between Oriental and Illinois Avenues (Fig. 3). The source of this dredged 

 material has been Absecon Inlet, just inside the Brigantine jetty (Fig. 4) 

 (Everts, DeWall, and Czerniak, 1974). 



A detailed discussion of civil works affecting the beaches on Absecon 

 Island is presented by U.S. Army Engineer District, Philadelphia (1974). 



3. Beach Material. 



New Jersey beaches consist mainly of medium- to fine-grained sand, com- 

 posed mostly of quartz. The Piedmont and Highlands of the Appalachian 

 Province provide the ultimate source of the beach sands. Presently, due to 

 the low terrain and gentle slopes of the Coastal Plain, the rivers draining 

 the higher areas become sluggish and deposit much of their sediment load along 

 the way before reaching the coast. What little sediment does reach the coast 

 becomes trapped in the lagoons behind the barrier islands, and never reaches 

 the beaches. The only natural sources of beach material now appear to be the 

 ocean floor and the beaches themselves. 



Ramsey and Galvin (1977) found the median grain size at Atlantic City to 

 be 0.27 millimeter (1.9 phi), with a sample range of 0.22 to 0.33 millimeter, 

 which agrees with the values obtained from surveys taken in 1936 and 1947 

 (Beach Erosion Board, 1950). They also determined that the grain size 

 decreased from the north to the south, the direction of net littoral trans- 

 port. This trend of decreasing grain size from north to south is shown in 

 Figure 5 which indicates the southward decrease in grain size across three 

 profiles at Atlantic City. A spatial trend in grain-size variation from the 

 berm to mean low water (MLW) is also indicated in Figure 6 for the sample 

 averages and in Figure 7 for the profile averages. These plots show an 

 increase in grain size from the berm to MSL, and then a slight decrease from 

 MSL to MLW. A seasonal grain-size variation shown in Figure 8 indicates that 

 the grain size increases from about 0.25 millimeter in October to 0.30 milli- 

 meter in December while decreasing from about 0.30 millimeter in December to 

 0.26 millimeter in March. This trend suggests an increase in the slope of a 

 stable foreshore from October to December when the sizes are increasing and a 

 decrease in foreshore slope when the grain sizes are decreasing from December 

 to March. 



No of Samples Averaged 



(83) 



(71) 



North on left ; not to scale 



I I 



2 4 6 



Profile Line and Relative Location 



Figure 5. 



Southward decrease in median grain size at Atlantic City; sample 

 averages are by profile line (from Ramsey and Galvin, 1977) . 



15 



