e5'>4e 



30'I0 



Contour Intervol 5 feet 

 up to 40, 2 feet thereofter 



Feet 



2000 4000 



(from Dietz, 1963, p. 984) 



Figure 4-24. 



Nearshore Bathymetry with Shore-Parallel 

 Contours off Panama City, Florida 



Bathymetry, such as that in Figures 4-24 and 4-25, suggests that the 

 depth to the deepest shore-parallel contour is usually constant along the 

 shore for distances of several miles, but that this depth may vary with 

 longshore distances of about 10 miles. (See Figure 4-25.) The depth to 

 the deepest shore-parallel contour may depend on the contour spacing, but 

 this is not important if contour intervals are small relative to the total 

 depths involved. In general, the deepest shore-parallel contour is between 

 15 and 60 feet. In most localities, this depth is somewhat deeper than 

 that at which nearshore profiles are presumed to close-out. These near- 

 shore contours probably reflect longer term adjustment to extreme storms 

 that occur rarely during the typical time interval between repetitive 

 nearshore profile surveys. 



b. Size Distribution . Geologic studies (Milliman, 1972; and Curray, 

 1965) suggest that littoral sands grade seaward into finer materials before 

 the relatively coarse sands of the shelf are reached. In some places the 

 boundary between the coarser shelf sediment and this finer material is quite 

 sharp. (Pilkey and Frankenberg, 1964.) The finer material is currently 



4-68 



