transported (a) across the island by overwash or wind or (b) through inlet 

 openings directly to the sound shoreline. 



93. A general indication of island behavior is shown in Table 13 for 

 three regions (i.e., north and south of Oregon Inlet and west of Cape Hat- 

 teras) in the study area. Note that island narrowing, by portion of the 

 coast, is the most common change, while island widening is the least common 

 behavior. Slightly more segments of the island system moved seaward than 

 landward. Table 13 references direction of movement by 1-minute latitude or 

 longitude increments. The following four changes are noteworthy: 



a. For the measured segments, island narrowing greatly exceeded 

 island widening when averaged for the 130-year study period. 

 However, during the 1852-1917 period, island widening and nar- 

 rowing were almost equal. Between 1946 and 1980, three times 

 as much of the measured island system narrowed as widened. 



b. Island-narrowing-to-widening ratios were generally similar 

 north and south of Oregon Inlet. This suggests that the con- 

 ditions which led to the island width changes, while they 

 varied through time, were consistent throughout the study area. 



c. Over the study period, the island axis moved seaward at slightly 

 more places than it moved landward. This situation, however, 

 varied by survey period. Between 1852 and 1917 seaward move- 

 ment prevailed, while between 1946 and 1980 landward movement 



of the axis prevailed. 



d. For the measured portions of the study area, trends in island 

 narrowing or widening did not indicate particular movements of 

 the island axis. 



94. Figures 47-50 show the rates of island width change and the rates 

 of change in position of the island axis for different time periods. Fig- 

 ures 48 and 50 are limited to the section between Kitty Hawk and Cape Hatteras, 

 North Carolina, because that is the only area in which data were available for 

 both the periods 1852-1917 and 1917-1980. These figures illustrate the fol- 

 lowing alongshore changes in island width and position through time: 



a. The largest island width changes occurred near Back Bay, Vir- 

 ginia (Figure 47). This is an area of large ocean (Figure 28) 

 and sound (Figure 34) shoreline retreats. 



b. Increases in island width between Kitty Hawk and Oregon Inlet 

 (Figure 47) came as a result of progradation of the sound 

 shoreline (Figure 34) during a period of ocean shore retreat 

 (Figure 28) (the area near Croatan Shores was not influenced 

 by an inlet during the study period). The south-facing ocean 

 coast west of Cape Hatteras was also an area of island width 

 increase; however, here the increase occurred because of ocean 

 shore progradation (Figure 28). 



86 



