THE BAHAMA ISLANDS. 



177 



crustaceans, echinoderms, and moUusks. On the beach be- 

 tween Clifton Point and West Bay (specimen No. i) the shells 

 of Strombiis gigas more especially accompany the rolled corals. 

 At East Point (specimens Nos. 2 and 3) the sand is derived 

 from corallines and nuUipores ; the finer sand being often in 

 approximately spherical grains, though not so perfectly as at 

 the White Cay (specimen No. 4) and between Exuma and 

 Long Cay. The beach near Charlotteville Point (specimen 

 No. 5) consists principally of Luciiia Pemisylvaiiica in various 

 stages of comminution. At Six Hills (Caicos Group) the mass 

 of Conch shells {Strombiis gigas) is so great and sufficiently 

 cemented together as to form not only rock, but an island 

 several hundred feet in length. Along the N.W. beach at 

 Gun Cay (specimen No. 8), a hard, coarse, stratified rock is 

 formed of Conch and other shells, together with coral fragments. 

 " The large fragments of corals and shells are never found 

 much beyond the surf-range of high-tide, and therefore always 

 form rock at a low level ; whilst on the contrary, the fine 

 calcareous sand is removed by the wind and deposited in 

 irregularly laminated beds, which, being consolidated in various 

 degrees, are converted into rock of different quahties. . . . 

 The ordinary Bahama rock everywhere consists of the above- 

 mentioned calcareous sandstone. It is somewhat similar to Port- 

 land stone in appearance, but softer and more porous. When 

 first exposed it is quite white, and is inconveniently bright and 

 dazzling under a tropical sun ; but it becomes of a dark ashen- 

 grey colour along the sea-coast, and more or less so elsewhere, 

 when exposed to the weather. Its average weight, like that of 

 the Bermuda stone, varies from 95 to 145 pounds per cubic 

 foot. Its inferior value as a building material arises from the 

 numerous sand-flaws (specimen No. 7;, and consequent ready 

 failure when exposed to the weather. About the south-west of 

 New Providence, for some feet above the sea, the rock is hard 

 and homogeneous, and may be raised in good blocks for build- 

 ing purposes. The looser and softer kinds of rock are found 

 usually on the hill tops. A variety offering a singular counter- 

 feit of true oolitic structure is found at or near White Cay, 



