EEPOET ON THE FLORIDA REEFS. 



REPORT OF PROFESSOR AGASSIZ TO THE SUPERIFTEN'DEISrT OF THE COAST SURVEY, ON 

 THE EXAMINATION OF THE FLORIDA REEFS, KEYS, AND COAST. 



Cambridge, August, 1851. 



Sir, — The following report of the examination made by me of the Florida 

 reefs, keys, and coast is prepared in compliance with your request. 



Topography of Florida. 



To form a correct idea of the Florida reefs, it is of paramount importance 

 to keep in mind the topographical features of the whole country. The 

 peninsula of Florida projects between the Gulf of Mexico and the Atlantic, 

 from the 30th degree of northern latitude nearly to the 24th, as a broad, 

 flat, low promontory, which has generally been considered a continuation of 

 the low lands of the Southern States. But, as we shall see hereafter, this is 

 not the case, or, at least, not with respect to the southern extremity of the 

 peninsula, which consists of the same formations as the reef itself Again, 

 in a physical point of view, Florida is not limited to those tracts of land, 

 forming the peninsula, which rise above the level of the sea, for the exten- 

 sive shoals along its southern extremity, between the main-land and the 

 keys and reefs, as well as those extending to the west as far as the Tortugas, 

 whence they stretch along the western coast, in fact belong to it, and are 

 intimately connected with it, by their physical character. There is a similar 

 tract of flats along the eastern shore, but it is not so extensive as on the 

 southern and western shores, nor does it partake as largely of the peculiar 

 character of the peninsula, being chiefly formed of the alluvial sand, drifted 

 ashore by the waters of the Atlantic. 



We shall have occasion, however, to show hereafter that the narrow 

 longitudinal islands, which extend close to the main-land almost for the 



