Examples of Erosion and Barrier Transgression on the U.S. East Coast

Roger N. Dubois
University of Maryland,
Baltimore County
Department of Geography
and Environmental Systems
1000 Hilltop Circle
Baltimore, MD 02120

Slide Show!
  1. Beach berm that was overtopped by the swash of Hurricane Gloria (October 1985). Swash has accumulated in the backshore. The beach is located in the Delaware Seashore State Park, just south of Dewey Beach, DE.


  2. During the winter along the Delaware coast, storm waves generated by northeasters erode the beach and construct a longshore bar, upon which a person is standing in this photo (April 1982).


  3. Foredune in the Delaware Seashore State Park. The elevation of the foredune varies from 3 to 4 m above mean sea level (September 1988).



  4. Foredune in the Delaware Seashore State Park. The elevation of the foredune has been reduced (see slide 3) by overwash. The irregular black beach surfaces are zones of heavy mineral concentrations (October 1991).


  5. The shoreline of Ocean City, Maryland, has been eroding at an average rate of about 1 m/yr. During the early 1980's, city officials thought that the real estate along the beach could be protected by building an artificial dune; a dune was constructed by bulldozing beach sediments. This activity reduced the volume of beach material which normally would have been available to absorb storm wave energy (April 1982).

  6. The shoreline of Ocean City, Maryland, has been eroding at an average rate of about 1 m/yr. During the early 1980's, city officials thought that the real estate along the beach could be protected by building an artificial dune (see slide 5). Storm waves badly eroded the artificial dune. To protect this area from further storm damage a different approach was initiated in the late 1980's. The beach has been artificially widened by dredging sediments from the continental shelf and pumping them onto the beach. This slide, taken in September 1988, was taken from about the same position as slide 5.

  7. Beach erosion has occurred along this beach segment of Cayo Costa Island, FL, as seen by the fallen palm trees resting on the beach (April 1969).


  8. A minor storm is attacking the seaward side of a berm during a high tide; the swash action is confined primarily to the seaward side of the berm (July 1979).



  9. A minor storm attacked the seaward side of this berm during high tide (see slide 8). When the tide fell, a ~30 cm high beach scarp appeared along this Delaware Beach (July 1979).



  10. The wind is blowing onshore from left to right in this slide. The interaction among wind, sand, and beach grass tufts has caused streamline features to form on this beach (Delaware). Sands have been eroded from the windward side of the tufts while deposition has occurred in the lee of the tufts where some dead grass have been blown over (August 1986).

  11. The wind is blowing onshore from right to left in this slide. This slide was taken at about the same location as slide 10. Interaction among wind, sand, and beach grass tufts has caused streamline features to form on this beach (Delaware).



  12. Looking south at Cape Hatteras from the upper deck of the Cape Hatteras Lighthouse (June 1980).




  13. Looking north along the shoreline of Assateague Island, Maryland. To the left of the barrier island is Sinepuxent Bay. The offset of the barrier in the upper part of the view is caused by the jetties at Ocean City Inlet, which trap the southerly flowing littoral drift. In response to a relative sea level rise of about 2 mm/yr. The barrier has been transgressing at an average rate of 1 m/yr. Storm overwash transport sediments from the seaward side of the barrier to the bay side (April 1982).

  14. Near Assateague Island, Maryland, we can see that some time in the past 100 years or so, a severe storm cut through the barrier to create an inlet and a flood tidal delta in the bay. The inlet has since closed by the delta and its main channel can still be seen. When the inlet was open, it provided an avenue by which sediments on the seaward side of the barrier could be effectively transported into the bay (April 1982).

  15. During barrier transgression, storm waves transport sediments from the seaward side to the bay side. In time the bay side vegetation may be covered by washover deposits. Eventually as the barrier continues to transgress, the bared vegetation is exposed along a foreshore following storm conditions. This view (March 1982) shows exposed peat and tree stumps (20 to 40 cm in height) at a beach in the Delaware Seashore State Park.

  16. This view (January 1983) was taken at the same location as slide 15 in the Delaware Seashore State Park. Peat and tree stumps along the Atlantic foreshore of Delaware are primarily exposed during the winter months when storm waves erode beach sediments and deposit them in the nearshore. During the summer months, when swells prevail, the sand berms reform and cover the peat and stumps.

  17. View of Ocean City Inlet, Maryland (April 1982). This inlet was cut during a hurricane in 1933. In order to stabilize the inlet for commercial fishing, jetties were built and completed in 1935. Because littoral drift flows southward (right to left), deposition has been extensive along a beach segment north of the jetties. South of the jetties, the north end of Assateague Island, which is in a Maryland State park, has been severely eroded.

  18. View of the Indian River Inlet located in the Delaware Seashore State Park (April 1982). The barrier shown is a bay mouth barrier. In this general area, inlets have opened and closed throughout the nineteenth and early twentieth century. To stabilize the inlet, jetties were built. The project was completed in 1939. In this view the littoral drift flows north (left to right) so that beach progradation has occurred south of the jetties while beach erosion has taken place north of the jetties. The eroding beach threatened the integrity of Delaware Highway 1, which is the only north-south road on the barrier. In the past sediments were dredged from the pond in the upper right of this view and piped to the eroding beach.

  19. View of a dredge used near the Indian River Inlet, Delaware Seashore State Park (May 1982). Erosion threatened the integrity of Delaware Highway 1, which is the only north-south road on the barrier (see slides 17 and 18). In the past sediments were dredged from a pond and piped to the eroding beach. The dredge used in this operation is shown here. Since 1990 a fixed plant sand-by-passing system located at the inlet has replaced the pond dredging operation.

  20. View of Cape May, NJ (April 1982). The littoral drift is from the north to the south (top to bottom). At the top of this view one can see the Cape May Inlet with jetties; deposition has occurred north of the jetties while erosion has taken place south of the jetties. Several groins line the shore of Cape May itself. The most southern groin is the largest and has trapped a great deal of sediment; south of this groin the beach has extensively eroded.

  21. Homes have been built very close to the Maryland and Delaware beaches. At South Bethany Beach, Delaware, single family homes are permitted to be built directly on the beach as shown in this slide taken at low tide (April 1984). A person is standing on exposed peat, which suggests that this barrier is transgressing.


  22. At South Bethany Beach, Delaware, single family homes are permitted to be built directly on the beach. Small to moderate northeasters usually do not cause major damage to these homes, but overwash does at times cause damage to the road that runs parallel and directly behind the homes (April 1984). In addition, water and sewer pipes that run under the road and to the homes have been exposed and are vulnerable to damage.

  23. View of the shore near Fenwick Island, Delaware (May 1982). Property owners have not been permitted to build on the beach or on the foredune in this area. Sand fences have been erected along the foredune to induce deposition and to keep people off the dunes.


  24. Condominiums and hotels have been built on the foredune while single family units have been built on bay marshes in this photo taken in Ocean City, Maryland (April 1982).



  25. Viewing north at sand waves along the Outer Banks near Whale Bone Junction, NC. The water body at the upper left of the barrier is Albemarle Sound. The sand body at the far north extent of the barrier is Jockey's Ridge (June 1981).

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