MORPHOLOGY OF COASTAL BARRIERS, DELAWARE, U.S.A.

John C. Kraft, Chacko J. John, Evelyn M. Maurmeyer

Abstract


The Atlantic Coast of Delaware consists of four separate but continuous segments including (from north to south): (1) a northward-projecting spit complex (Cape Henlopen); (2) eroding Pleistocene headlands; (3) a linear coastal washover barrier; and (4) an area of migrating inlets with associated modern and relict ebb and flood tidal deltas. Coastal process studies show that continuing coastal erosion is accompanied by longshore transport of sand eroded from headlands, offshore transport to the nearshore marine area, and overwash processes transporting sand landward across the barrier. Studies of the adjacent nearshore marine area show that the barrier and its various geomorphic elements lay at the outer edge of the continental shelf approximately 12,000 years ago, and migrated landward and upward to the present position as the Holocene marine transgression continued. The sequence of coastal sediments of the barrier system consist of (landward to seaward) tidal marsh fringe, lagoonal muds and sands, barrier sands (including washover, dune, and beach deposits), and shallow nearshore sand and gravel. Drill-hole studies provide information on the subsurface configuration of the barrier from which the three-dimensional structure and stratigraphy of coastal sedimentary environmental lithosomes may be defined.

Keywords


coastal barrier; Delaware; beach morphology

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