AGASSIZ: BAHAMAS. 83 



steep beach, the summit of which is from twelve to fifteen feet above the 

 level of the sea. The sea face is not more than twenty to thirty feet wide, 

 ■while on the lagoon side the beach is from three to five hundred feet 

 wide. As has been noted by other observers, tlie water of the lagoon is 

 intensely salt. We saw nothing living in it, but many dead conchs and 

 the shells of other large mollusks, as well as those of innumerable 

 smaller mollusks were found scattered all along the lagoon beach. These 

 mollusks must liave lived in the lagoon during a higher stage of water, 

 when its salinity did not differ materially from that of the sea. It is 

 surrounded by mangroves, many of which run far into the lagoon. Tlie 

 hills to the east are not more than twenty-iive feet in height. I could 

 not satisfy myself of their true character, and could not decide from what 

 I observed whether the rocks composing them were seolian, or whether 

 they had been thrown up during hurricanes, as was undoubtedly the 

 case with a bluff which forms a part of the same low range separating 

 the lagoon from the sea. This bluff was built up of large rectangular 

 blocks of coral rock similar in structure to that of the inclined strata 

 along the shores. Some of the blocks had been thrown up to a height 

 of fully twenty-five feet above the level of the sea during the hurricane 

 of 18G6. At least our pilot says that is the general report. 



Between Salt Cay and Double Headed Shot Cays as far as Rompidas 

 Rocks we steamed on the edge of the bank in about seven to eight 

 fathoms over masses of coral heads closely clustered together, separated 

 by narrow sand bars consisting of Astrteans and other corals. At our 

 anchorage off Salt Cay the coral heads were growing luxuriantly in from 

 three to five fathoms. The great abundance of living corals on the edge 

 of the Salt Cay Bank fully accounts for the masses of fragments of 

 corals in all stages of comminution which we found on the beach of Salt 

 Cay, and for the formation of an island like Salt Cay, which is probably 

 wholly of reef-rock sand origin, and not of fpolian origin like the other 

 cays on the northern and eastern edges of the bank. After making the 

 shallower water of the bank, the coral heads are fewer, there are longer 

 stretches of sand between the heads, and large spaces entirely devoid of 

 corals. 



Salt Cay Bank is, like the other banks of the Bahamas, a triangular 

 plateau fringed on the eastern and northern edges with islands and islets 

 or isolated rocks all of seolian structure, while on the western edge of the 

 bank, with the exception of the Rompidas and Lavanderas Rocks, they 

 have disappeared. The subsidence of the bank has probably been 

 fully as great as that of many of tli« other banks, if we are to judge 



