The salt-marsh area decreased gradually between 1868 and 1952 (Table 47) . 

 Since 1952 total marsh area has increased by 12 percent; however, in 110 years 

 the total marsh area decreased by 29 percent. Some of this decrease may be 

 accounted for by the inability of Old North Beach to develop new salt marsh to 

 the lee of the barrier, since 37 percent of the back barrier abuts glacial 

 deposits (Fig. 90). Most of this marsh was lost to washovers (43 percent) and 

 dunes that developed on the washovers. 



There have been five major environments on Old North Beach in the past 110 

 years: dune, salt marsh, shrub, washover, and sandy beach. The only major 

 shrub communities on the Nauset Spit system are located on Old North Beach. 

 Shrubs were undoubtedly present on the spit before 1938, but were not indi- 

 cated on the U.S. Coast and Geodetic Survey (USCGS) maps. Dunes present in 1978 

 along the northern section of Old North Beach were the best developed for the 

 entire system. The dune line was continuous for up to 2000 meters, averaging 

 8 to 10 meters high and 200 meters wide. Salt marshes on Old North Beach were 

 also the best developed and widest on North Beach. In one area (site of 1626 

 inlet) the marsh is about 1000 meters wide. 



Dune area data collected from each map appear in Table 47. Dune and wash- 

 over environments were not differentiated on early maps. Although the com- 

 bined dune and washover area changed little between 1868 (194.3 hectares) and 

 1886 (is 1.7 hectares), 42.2 hectares eroded and 35.0 hectares of dune-washover 

 developed in new areas. Table 49 indicates that most of this loss was caused 

 by shoreline erosion along both the oceanside (58 percent) and along the bay 

 shore near the spit terminus (23 percent) . New dunes (and washovers) devel- 

 oped landward of the 1868 features, primarily on washovers (32 percent) and on 

 salt narshes that had been b^.ied by overwash (68 percent). 



Twelve percent of the salt-marsh loss between 1868 and 1978 was attributed 

 to bay-side erosion. Tidal currents behind Old North Beach do not generally 

 move large volumes of sediraent or erode cohesive salt-marsh peat. A total of 

 130.1 hectares of new salt marsh developed along the bay Fhore of Old North 

 Beach between 1868 and 1978. Most of these marches developed on old washovers 

 (51 percent) and by rhizome extension into shallow Pleasant Bay (30 percent). 



Shrub communities have rapidly expanded in the past 40 years en Old North 

 Beach. These communities develop on supratidal substrate that is protected 

 from salt spray behind continuous barrier dunes. A well-diversified shrub 

 community can develop in as little as 26 years on North Beach. One washover 

 created in 1952 supported several hectares of shrubs in 1978. Often shrubs 

 colonize washover termini, as dune vegetation stabilizes the boundaries of 

 the closing washover. With the termination of overwash and the development 

 of a continuous foredune line, low-lying areas in the back barrier dunes may 

 provide an environment for colonization by shrubs. 



The Old North Beach section of Nauset Spit has not been subject to inlet 

 dynamics within the past 110 years nor to very rapid shoreline erosion. While 

 the barrier has eroded mainly along the ocean shore, substrate has been placed 

 along the bay shore by overwash so that the barrier has lost little width 

 through time. Old North Beach will continue to migrate toward the glacial 

 deposits at Nauset Heights and at Big and Little Pochet Islands (Fig. 90), and 

 will narrow at these locations until the moraine is subject to wave attack. 

 Because Pleasant Bay is very shallow behind Old North Beach and the tidal 



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