(3) North remnant linear shoal - was present before the inlet formed just
behind Nauset Spit that became part of the north spit as it migrated
into the harbor.
(4) South remnant sand flat - present before the inlet opened and is now
incorporated into the land bridge to South Beach.
As the inlet has evolved over the past 13 years, the eight inlet sand features
have undergone an extensive modification. Area change has been updated from
the first study, based on a analysis of this continuing morphologic evolution since
the inlet breach formed. The eight shoal and adjacent spit areas of the original
study have been modified to reflect the evolutionary processes that have occurred
to the sand features. The present major morphologic features and channel orien-
tations are different from the initial inlet and are identified as follows:
a. Oceanside.
(1) Ebb tidal shoal/swash platform complex - now evolved into a south-
ward asymmetric multiple sand body separated by two ebb channels.
A smaller north swash platform is reforming north of the new north
ebb channel. A central swash platform is located between the two
channels and contains multiple swash bars. The southern part of the
ebb shoal now extends south of South Beach and contains a complex
pattern of swash bars.
(2) North spit on Nauset Spit - has now migrated westward into
Chatham Harbor and recently moved back to the south after initial
northward movement. The spit has grown in area and has several
recurved parts extending into Chatham Harbor.
(3) South spit/South Beach land bridge - spit has now welded to the
mainland beach, closing off southern Chatham Harbor and present-
ing a low, overwash dominated land bridge to the north tip of the
South Beach barrier island.
b. Bayside.
(1) South flood shoal - the south flood shoal evolved as the south spit
recurved back into southern Chatham Harbor. As the spit grew, it
gradually overtook the south flood shoal and is now incorporated in
the South Beach land bridge.
(2) Remnant south sand flat - as the southern flood shoal progressed
south into Chatham Harbor it overtook the remnant sand flat which
is now incorporated into the South Beach land bridge.
(3) Tern Island - existed before the inlet and has eroded from the south
and sand flats accreted on the north as the inlet has evolved. Other
sand flats north of Tern Island have also expanded greatly as sand
moves up from the south.
(4) Tern Island south shoal - originally an intertidal shoal on the south
side of the entrance channel to the Fish Pier, has now been eroded
away as the north flood shoal and west flood channel/new entrance
channel have evolved.
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Chapter 4 Ebb and Flood Shoal Evolution
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