Okeechobee. However, Brooks (1968) 

 later renamed it the Lake Flirt 

 Formation to include muck layers 

 sandwiched in between the distinct 

 marl beds. Due to the low relief of 

 the area and its recent emergence 

 from the sea, erosional soils are 

 generally non-existent or poorly 

 developed (Davis 1943). 



It is generally agreed (Davis 

 1943, Parker and Cooke 1944, Davis 

 1946, Gleason et al. 1974) that the 

 distribution of surface sediments 

 and soils in south Florida closely 

 follows bedrock geology and hydrol- 

 ogy. Underlying bedrock topography 

 is characterized by two troughs 

 corresponding to Shark River and 

 Taylor Sloughs. In contrast, these 

 distinctive features of the bedrock 

 topography are nearly obliterated in 

 the surface topography. Due to peat 

 accumulation and/or the deposition 

 of fresh or brackish water calcium 

 carbonates, surface relief tends to 

 become flattened out. 



Within the lower Everglades and 

 Taylor Slough study area, there are 

 two major divisions of Holocene 

 sedimentary sequences: 



(1) that area in which cores to 

 Pleistocene bedrock reveal 

 no brackish water sequences 

 of marl or peat and 



(2) that area in which cores 

 indicate (primarily through 

 the presence of Rhizophora 

 peat) an inundation by 

 brackish, marine conditions 

 at some time in the recent 

 past. 



The Everglades are character- 

 istically dominated by herb covered 

 marshes and forested swamps. Saw- 

 grass ( Cladium jaimaicenis ) , a 

 sedge, generally prevails over the 

 majority of the landscape, often to 

 the apparent exclusion of all else. 

 Interrupting this river of grass are 



numerous, relatively small forested 

 areas that may be elliptical, round, 

 or tear-dropped in shape. These 

 are variously referred to as tree 

 islands, heads, keys, cones, or ham- 

 mocks (Craighead 1971). The shape 

 of individual islands is believed to 

 be a function of surface hydrology 

 (Davis 1943, Loveless 1959). Ellip- 

 tical islands are prominent in the 

 relatively fast flowing Shark River 

 Slough, while rounder islands are 

 more characteristic of the drier 

 areas north of Florida Bay. The 

 "tails" of tree islands are often 

 found to be growing in furrows of 

 the bedrock (Craighead 1971). 



There are different types of 

 islands, and many are successionally 

 related to one another. Some origi- 

 nate on bedrock highs where the 

 slight elevation difference allows 

 colonization by true terrestrial 

 vegetation. Subsequent deposition 

 and trapping of organic matter re- 

 tains this initial elevation advan- 

 tage. Other islands such as the 

 "bay head" are usually found in 

 bedrock depressions which are built 

 up to a low mound of organic soils 

 above the surrounding marsh. Still 

 others, such as the cypress and wil- 

 low heads, exhibit little or no peat 

 buildup above average high water. 

 Spackman et al. (1964) describe a 

 sequence of events whereby cypress 

 initially colonizes a wet area and 

 gradually succeeds into a bayhead. 

 Figure 24 presents cross sectional 

 profiles of these two types of tree 

 islands. 



In the cypress island, the un- 

 derlying veneer of fresh water marl 

 suggests that the area was once a 

 spikerush ( Eleocharis dominated) 

 marsh where deposition of calcium 

 carbonate by the marl producing 

 algal mat was once very active. 

 Note that the marl appears perfora- 

 ted by the peat, a characteristic 



57 



