out 1 foot every 100 years (Westgate, 1983, p. 105); moreover, in New Jersey, sea levels are up 17 inches since 1900, and the rate of rise seems to be accelerating (Bennett, 1993, p. 132).
Even small changes in sea level may have catastrophic consequences for coastal environments. On Long Island, topographical features are generally of low relief and gentle slope. Such geomorphology renders the island vulnerable to marine effects. According to the Bruun theory, rising sea levels cause erosion when they remove upper beach material and deposited it on nearshore bottoms. This process displaces the beach profile shoreward (Schwartz, 1967, p. 76).
Additional factors which may affect shore lines include the following: coastal structures, storm activity, and sediment starvation. Commercial development can significantly alter a barrier island (Gorman & Reed, 1989, p. 122). For example, sometimes structures are built in front of the dune line. Such development may not only be adversely affected by advancing storms, it can also possibly alter an island's equilibrium between sediment deposition and erosion.
Perhaps the most potent force for modifying shore lines though, is the energy imparted by storm waves. A summer wave 10 feet tall and 100 feet long can exert a force of 1,600 pounds per square foot of coast line. In contrast, the force of a winter storm wave may exceed that pressure by four times (Page, 1987, p. 57). Winter waves tend to transport sand from the beach face to submerged sand bars off shore (Thom & Hall, 1991, p. 125). In addition, overwash surges (i.e., uprush that crests the most landward berm) can deposit considerable quantities of material onto barrier island flats (Leatherman et al., 1977, p. 119). Furthermore, a series of winter storms can be as devastating to coastal en
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