PHYSIOGRAPHY OF THE VIRGINIA COASTAL PLAIN 



INTRODUCTORY. 



As has been previously stated, the Coastal Plain falls naturally into two 

 divisions, a submerged or submarine portion and an emerged or suuaerial 

 portion, the shore-line of the Atlantic Ocean forming the boundary between 

 them. This line of demarcation, although apparently fixed, is in reality very 

 changeable, for during the past geologic ages it has migrated back and 

 forth across the Coastal Plain, at one time occupying a position well over 

 on the Piedmont Plateau and at another far out to sea. At the present 

 time there is reason to believe that the shore-line is encroaching on the 

 land by a slow subsidence of the latter, but a few generations of men afford 

 a scarcely long enough period in which to determine this point definitely. 



SUBMARINE DIVISION. 



GENERAL CHARACTERISTICS. 



The submerged portion of the Coastal Plain may be described as a broad 

 plain with a very even surface sloping gently seaward beneath sea level. 

 In the vicinity of the edge of the continental shelf these characters are very 

 noticeable, but as the lan'd is approached the surface becomes decidedly 

 undulating. Small hills, which appear as shoalb, increase in number and in 

 size as the water becomes shallower until they finally rise above the water's 

 level. The slopes of these shoals are gentle and they are usually elliptical 

 in shape with the long diameter parallel to the shore-line. If contour lines 

 at intervals of one fathom should be drawn on the charts of the United 

 States Coast and Geodetic Survey along the eastern shores of Virginia, 

 they would be found to be roughly parallel to the shore-line, but there would 

 be frequent irregularities and many closed contours marking the small 

 submerged hillocks. Except near inlets where the tidal currents maintain 

 a deeper channel in the center and have produced numerous hooks and spits, 

 the one-fathom contour is a fairly constant line distant from the shore on 

 an average of from one-eighth to one-quarter of a mile. The two-fathom line 

 is about the same distance farther east while the succeeding lines for a 

 distance of several miles are considerably farther apart and only again come 

 nearer together as the edge of the continental shelf is approached. 



The material covering the submarine Coastal Plain near the shore is 

 primarily fine sand mixed with numerous broken shells, which furnish 



