Figure 3-12. Mound of slipper limpet shells, east of Mattituck Inlet, 21 November 2003
The area offshore east of the inlet lacks longshore sandbars and possesses a shoal,
displayed in Figure 3-13, oriented parallel to the shoreline. Its center line is located
approximately 1,600 ft offshore, and the shoal is approximately 2,100 ft long and 400 ft
wide at its center. The minimum water depth above the crest is 9.3 ft NAVD88. The
volume of the shoal is approximately 460,000 cu yd, measured from a reference datum of
21.5 ft NAVD88 (Chapter 4). The feature has an unusual rectangular shape that
contrasts with the more characteristic semi-circular or horseshoe shape of ebb shoals
found at many Atlantic Ocean inlets, including the south shore of Long Island. For this
and other reasons discussed in Chapter 6, the feature is not considered to be an ebb shoal.
Figure 3-14 displays elevation contours for the main longshore bar, the seaward
longshore bar adjacent to the west jetty tip, the bypassing bar adjacent to the east jetty,
and the offshore shoal. Collectively, these features comprise the sediment bypassing
complex for the area offshore of Mattituck Inlet.
Chapter 3 Field Data Collection and Analysis