FLORIDA REEFS AND KEYS. 205 



structure of the Florida limestone. This structure is seen 

 where one would be led to expect it, in the tine grained seams. 

 A few hundred yards from the hospital a quarry has been 

 opened where the rock may be examined. The organic re- 

 mains consist of broken shells and water-worn fragments of 

 corals, which, both in species and state of preservation, resemble 

 those on the shores of the island. Except in degree of hard- 

 ness, the rock does not differ from the calcareous sands thrown 

 up by the waves on the shore in the vicinity ; and the condi- 

 tions presented by the loose moving sands, are not favorable 

 to the habits of molluscous animals, nor are fossil shells very 

 abundant in the limestone of the island. Oblique or false 

 stratification is everywhere seen in the rock, the inclination of 

 the planes differing very little from the slope of the shore up 

 which the waves push dead shells, pieces of coral, etc. After 

 a breeze, coarse materials are found strewing the beach, a 

 light wind leaves a finer deposit, and in the succeeding calm 

 the sea appears milky from fine calcareous matter suspended 

 in the water; this is deposited in the form of free, impalpable 

 mud, which invests marine plants and other objects, to which 

 it adheres with great tenacity, and becomes a source of annoy- 

 ance to the collectors of Algos. All these alternations of fine 

 and coarse materials may be observed in the limestone. [The 

 rock corresponds to the beach sand-rock.] 



" Along the south beach, the sand is thrown up by the 

 waves to an elevation nearly equal to that of the highest point 

 of the island, and during the gale of Oct. 1841, the greater 

 part of it was submerged, so that, at first sight, it might ap- 

 pear that the whole island was the result of sand thrown up 

 at such times. But although I observed no beds in the lime- 

 stone that prove, like those of our Tertiary, that the animals, 

 whose remains they contain, lived and died on the spot, yet 



