SECT. 3] 



SHALLOW-WATER CARBONATE SEDIMENTS 



563 



The distribution of the epifauna can also be related to water circulation, 

 although to a lesser degree than the infauna. The distribution of the organic 

 substrata for some elements of the epifauna may be controlled by the circulation 

 of water; or some epifauna may require a combination of substrata and a specific 

 water circulation. For further discussion of these problems and references to 

 other works, the reader should consult Thorson (op. cit.) and Hedgpeth (1957). 



Studies of skeletal sediments in several areas have shown that the variety 

 and abundance of skeletal particles, like that of their parent organisms, can be 

 related to variations in the circulation of water. These relationships help the 

 marine geologist to interpret and predict the lateral and vertical changes in 

 sediment type. In addition, skeletal sediments provide the ecologist with a 

 long-term record of populations and their productivity. It can tell him some- 

 thing about the persistent fauna and flora and provide a base line for evaluating 

 living populations. 



The clearest examples of the relationships between variations in the circula- 

 tion of water and skeletal sediments occur in areas where differences in water 

 circulation are greatest. 



A. Florida 



The major environments of this region are shown in Figs. 5 and 6, and 

 Table I summarizes their differences. The differences in physical environment 

 produce quite distinct assemblages of sediment-producing organisms. In the 



Table I 

 Major Environments of South Florida (from Ginsburg, 1956, p. 2396) 



large restricted part of Florida Bay, the fauna is dominated by mollusks and 

 Foraminifera (chambers), and the flora by the lightly calcified codiacean algae 

 (sheaths). In contrast, the reef tract has a varied fauna that includes, in addition 



