shell material in the turbulent beach environment, especially where the shell 

 material is mixed with substantial amounts of quartz sand. 



It is not uncommon to encounter shell material that has been produced in 

 an earlier time under different envirormiental circumstances than the present 

 (relict material). From North Carolina to Florida, relict material may be a 

 significant element in coastal deposits. One way in which coastal deposits 

 may be preserved is by secondary diagenetic changes. An example is the 

 formation of beach rock, which involves the consolidation of beach sand by 

 interstitial cement composed chiefly of calcium carbonate (Higgins 1968). For 

 example, the Anastasia Formation beach rock, a coquina limestone, may 

 outcrop in the surf zone as nearshore reefs or as a low cliff in the berm area 

 (Figure 9). 



In addition to contributing sediment particles, several organisms are 

 capable of building reefs on the sea floor. Corals are the best known reef 

 builders and usually produce the largest reef structures. However, various 

 types of worms, mollusks, bryozoa, and coralline algae are also capable of 

 reef construction. 



Figure 9. 



Outcrops of Pleistocene coquina rock of the Anastasia Formation on a beach in 

 East Florida. Erosion of such rocks contributes sediment particles to the beach 



26 



Chapter 2 Relevant Processes and Factors 



