Beach zone of loose particles that covers part or all of a shore US has about 11000 miles of beaches 30 of shoreline Beaches form at calm spots between headlands shores sheltered by barrier islands Outer Banks ID: 261440
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Deposition of sediments outpaces erosion and forms sandy beaches. Beach: zone of loose particles that covers part or all of a shore.U.S. has about 11,000 miles of beaches (30% of shoreline).Beaches form at calm spots between headlands, shores sheltered by barrier islands (Outer Banks/Sandbridge), or places with moderate surf.
Depositional CoastsSlide2
Depositional CoastSlide3
Composition and Slope of BeachesBouldersCobblesPebbles
Gravel
Sand
Silt
Shells
CoralsGlass/Trash
Flatter the beach, the finer the grains.
Due to porosity.
Sandy beaches have low porosity so water easily washes in and out bringing equal amounts of sand in and backwashed back to sea.
Cobble beaches have high porosity and water sinks as it comes in. This deposits material but makes it difficult to bring material back out. Slide4
Beach and SlopeSandy Beach: Low Slope of 1 to 9 degrees
Cobble Beach: High slope of 9 to 24 degreesSlide5
Beach ShapeSlide6
Beach FeaturesBerm: Accumulation of sediment that runs parallel to shore and marks the normal limit of sand deposition by waves. (Usually have a steeper berm in summer and smaller or no berm in winter)Berm Crest: highest point on beach.
Backshore: Furthest part where beach is deposited.
Foreshore: Seaward of berm crest to the shoreline.
Beach Scarp: Vertical wall of variable height carved by waves at high tide.
Longshore
trough: Carved by waves and turbulent backwash.
Longshore
bars: Submerged or exposed accumulations of sand. Slide7Slide8
Longshore TransportLongshore Current: Form when waves approach the beach at an angle. Sand is moved by these currents forming sandbars and spits.
Often called
longshore
drift.
Along U.S. coast, this drift is from North to South because of storm systems in the north.