only one small lagoon-like body of 

 water appears, i.e.. Tarpon Bay in 

 the Harney River. Farther north, 

 however, beginning at Lostmans 

 River, back bays become a prominent 

 feature of the landscape. This 



feature continues and expands to the 

 north within the Big Cypress drain- 

 age basin culminating in the Ten 

 Thousand Islands area south of Cape 

 Romano. 



Cape Sable 



One of the most distinctive 

 features of the southwestern tip of 

 Florida is Cape Sable. White (1970) 

 claims that the cape overlies a de- 

 generate westerly extension of Miami 

 Limestone of the Atlantic Coastal 

 Ridge. He refers to the terminal 

 end of this extension as the "Cape 

 Sable High". The forefront of the 

 cape actually exhibits three dis- 

 tinct capes: the Northwest Cape and 

 the Middle Cape, which are quartz 

 sand covered capes; and the East 

 Cape, which contains relatively more 

 marl (Craighead 1971). 



The present beaches are surface 

 exposures of buried coquinoid ridges 

 which constitute a major portion of 

 the underlying strata of the seaward 

 cape. Behind these beaches and 

 beach ridges, the cape is separated 

 from the nearest surface bedrock by 

 a broad expanse of marl and peat, 

 and Whitewater Bay. These marl and 

 peat areas are vegetated with salt 

 marshes, mangroves, salt prairies, 

 and tropical hardwood hammocks 

 (Craighead 1971, Browder et al. 

 1973). 



It is believed that the beaches 

 at Cape Sable first formed as a 

 result of a shallow submarine scarp 

 cut into the bedrock (White 1970). 

 This wave-cut notch allowed local- 

 ized wave breaking long enough for 

 a bar to be built and a barrier to 

 be formed. The subsequent growth 

 of shellfish offshore continued 

 to feed the beach with shell and 



sand, particularly during hurricanes 

 (Craighead 1971). 



The coastal prairies behind the 

 beaches of Cape Sable are composed 

 of a succession of troughs and low 

 dunes (Craighead and Gilbert 1962). 

 On the upland side of these prai- 

 ries, the highest elevations support 

 a continuous ridge of hammocks 

 (Craighead 1971, Browder et al. 

 1973). A series of shallow ponds, 

 the largest of which is Lake 

 Ingraham, extend from the north of 

 the Middle Cape east to Flamingo. 

 Craighead considers these ponds to 

 be remmants of former open waters 

 that have not been completely filled 

 by surrounding marl and peat. Water, 

 when present in these troughs, can 

 be either fresh or saline depending 

 on local hydrologic conditions. 

 White (1970) characterizes inland 

 Cape Sable as an isolated pocosin 

 sloping gradually down from a peat 

 dome toward the Joe River and White- 

 water Bay. 



North of the Northwest Cape, 

 beach sand is less apparent owing to 

 the more gradually sloping submarine 

 topography and the increased influ- 

 ence of freshwater glades runoff. 

 Craighead (1971) singles out Big 

 Sable Creek as an area where the 

 creek delta and beach are actively 

 receding with rising sea level. The 

 erosion forces which are believed to 

 be at work in forming the Big Sable 

 Creek coastline environment are as 

 follows : 



(1) Shoreline mangroves are kil- 

 led by deposits of hurricane 

 mud; 



(2) Storm tides gradually erode 

 unconsolidated sediment; 



(3) Trees are toppled and car- 

 ried back to sea by hurri- 

 cane backwash. 



The types of shorelines that border 

 the lower Everglades coast and their 

 approximate geographic extent are 

 summarized in Figure 6 (Spackman 

 et al. 1964). 



16 



