FOSSIL MARINE MOLLUSCAN FAUNAS OF THE CAROLINAS: CRETACEOUS TO QUATERNARY

The Atlantic Coastal Plain has been repeatedly transgressed by rising and falling seas from Cretaceous to Holocene time, leaving signature molluscan deposits. A Recent transect across our lower Coastal Plain and continental shelf would grade from salt-wedges in our coastal rivers, to estuarine, beach, littoral, shallow sublittoral, shallow shelf, middle shelf, outer shelf, and upper slope environments. Each of these is marked by distinctive Recent molluscan index genera, and each finds expression in various fossil deposits in the Carolinas. The Uppermost Waccamaw at Calabash, North Carolina and the Corbicula-bearing beds at Aurora, North Carolina preserve coastal river biotas. Estuarine faunas include the Cretaceous at Phoebus Landing, North Carolina, and some Upper Waccamaw. Intertidal and shallow marine Donax-bearing faunas are found in the Oligocene, as well as the Upper Pliocene on the Lumber River, North Carolina, and extensively in the Late Pleistocene of both Carolinas. Mid-shelf, species-rich, sand-dwelling biotas are expressed in most Duplin and Waccamaw strata. Upwelling phosphatic hard grounds can be found in the Eocene, Miocene, and some Lower Pliocene strata. Moldic limestone hard grounds supported live-bottom reefs in the Eocene and in the Pliocene Goose Creek Limestone. Deeper shelf sand faunas can be found in the Pliocene of Brunswick, Georgia. Eocene and Oligocene deep shelf hard grounds supported siliceous sponges and benthic cnidarian communities, which provided food for large pleurotomarian gastropods and diverse large wentletraps, including Stenorytis.

Although we find fossil mollusks representative of all biotopes from coastal river to shelf-break, these localities are expressed as local, often time-averaged fossil deposits, which lack the lateral continuity required by sequence stratigraphy models.