18 THE GEOLOGY OF BERMUDA. 



that the great oceanic subsidence recorded by the coral islands of trop- 

 ical seas was the counterpart of the great elevation of the continental 

 lands in the Glacial Period.* It is not improbably a legitimate follow- 

 ing out of this suggestion to recognize, in the three great movements 

 which are indicated for at least a part of the i^orth Atlantic basin by 

 the geological phenomena of Bermuda, the counterparts of the three 

 great movements of the North American continent which have charac- 

 terized in American geology the epochs of the Quaternary Age. The 

 great subsidence in which the Bermudian atoll was formed, would then 

 be recognized as correlative with the Glacial elevation of the continent. 

 The epoch of elevation in which the Bermudian lagoon was converted 

 into dry land, would correspond with the Champlain subsidence of the 

 continent. And the final subsidence, of which Bermudian geology 

 aifords evidence so manifold, would correspond with the re-elevation of 

 the continent which marked the transition to the Terrace or Kecent 

 Epoch. 



While we may reasonably conclude that Bermuda, in common doubt- 

 less with an area of the North Atlantic of very considerable extent, has 

 undergone these comprehensive movements, it would be strange if 

 there had not occurred at least locally minor oscillations. Such oscil- 

 lations may possibly be indicated by the stones reported by Nelson as 

 occurring in the layers of "red earth" in Ireland Island.t His state- 

 ment, however, is somewhat indefinite. At one locality on the south 

 shore, a short distance west of Tucker's Town, I observed a hard layer 

 of rock containing marine shells immediately overlying a soft layer con- 

 taining land shells. The clearest evidence, however, of repeated oscil- 

 lations of level is afibrded by a remarkable locality on the north shore 

 of Stock's Point. The rock which has been quarried there, and which 

 now appears in the base of the bluff, is a very hard rock of subcrystal- 

 line texture and of ferruginous color. It shows vestiges of irregular 

 lamination, and contains fossil Helices and no marine fossils. It is 

 undoubtedly a drift-rock, like that at Paynter's Vale. The upper sur- 

 face of this rock is exceedingly irregular, giving evidence of much sub- 

 aerial erosion preceding the deposition of the overlying strata. It is 

 overlain by a remarkable conglomerate, evidently a beach-rock, con- 

 taining fragments of the underlying hardened drift-rock, i)eculiar ferru- 

 ginous nodules, compact lumps of " red earth," and pretty large marine 



* Corals and Coral Islands, pp. 366-372. 

 tOj;. cit, p. 118. 



