Sediments of the panhandle and peninsula dif- 

 fer in origin and basic character partly because 

 rivers of the panhandle drain areas in the Ap- 

 palachian Mountains, the Piedmont Plateau, and 

 the coastal plain whereas those of the peninsula 

 drain only coastal plain areas. Panhandle sed- 

 iments are mainly clastic; peninsular sediments 

 are mainly nonclastic, predominantly carbonates 

 and anhydrites. The Apalachicola Embayment 

 and the South Florida Embayment are synclines 

 (Fig. 28). 



Sea level has varied from +270 to —525 ft 

 ( + 82 to — 160 m) in relation to present sea level. 

 Wave-cut terraces above sea level and relict spits 

 and coral reefs below it have helped geologists 

 to identify ten previous stands of the sea. The 

 terraces were thought to be Pleistocene in age, 

 correlating with glaciations of the past 300,000 

 years, but evidence exists of pre-Pleistocene or- 

 igin of the terraces that are at elevations of 100 

 ft (30 m) and above (Schnable and Goodell, 

 1968). The earth is currently in an interglacial 

 stage in which the polar ice caps are melting, 

 a process that began most recently about 14,000 

 years ago when sea level may have been 525 ft 

 (160 m) below the present level (Ballard and 

 Uchupi, 1970). Over the past 4,000 years the 

 rise totaled only 10 ft (3 m) , an average flooding 

 of 5 inches (13 cm) per 100 years (Scholl, 1964). 

 The flooding produced Florida Bay, which is a 

 drowned lacustrine plain, and the coastal estu- 

 aries such as Tampa Bay, which are drowned 

 river valleys (MacNeil, 1950; Price, 1954). 



Florida's topography consists of lowlands and 

 highlands of which the coastal lowlands are most 

 relevant to this discussion. The Terraced Coast- 

 al Lowlands with marine terraces at 5, 25, 42 and 

 70 ft (2, 8, 13 and 21 m) terminate at the 70-ft 

 (21-m) contour. The highlands, maximum ele- 

 vation 345 ft (105 m), have marine terraces at 

 100, 170, 215 and 270 ft (30, 52, 66 and 82 m) 

 (Fig. 31). 



The prolific ground-water resources of Flor- 

 ida supply wells and some of the world's largest 

 springs. Aquifers are of two types: artesian 

 and nonartesian. The artesian aquifers are 

 those in which the pressure of water is sufficient 

 to force water above a containing formation of 

 relatively impermeable material (rock or clay) 

 whereas no containing formation is present in a 

 nonartesian aquifer, leaving the water level 

 (water table) free to rise and fall. The Floridan 



Figure 31. — Topographic divisions (after Puri and 

 Vernon, 1959). 



Figure 32. — Principal aquifers (after Hyde, 1965). 



Aquifer, the State's largest, is artesian; all 

 others are nonartesian (Figure 32). 



STREAM DISCHARGE 



Florida is one of the wettest states in the 

 Union with annual rainfall of 50-65 inches (127- 



54 



