, converting more and more of the land into shoal. A very 

 little time, geologically' speaking, will pass before half of the 

 strip between Harrington sound and the lagoon will he a shoal 

 like that along which the Causeway passes to St. George ; while 

 the cutting on the south shore promises an earlier breach through 

 the narrow isthmus separating Newton bay from the Devil's 

 hole. The whole region within the reefs was an area of dry 

 land which underwent degradation similar to that going on upon 

 the fragments which remain. 



Geological History of the Bermudas. 



We are prepared now to trace the process leading to the 

 present condition of the Bermudas. 



Prof. Rice, reviewing his observations, oflTers these conclusions 

 respecting movements : 



1. A subsidence, in which the original nucleus of the islands 

 disappeared beneath the sea, the characteristic atoll form was 

 produced and the now elevated beach rock was deposited. 2. 

 An elevation, in which the great lagoon and the various minor 

 lagoons were converted into dry land, and the vast accumula- 

 tions of wind-blown sand were formed, which now constitute the 

 most striking peculiarity of the islands. 3. A subsidence, in 

 which the soft drift rock around the shores suffered extensive 

 marine erosion, and the shore platform and cliffs already de- 

 scribed were formed.* 



Professor Rice lays much stress upon the occurrence of beach 

 rock at various localities, most of which have been referred to in 

 this paper, while at the same time he recognizes fully the feolian 

 origin of the sandstone and limestone, whicli he regards as a con- 

 tinuous deposit. He is inclined to see in the movements of the 

 Bermudas, three great movements in at least part of the North 



*Loc. cit., pp. 16, 17. 



