salt marsh developed on the bay side (55 percent) and on washovers (44 per- 

 cent) that were Initially colonized by dune vegetation that failed to survive 

 because the washover elevations were only marginally supratidal. 



From these data, it is evident that Nauset Spit-Eastham has decreased 

 dramatically in size over 122 years. The southern 2.1 kilometers of the spit 

 has been lost to inlet miration; the northern 2.8 kilometers has remained an 

 unbroken unit, but has not maintained barrier width. Nauset Spit-Eastham is 

 eroding at a rate of 1.2 meters per year, approximately twice the rate of 

 cliff retreat north of the spit. This erosion rate appears to be discrete 

 rather than continuous. Very slow erosion occurred between 1856 and 1886, 

 while very rapid erosion resulted from one storin in 1978. Inlet dynamics 

 are the major process dominating the southern part of the spit, and overwash 

 is the dominant process in the northern part. During the period under con- 

 sideration, overwash has only been important in the redistribution of barrier 

 environments and not in the maintenance of carrier width. 



d. Old North Beach. During the past 110 years, Old North B<:ach has not 

 been affected by inlet dynamics. This region is delimited to the south by the 

 location of the 1868 inlet and to the north by Nauset Heights at the southern 

 end of Nauset Harbor (Figs. 3 and 104). The original breach through North 

 Beach in 1846 occurred just south of belt F (Fig. 90), which was 2.4 kilo- 

 meters north of the spit terminus in 1868. The 1626 inlet was approximately 

 8 kilometers from the southern end of the spit in 1868. Remnants of the inlet 

 channel are not evident today because the barrier has migrated to a position 

 landward of these features. 



Shoreline changes along Old North Beach during the past 110 years have 

 varied from erosion of 2.2 meters per year in the center of the section to 

 accretion by as much as 0.4 meter per year at the spit ends. Erosion rates 

 for Old North Beach averaged l.j meters per year between 1868 and 1978 (Table 

 42; Fig. 105). Marindin (1889) calculated the erosion of North Beach at a 

 rate of 2.4 meters per year during this same period (Table 40). This calcula- 

 tion is an average rate for North Ueach and includes the island south of the 

 1868 inlet, which eroded at rates of more than 20 meters per year. 



Since 1886 Old North Beach has consistently eroded landward. The greatest 

 retreat occurred between 1938 and 1952 when an average of 2.7 meters of shore- 

 line was lost per year. Between 1938 and 1978, erosion averaged 1.8 meters 

 per year, which correlates well with Gatto's (1979) rates of 2.0 and 0.9 

 meter per year between 1938 and 1974 for two locations along this section 

 (Table 40). 



During the past 110 years, an average of 165 meters of shoreline was lost 

 along Old North Beach, but the total area decreased only 6 percent from 450.2 

 hectares in 1868 to 421.5 hectares in 1978 (Table 47). Along the oceanside, 

 184.5 hectares was eroded; 62.9 hectares was lost from areas along the bay 

 side as a result of tidal currents eroding salt marshes and washovers (Table 

 48). The average barrier width was reduced only slightly during this same 

 time period (Table 43). In 1868 the width of Old North Beach averaged 446 

 meters; after 110 years, the same section had narrowed only 50 meters. The 

 widest point of Old North Beach decreased in width from 1196 meters to 997 

 meters as a result of shoreline erosion without commensurate expansion on the 



173 



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