PHYSICAL HISTORY AND GEOLOGY. 43 



It becomes an interesting question to ascertain how far 

 elevated above water-line the Bermudas were at the time when 

 they formed a continuous island. The data that are presented 

 for the determination of this problem are mainly of a negative 

 character. But if a subsidence of some 50 or 60 feet can be 

 indicated, and we still have beach-rock on the islands at an 

 elevation of some 12-1G feet, it will be necessarily assumed 

 that the actual uplift above sea-level was at least 60 or 70 feet, 

 unless, indeed, the movement was not a uniform or coincident, 

 one for the entire island group. This last assumption seems, 

 however, highly improbable. It may, again, be assumed that 

 the elevated beach-rock was lifted since the period of sub- 

 sidence, and represents the closing movement of the land. 

 Its presence therefore need not argue for elevation beyond that 

 which is indicated b) its own highest level, some twelve or 

 fifteen feet. But the relation of this rock to the drift-rock 

 overlying it, and the fact that the latter in so many places 

 drops bodily into the sea, forbid such a conception. The 

 beach-rock is manifestly old, and long antedates the last sub- 

 sidence; and for anything that can be shown to the contrary, 

 it 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 surface. 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 

 removed from the seaward side of the existing cliffs. 



Two questions present themselves at this stage of the inquiry. 

 One of these has been much used of late by the opponents of 

 the Darwinian theory of coral formations, and bears upon the 

 formation of lagoons through aqueous solution. The second 

 considers the amount to which a possibly cavernous condition 

 of the island may have facilitated the work of the erosion, and 

 permitted of the present features having been formed without 

 the aid of subsidence. 



