VEGETATIVE STUDY AT THE DUCK FIELD RESEARCH FACILITY, 

 DUCK, NORTH CAROLINA 



by 



Gevald F. Levy 



I, INTRODUCTION 



1, General „ 



The Duck Field Research Facility is located on the Outer Banks of 

 North Carolina, a series of offshore sandbars extending from the Virginia- 

 North Carolina border southward about 200 miles to Bogue Inlet, North 

 Carolina, These bars lie almost parallel to the mainland and are 

 separated from it by shallow sounds of varying widths. 



The study area is included in Currituck Bank (North Bank) , which 

 extends from the Virginia-North Carolina boundary southward to the town 

 of Nags Head, a distance of about 45 miles (Fig. 1) . The bank was 

 originally demarcated by two inlets; Old Currituck Inlet, which was 

 located just south of the Virginia-North Carolina line until it closed 

 around 1730, and Nags Head Inlet, which was located just south of the 

 present town of Nags Head until it closed sometime between 1780 and 1810 

 (Stick, 1958). 



2. Origin . 



Most investigators cite a theory developed by Johnson (1919) for 

 the origin of this barrier island system. Johnson postulated that on a 

 gradually shallowing sea bottom, "...small waves break at the initial 

 shoreline and excavate a marine cliff and beach while large waves break 

 further out and proceed to excavate the same forms in the offshore 

 bottom." Excavated material was deposited landward of the breaking 

 waves, eventually forming a submarine bar of significant height and 

 indefinite length. Continuing growth irregularly raised the bar above 

 water, forming a chain of islands separated by inlets. 



The longshore current causes both shifting and closing of inlets. 

 Deposition on one side of an inlet is succeeded by erosion on the other 

 side, producing inlet migration. If deposition exceeds erosion the 

 inlets eventually close unless tidal currents and outflowing fresh- 

 waters are sufficient to dominate shoaling (Johnson, 1919) . 



Stick (1958) cited testimony from inhabitants which suggests that 

 hurricane winds raise the water level in the sound several feet above 

 normal. After storm passage, winds shift to the southwest and force the 

 impounded waters back over the banks, sometimes forming inlets. 



