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Clam and oyster beds are quite intimately related to both the 

 bay or estuary where they are located and the nearby marshes 

 which provide the production which the shellfish, in part, 

 harvest. Shellfish are sessile as adults and are quite sensitive 

 to siltation. Some species such as oysters (Crassostrea vi rginica) 

 lack the siphon that permits clams to be buried by silt. Clams 

 are also dependent on detritus from marshes for food, especially 

 in the younger stages. Adult crabs (Callinectes s apidus) may feed 

 in turn on smaller detritus feeders. Although crabs are quite 

 mobile and migrate during the winter into deeper water near the 

 mouth of the Bay, their attraction to certain areas in the 

 summer reflects the high productivity of those areas. These 

 places should be identified wherever possible as well as oyster 

 bars and clam beds . 



Paleontological Features 

 Fossils, mostly of Miocene age (25,000,000 years before 

 present), are abundant in many exposed Bay front areas: Calvert 

 Cliffs is probably the best known example. The nature of the 

 material (snail shells, shark teeth, whale bones) and its age 

 give glimpses into the past continuum of environments leading to 

 the present. More than any other geological feature, fossils 

 bring home to the general public the meaning of geological 

 time. Fossil sites were given consideration in this survey, 

 but they generally included few ecologically valuable features 

 and received low ratings. 



