A 5-meter-high tripod was initially set up over the coring site. A 20- 

 kilogram weight, raised by a rope and pulley system suspended from the tripod, 

 was used to drive the corer, a piece of polyvinyl chloride (PVC) pipe, 7 

 centimeters in diameter and 3 meters long, into the ground. After the PVC 

 pipe was pounded into the ground, a measurement was made from the top of the 

 core to the substrate surface to account for compaction. Water was then 

 poured into the rest of the pipe and an airtight plumber's plug was used in 

 the end to prevent the core from slipping out during extraction. Two 5-ton- 

 capacity truck jacks were hooked under a 7-centimeter metal collar that was 

 tightened 'round the outer perimeter of the coring pipe. The PVC pipe with 

 the enclosed core was then removed from the ground. 



The cores were taken to the laboratory for analysis. Core tubes were 

 split into lengthwise halves by a table saw. A piano wire was pulled along 

 the vertical length of the core to separate sandy layers, and a knife was used 

 to cut salt-marsh peat. The core was split into sediment samples based on 

 textural and mineralogical differences. The type of peat material (high or 

 low mar3h) was identified with a binocular microscope (Neiring and Warren, 

 1977), and organic materials were saved for radiocarbon dating. 



b. A nalysis of D ata. Correlation of a series of cores as a stratigraphic 

 section illustrates the long-term, landward migration of the spit. Figure 91 

 is a cross section constructed from cores taken at site 1 on Nauset Spit- 

 Eastham. Core C-l was taken in the middle of a narrow washover throat in the 

 dune line, and two cores (C-2 and C-3) were taken in the recently overwashed 

 salt marsh. An outcrop of peat {Spartina altevniftora) was present on the 

 beach during the survey period (Fig. 92). A second peat layer 60 centimeters 

 thick, dated at 815 years B.P. ± 95 years (University of Miami) and typed as 

 Spartina patens with lenses of Spartina alterniflor-a. v was found at the bottom 

 of a core C-l, more than 4 meters below the present surface. Above this 

 organic layer was an orange-white sandy section, characterized by coarse sandy 

 zones and heavy mineral laminations. This material was subaerially deposited 

 by overwash with evidence of some aeolian layers. The surface layers in cores 

 C-l and C-2 were recent washover deposits from the 1972 northeaster (Fig. 91). 



From these cores it was evident that a well-developed salt marsh existed 

 behind the barrier dune on Nauset Spit-Eastham as early as 815 years B.P. 

 Washover deposits burled the salt marsh sometime after this time, and dunes 

 subsequently formed In this location. The presence of peat also Indicated 

 that an inlet had not existed in this area within the past 800 years and the 

 dunes must ha"e formed on top of the washovers. 



A more detailed transect of cores was obtained froa North Beach, which 

 clearly shows the mechanism of the barrier retreat (Fig. 93). The coring 

 transect was again established through a recent washover throat to take advan- 

 tage of the low elevation surface In the dune field. One core was taken in 

 the back dune, and one was taken in the barrier grasslands. The salt-marsh 

 sediments were overlain by horizontally stratified washover deposits along 

 the entire coring transect. The marsh sediments of core NBI-2 were dated by 

 radiocarbon methods at 360 years B.P. ± 125 years (Geochron Laboratories) 

 at the base and less than 200 years B.P. (USGS) at the top. These dates 

 indicate a rapid rate of retreat for North Beach. Less than 300 to 400 years 

 ago, a salt marsh existed behind the barrier at this location on North Beach. 

 Salt marsh, which persisted for a few hundred years, was eventually killed by 



151 



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