1 : 



Unvegetatsd 



Ammophila brevihgulola 



Artemisia 



slellerignq 



Euphorbia 



polygonifolla 



Lathyrus 



japonicus 



Soiiftago 



sempcrvirens 



Sparllno 



patens 



Sportina 



oltermflora 



Agropyron 



pun;«ns 



Mynca pt 



'Rsylvanica 



!00 pet COtfPr 

 50 



Figure 121. Vegetative-physiographic transect of belt H. 



Belt I has eroded rapidiy along the oceanfront, averaging 6.7 meters per 

 year between 1938 and 1978 (Table 54). This belt was reduced to less thar 

 one-half its original width (1938) by 1978. Two spit recurve remnants were 

 still evident in the area in 1978 (Fig. 122). The ocean dune .line, approxi- 

 mately 2.5 meters high and 80 iieters wide, was affected by sheet overwash 

 during the 1978 storm. Ammophila bveviligulata biomass on these dur.es "as 

 the second highest measured on the Nauset Spit system. (Tabic 55). The back- 

 barrier ridge, 2 meters high and 80 meters wide, was ao longer accreting. 

 Artemisia aaudata had invaded declining stands of Ammophila. brei'n.licfulata. A 

 broad shrub zone backed by a Spavtina patens grassland and a small inter tidal 

 pond were located in the center of the barrier. The seaward dunes at belt I 

 were very young, having been recently overwashed; the remainder of the belt 

 was between 40 and 80 years old. 



Belt D is located about 2 kilometers north of belt E in a very wide sec- 

 tion of Old North Beach (Fig. 90). In 18f-8 the dunes at belt D were badly 

 dissected by washovers, but there is no evidence that washover sediment was 

 added to the marsh surface (Fig. 114). Only a small breach in the dune line 

 was apparent by 1886. 



Aerial photos taken in 1938 show that belt D was part of a massive wash- 

 over that must have first occurred at least several years prior to this time. 

 Dunes were present at the bayward edge of the washover on substrate that had 

 been mapped as salt marsh in 1886. The isolated dunes in the interior of the 

 washover may have been cither remnant dunes present before the washover or new 

 dunes that developed from drift piles. 



Overwash continued at belt D in 1952. Several lobes of a massive wash- 

 over had expanded farther onto the salt-marsh surface, but did not reach the 

 bay because the barrier at this location was very wide. The rernant dunes 

 expanded, reducing the washover area. 



200 





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