stabilized by Ammophila breviligulata along the northeast coast. No adverse 

 impacts of this stabilization were identified. 



4. S ite Daecription . 



The Nauset Spit system developed from the deposition of material eroded 

 from the glacial cliffs of Eastham and Wellfleet and transported southward by 

 littoral currents. This barrier beach system, which consists of three spit 

 segments and two islands, was formed by spit elongation over the past 5,000 to 

 7,000 years. The spit system has continued to evolve and has migrated land- 

 ward, constantly reducing the overall dimensions of the enclosed bays. Nauset 

 Spit is dependent on the eroding headland (glacial) section of the outer cape 

 for its continued sediment supply. The shoreline position of the spit is 

 generally controlled by the erosion rate of these glacial bluffs since a 

 smooth contour of the outer cape has been maintained through time by wave and 

 current processes. 



The Nauset Spit system consists of three major parts: Naruset Spits — 

 Eastham and Orleans, North Beach, and Monomoy Island (Fig- 1). These sections 

 can be considered individually even though they have been historically con- 

 nected. Nauset Spits (Eastham and Orleans) and North Beach, which front 

 enclosed bays, are discussed in this study. 



Nauset Spits — Eastham and Orleans (Fig. 2) protect Nauset M»»rsh and serve 

 as the outer barrier for Nauset Harbor. The barrier consists of a double 

 spit, divided by Nauset Inlet. Prior to 1946, the south spit, Nauset Spit- 

 Orleans did not exist because Nauset Inlet was located against the glacial 

 headlands at Nauset Heights. Since that time, however, the spit has rapidly 

 grown northward with lateral inlet migration at the expense of Nauset Spit- 

 Eastham. This trend is occurring despite the long-term southward direction of 

 net littoral drift along this section of the Atlantic coast of Cape Cod. 



Nauset Harbor, a 547-hectare tidal lagoon, is a complex system with large 

 tidal hydraulic differences. The mean tidal range in the Atlantic Ocean 

 opposite the inlet is 2.1 meters; it is 1.3 meters just inside the inlet, 

 decreases to 0.7 meter at Nauset Bay (near the Nauset Coast Guard Station to 

 the north), and increases to 1.4 meters at the southern extremity of Town Cove 

 (U.S. Army Engineer Division, New England, 1969). Tidal currents through 

 Nauset Inlet have been measured at 6.5 kilometers per hour by Woods Hole 

 Oceanographic Institute scientists (D. Aubrey, personal coasmunicationj 1978), 

 and the existing inlet is hazardous to general navigation. The outline of the 

 large ebb tidal delta is clearly defined at low tide by breaking waves. The 

 shoals and inlet position shift seasonally, with major changes occurring during 

 coastal storms. 



North Beach (Fig. 3) is a 13-kilometer-long barrier spit that fronts 

 Pleasant Bay and Chatham Harbor (Fig. 1). This spit section has been 

 historically breached by migrating inlets at least three times; the earliest 

 recorded breach was marked by the sinking of the SparraU)~Hawk in 1626. The 

 term North Beach is confusing since sections of the spit are actually located 

 north of this segment. North Beach and South Beach were created when North 

 Beach was breached by an inlet in 1846. Sediment starvation by the downdrift- 

 migrating (southward) inlet resulted in rapid erosion of the south spit. This 

 report describes the cyclic phenomenon of inlet breaching and spit regenera- 

 tion (lengthening southward by littoral drift) and its pronounced effect on 

 both plant communities and barrier stratigraphy. 



23 



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