The Cape Charles terrace is characterized by numerous secondary 

 morphological features, among which linear shoals and semi-closed 

 depressions are most common. These linear features have been related 

 to the tidal current pattern by Ludwick (1970) . 



Tides in Chesapeake Bay Entrance are semidiurnal with a mean range 

 of around 3 feet and spring range of 3.5 feet. On the outer coast of 

 Virginia, adjacent to the Bay Entrance, mean and spring ranges are 

 about 3 and 4 feet respectively (U. S. Dept. of Commerce, 1971). 



Tidal currents in the Bay Entrance vary in velocity from place to 

 place, but are generally between 1 and 2 knots maximum on both flood 

 and ebb flow as measured at the surface. (U. S. Dept. of Commerce 

 1967, Haight, Fennegan and Anderson 1930, Haight 1942, Ludwick 1970.) 



Nontidal circulation in Chesapeake Bight (Cape Henlopen, Delaware 

 to Cape Hatteras) has been reported by Harrison et al (1967) from 

 drifter studies. Their study shows that bottom drifters set out on 

 the shelf at less than 40 n. miles offshore tend to drift shoreward and 

 that there is a pronounced tendency for seabed drifters to travel toward 

 and even enter Chesapeake Bay. 



Waves on the open coast south of Cape Henry as measured by the CERC 

 wave gage at Virginia Beach are less than 3 feet high more than 90 per- 

 cent of the time. Most of the Bay Entrance is open to easterly waves 

 from offshore and to waves generated within the lower Bay which may 

 reach heights of over 4 feet especially with northerly winds. 



2. Geologic Setting 



a. Regional Aspects 



The Chesapeake Bay study area lies within the Atlantic Coastal 

 Plain Province. Basement rock underlies the area at depths greater 

 than 2,000 feet (Ewing, et al, 1937, Cederstrom 1945, Richards 1967). 

 The basement is overlain by a succession of sediments and sedimentary 

 rocks of the Potomac group (Cretaceous) ; Pamunky group (Eocene) , 

 Chesapeake group (Miocene) and a variety of Pleistocene age deposits 

 collectively called the Columbia group (Cederstrom 1945) (Table 1) . 

 Recent deposits consisting largely of marine, estuarine and littoral 

 sand, silt and clay are confined to submerged and coastal portion of 

 the report area. 



Miocene beds - the oldest of those with direct pertinence to this 

 study - exceed 600 feet in thickness regionally and consist of layers 

 of sand , gravel, diatomite and shells (Cederstrom 1945, Sinnott and 

 Tibbitts 1954, 1957; Harrison et al, 1965; Richards 1967). The Miocene 

 section in southeastern Virginia is divided into four formations: the 



