To appear: Shore & Beach, Vol 72, No. 1, 2004.
dike and a series of fill projects conducted with sand dredged to keep the Fire
Island Inlet navigation channel open (Table 1). However, problems related to spit
formation at Democrat Point, shoaling within the inlet, and downdrift erosion
continue, requiring responses with dredged material placement.
Longer-Term Morphologic Evolution and Shoal Volume Changes
Historic records indicate that Fire Island has migrated westward since
construction of the Lighthouse in 1827.
Analysis by Leatherman and Allen
(1985) and Liu and Zarillo (1987) indicate that the westward migration of the
modern Fire Island Inlet is part of a much longer-term evolution of Fire Island that
includes reworking of the barrier system by several episodes of inlet breaching
and migration. The 1835 configuration of Fire Island Inlet shows a small inlet to
the west of what is now Captree Island and possibly the development of the
modern-day Oak Island as a flood shoal. Geomorphic details from the remainder
of the 19th century USC&GS T-sheets are incomplete, but the 1909 configuration
shows Cedar Beach to Oak Beach area as a fully integrated barrier system
(Figure 7).
Over the longer term, it is likely that Oak Island, Cedar Island,
Captree Island, and possibly other small islands, such as the Fire Islands to the
east in Great South Bay, were originally formed as flood shoals as inlets in the
vicinity opened and closed and Fire Island extended to the west.
The 1924 configuration shows a small inlet to the northwest of Fire Island
Inlet and the continued westward extension of Fire Island that overlapped the
Oak Beach area to the north (Figure 8). In 1924, the Fire Island Inlet cross-
section was apparently near equilibrium, but from 1924 to 1937, the inlet cross-
section decreased (Headland, et al. 1999). By 1937, the inlet had nearly shoaled
to the point of closure. From 1937 to about 1940 the inlet began to scour and
increase in depth and cross-section. Upon completion of the Democrat Point
Jetty in 1941, sediment transport across the inlet channel decreased. By 1950,
the jetty's compartment was full and sand began bypassing the jetty and
constricting the channel.
Since then the inlet again shoaled to near closure
(Figure 5) as the Democrat Point Jetty bypassed large volumes of sand. The
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