Coastal Plain Physiography Topics

1. Regional Setting
2. General Physiography
3. Beaches and Shores
Sea Level Changes
4. Special Features
• Introduction to Physiography
• Coastal Plain
• Piedmont
• Mesozoic Basins
• Blue Ridge
• Valley and Ridge
• Appalachian Plateaus
• Virginia's Rivers


Beaches and Shores, Part 7

Environments (continued)


• Beaches are narrow strips of sediment (usually sand) deposited along shorelines between the permanent vegetation and low tide lines.

Beaches in Virginia’s Coastal Plain. Beaches act as buffers between the land and the sea. Left photograph is along the Chesapeake Bay on the Eastern Shore. The white structure in the background is an aircraft navigation station. Right photograph is of the Cape Henry area. (Left photo by G. Thomas; right photo by Robert Whisonant)

• Beaches are changing environments.  The beach type depends on grain size, sediment availability, water level, and wave activity.  When any of these factors changes, the beach will change too.

• Higher waves tend to erode sediment from the beach and shallow water and deposit it offshore.

• Shallow, gentler waves tend to move sediment toward the shore.

• Longshore currents can move sediment along the shore.  Where longshore currents move sediment in one direction, spits can form.

Aerial view looking down a typical spit.  Spits are long tongues of sediment attached to the coast.  Note sandy beach on higher energy ocean side and muddy, marshy sediments on lower-energy, bay side.  This spit is in Back Bay National Wildlife Refuge and False Cape State Park. (Photograph courtesy of the Virginia Institute of Marine Scienc)

• Where enough sediment is available, a line of dunes may form behind the beach on the shore.

Dunes are wind-formed hills or ridges of sand. In these coastal dune photographs, note the attempts to stabilize dunes with wind fence (left) and vegetation (right). (Left photo by Stan Johnson, right photo by Parvinder Sethi)

• Sand in dunes usually moves with the wind.  If storm waters reach dunes, sand can be eroded from the dunes and added to the beach system.

• During a storm, water can push through the dune line, carrying sand with it.  This process is called washover, and is responsible for much shoreline change.

• If a beach is on a barrier island or spit, washovers push sand toward the land.  This process causes the island or spit to move closer to the land.