The oolite facies contains 

 localized layers of calcite which 

 generally increase in crystalline 

 structure with depth (Cinsburg 

 1954). As one proceeds down in the 

 oolite, many of the aragonitic ooids 

 and pellets have been entirely or 

 partially replaced by calcite. In 

 the lower levels beneath the water 

 table, many of the ooids and pellets 

 have themselves been completely dis- 

 solved, leaving only cavities in the 

 calcitic cement. Hoffmeister et al. 

 (1967) refer to the character of 

 this cavity ridden limestone rock as 

 oomoldic. 



In physical appearance the 

 oolitic facies may often be cross- 

 bedded, i.e., exhibit longitudinal 

 ridges oriented at varying angles to 

 one another. These are more promi- 

 nent on the seaward side than on the 

 Everglades side of the Atlantic 

 Coastal Ridge. The crossbeds are 

 believed to have formed as a result 

 of the complex tidal and wave action 

 to which the ridge was exposed. 



On the western side of the 

 coastal ridge the oolitic facies 

 slopes gradually down toward the 

 Everglades, slowly decreasing in 

 thickness over the distance of a few 

 miles. In its place the underlying 

 bryozoan facies of the Miami Lime- 

 stone is exposed at the surface 

 (Figure 23) . 



The bryozoan facies, which 

 averages 3 m (10 ft) in thickness, 

 consists of large numbers of massive 

 tubular cheilostome bryozoan com- 

 pound colonies, primarily Schizo - 

 porella floridana . Many of these 

 colonies are 30 cm (1 ft) or more in 

 diameter. As outlined in Figure 23, 

 the bryozoan facies underlies the 

 oolitic facies beneath all but the 

 southern tip of Taylor Slough. Here 

 and southward to the upper Keys the 

 oolite appears to be continuous down 



to, or contemporaneous with, the Key 

 Largo Limestone. A fair number of 

 fossil corals, especially branching 

 Porites sp., are found along this 

 strip in place of the bryozoans. 



Hoffmeister et al. (1974) de- 

 scribe the occurrence of two main 

 growth forms of bryozoan colonies: 



(1) those that are rough irreg- 

 ular masses with knobby 

 subcylindrical projections 

 that vary greatly in size; 

 these are the more numerous 

 group as well as generally 

 larger in size; and 



(2) a smaller size form, 10 to 

 13 cm (4 to 5 in) at most, 

 also irregular with crooked 

 branches emanating from a 

 bumpy base. The tubes have 

 a tendency to flange out 

 near the tops. 



In their present environment, bryo- 

 zoans in Florida Bay are often found 

 encrusting around gorgonians, blades 

 of sea grasses, and green algae. 

 This same growth form is evident in 

 the geologic record of the "Miami 

 Limestone". 



As the shallow seas slowly 

 retreated, the submerged oolitic bar 

 (now the Atlantic Coastal Ridge) 

 gradually emerged as dry land. 

 During this slow retreat tidal chan- 

 nels were cut through the unstable 

 oolite, connecting the shallow sea 

 that lay over the present Everglades 

 with the Atlantic Ocean to the east. 

 These tidal channels can be seen 

 today in the Atlantic Coastal Ridge 

 as complete or partial transverse 

 cuts and valleys often called 

 "Transverse Glades" (Davis 1943). 

 Some of these contain major fresh 

 water streams and canals, while 

 others are overlain by sand or shell 

 deposits. One of the larger of 

 these relict tidal channels connects 

 Taylor Slough head waters with upper 

 Taylor Slough. 



53 



