tended to open near the sites of past inlets. Sites where 

 inlets existed in the past 400 years (see Figure 9) are 

 (1) Nags Head to Rodanthe and (2) Duck, North Carolina, to 

 the Virginia State line. 



Oregon Inlet, the only unstructured inlet that has been open 

 in the study area for the entire study period, apparently af- 

 fected the ocean coastline at least 8 km north and probably 

 8 km south of its 1980 location (Figure 37). Shoreline changes 

 to the south were masked by the opening and closing of New 

 Inlet. Shore erosion decreased exponentially away from the 

 inlet (Figure 28) . A rough calculation of ocean shoreline 

 losses and Pamlico Sound sand gains indicates that nearly all 

 the Atlantic Ocean sand lost from 8 km north and south of the 

 inlet was deposited in Pamlico Sound. This net movement of 

 sand in a westerly direction could, on a time scale of hundreds 

 or thousands of years, be a major factor in island migration. 

 Today, inlet processes are the major mechanism for moving lit- 

 toral sand in a westward direction. Wind is probably second in 

 importance. 



Because of near-continuous southward migration of Oregon Inlet 

 (about 29 m/year) , the amount of littoral sand trapped in the 

 flood-tidal shoals of Pamlico Sound appears to have been con- 

 stant through time (about 3 x 10 cu m/year (Figure 40)). 



Evidence of inlets that closed before 1585, most notably at 

 Kitty Hawk, suggests the islands have not moved appreciably 

 (i.e., not more than one-fourth the island width) in at least 

 the past 400 years (Figure 12) . 



Capes affect adjacent beaches. In the past 130 years, the 

 east-facing beach south of Cape Henry accreted, while the east- 

 facing beach north of Cape Hatteras eroded (Figure 28) . Con- 

 currently, the north-facing beach west of Cape Henry eroded 

 and the south-facing beach west of Cape Hatteras accreted. The 

 net change is a very slight clockwise rotation and southward 

 movement of the cape boundaries. The eastward progradation of 

 Cape Henry and the southward progradation of Cape Hatteras are 

 similar to longer term geologic changes in these areas as re- 

 flected in the orientation of beach ridges (Figures 2 and 7) . 

 Erosion north of Cape Henry and north of Cape Hatteras does not 

 reflect past geologic changes; however, because these changes 

 have occurred for at least 130 years, they can be expected to 

 continue into the future. 



A divergent alongshore transport nodal zone, identified using 

 shoreline change data, exists near latitude 36°4l'. This ap- 

 pears to be the only site of net alongshore sediment transport 

 reversal along the east-facing ocean coast between Capes Henry 

 and Hatteras. 



Overwash probably has not been a major factor in producing 

 changes in the sound shoreline. Most of the retreat in the 

 sounds away from inlet influences can be accounted for by 

 considering sea level rise on a gently sloping shore. 



107 



