. photographs and US Coast Survey maps were used to determine the changes in 

 shoreline position and major barrier environments during the past 122 years. 

 Earlier charts, maps, and accounts expanded these data back to the early 

 1600s, in a qualitative sense. Finally, cores and radiocarbon peat dates 

 were used to define the geologic evolution of the barrier system. 



Overwas h and Aeolian transport. During storms, the convex beach profile 

 is planed off by waves, while a large storm bar is constructed a short dis- 

 tance offshore. At high tide, swash may impinge directly on the seaward face 

 of barrier dunes. Low-profile areas, created by blowouts or vehicles, allow 

 swash penetration as overwash through the dune line. C/erwash Is defined as 

 the transport of seawater and associated sediment or d", if t from the beach face 

 to the back barrier. 



The most severe storm to affect Nauset during cho study period was the 

 1978 northeaster. The February 1978 northeaster may have been the most 

 significant extratropical s.torm to strike the Cape Cod shoreline in the last 

 50 to 100 years. This storm was estimated to have a deepwater wave height of 

 5 meters (m) and a probable return interval of 75 years. Nearshore breaker 

 heights approached 3 m and storm surge was approximately 1.2m. During the 

 storm, current meter measurements recorded maximum instantaneous velocities 

 of overwash surges up to 2. 44 m/sec. These surges were erosional and removed 

 most of the vegetation. As the overwash surges proceeded toward the inland 

 dune, they declined in velocity and became principally depositional at this 

 point. Large quantities of sediment were transported across the berta by 

 overwash surges and deposited in washover fans and flats. Volumetric deter- 

 minations showed that as much as 400 m 3 /m of overwash sand was transported 

 landward during this event, with penetration distances of 250 m bayward of 

 the dune line and deposition thicknesses up to 1.65 m above the living salt 

 marshes on the landward portions of the barrier. 



Although a substantial amount of sand is deposited during storm events, 

 much of this sediment is redistributed during interstorm periods. Tidal cur- 

 rents reworked the sand along fan margins, but in other areas wind has been 

 the principal means of redistributing the sediment. Prevailing northwest and 

 southwest offshore winds during the winter often exceed 30 knots per hour and 

 frequently average 10 to 15 knots per hour. Since this wind field is gener- 

 ated by Canadian high-pressure cells, strong winds are accompanied by clear 

 weather, resulting in maximum transport because the sand is dry. The 





