Recent Estuarine Sediment History of the Roanoke Island Area, North Carolina
Michael P. O’connor, Stanley R. Riggs, Don Winston, 1972. "Recent Estuarine Sediment History of the Roanoke Island Area, North Carolina", Environmental Framework of Coastal Plain Estuaries, Bruce W. Nelson
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Estuarine sediments from Croatan, Roanoke, and northernmost Pamlico Sounds in the Roanoke Island area of North Carolina demonstrate complex patterns of deposition and erosion. The sediments reflect the dynamic interplay between the fresh- and salt-water systems, as controlled by the shifting barrier island inlets from the Atlantic Ocean and the fresh-water discharge from the mainland.
Utilizing the sediment data, detailed hydrographic surveys, and the historic maps of the region, the sedimentary processes of erosion and deposition within the estuaries of the Roanoke Island area have been related to the location and changes of the major inlets along the Outer Banks. During recorded history, and prior to 1817, inlets adjacent to or north of Roanoke Island were continuously open. Evidence suggests that during this time most of the Roanoke Island area was characterized predominantly by sediment deposition within a clear, saline, and productive estuarine system having a diverse benthic marine fauna. With the closing of the last of the northern inlets in 1817, the discharge from the Albemarle drainage system was diverted around Roanoke Island, widening and deepening Croatan Sound, and producing a highly variable, turbid, brackish water environment characterized by a restricted benthic fauna. Today, Croatan Sound is characterized in the central portions by active scour that exposes pre-Holocene peats and fossiliferous fine sands, erosion of the Recent salt marshes and peat beds along the shorelines, and slow deposition of very fine and fine-grained sediments over much of the rest of the area. Northernmost Pamlico Sound is characterized by a shifting erosional-depositional regime to which fine-grained sand is supplied by the tidal currents of Oregon Inlet. Roanoke Sound is characterized primarily by a depositional regime in which fine sand, derived from the Atlantic system by wind action and storm washover, is actively filling the shallow sound.