FREE INSTITUTE OF SCIENCE 



59 



VEGETATION OF SOUTH FLORIDA 



Largo limestone formed from the ancient coral reef. The writer believes 

 that the evidence of the vegetation is sufficient to prove that, although 

 contemporaneous, or even earlier, in formation than the Miami-Key West 

 oolitic deposits, the Key Largo limestone was elevated later above the 

 surface of the sea, thus forming a land bridge between the disconnected 

 areas of Miami-Key West on the mainland and in the extreme western 

 groups of keys. The evidence for this view will be presented subsequently. 



Lostmans River limestone is a non-oolitic fossiliferous one, which 

 apparently underlies the western coast of southern Florida with outcrops 

 exposed inland. These limestones underlie the gray sands of the main- 

 land, the marls of the coastal swamps, the islands of the southern portion 

 of the Ten Thousand islands, and extend along the southwestern border of 

 the Everglades. The stratigraphic position of this limestone has not been 

 determined with exactness. Sanford* thinks that the Miami-Key West oolite 

 is younger than the non-oolitic limestones which lie between its north and 

 south divisions, and the fact that in general the west coast of Florida is older 

 than the east coast and the facts of plant distribution lend support to this view. 



There is a widespread covering of sands through the central part of the 

 peninsula of Florida and these sands extend southward to Miami on the 

 east coast and to Everglade on the west coast. These sands have probably 

 been blown inland from the material carried southward along the eastern 

 shore of North America by oceanic currents. At the surface, the sands are 

 white or gray, below the surface they are of yellow, orange, and red hues. The 

 deposits in southern Florida of recent age consist of peat, of marl, of sands, of 

 coral reefs, and of oyster banks. The peat has been formed most extensively 

 to a depth of one to two meters (about six feet) in the Everglades. The marls 

 have been laid down on beaches, in swamps, and in lagoons and on the sea 

 bottom, such as the limey oozes that cover wide expanses of the bottom of the 

 Bay of Florida and elsewhere. The recent quartz sand deposits are those of 

 the beaches and the wind-blown sand of the dunes. On the east coast these 

 end with Key Biscayne, for the beach sands of Soldier Key and the series of 

 islands extending to Key West are calcareous. The recent coral reefs are found 

 off the arc of the Florida keys from Soldier Key to the Tortugas, and they are 

 of the barrier type. The seaward slope is steep, but the living coral polyps 

 carry on their work in water one and a half to 8 meters deep, where heads and 



* Sanford, Samuel: Second Annual Report Florida Geological Survey, p. 219. 



