610 PROCEEDINGS OF THE ACADEMY OF [NoV., 



dried up, became in places fresh, so that fresh-water forms could 

 live in it and become mixed with the already deposited marine forms 

 and the land forms. The wells near this St. George's locality show 

 much sodium chloride in the water, as though it might have passed 

 through a salt-pond stage. Such salt-pond deposits may have formed 

 during the last stages of the rising of the island from the submergence 

 at the time of the deposit of the shell layers in the Central Plain, 

 already noted. Salt ponds now occur along the west coast of the 

 island, but I did not personally observe them along the east coast; 

 these "raised beaches" are probably such deposits in the limestone 

 along the east coast. They are not likely to be of any great antiquity, 

 and are not greatly different in their origin from what is now forming 

 in the salt ponds of the western side of the island. 



9. Salt Pond and Mangrove Swamp Deposits. 



As just noted above, these deposits are characteristic of certain 

 places on the western shore line, from Corbizon Point to the vicinity 

 of St. Mary's, Old Road. They are shallow bays that are gradually 

 filling up. They are seen in all stages of development, for instance 

 in the region of the head of Five Islands Bay and between this and 

 St. John's Harbor. Salt pond deposits exist about a mile beyond 

 the Union Sugar Mill. Evidently here a connection existed at no 

 very distant time between Five Islands Bay and St. John's Harbor, 

 and, indeed, upon Nugent's map this district is represented as a 

 swamp. This same map shows a bay open to the sea east of the 

 stretch of beach between Dry Hill and Corbizon Point, where a 

 salt pond now exists; and open water on the north side of St. John's 

 Harbor where a salt pond is now forming. Some ten such salt ponds 

 are shown upon this Nugent map from Ships Stern (at the entrance 

 of St. John's Harbor) to St. Mary's, Old Road. These shallow bays 

 are first cut off from the sea by the growth of mangroves and such 

 plants as can exist in presence of the salt water; a fringe of such 

 mangroves near the mouth of the bay becomes a place for deposition 

 of sand and other inorganic matter washed up by the waves, and a 

 sand tract forms, cutting off the mouth of the bay. This bar grad- 

 ually grows until the salt water only reaches in to the pond in time of 

 high wind or tide. The water in the pond becomes brackish from the 

 surface drainage getting into it, and the salt-water forms living 

 in it, when freely open to the sea, are killed off, giving place to 

 brackish-water and finally to fresh-water forms, if the pond continues 

 to exist so long. When such a pond is near higher ground, the 



