Movement of sand on the
beach…
is parallel to the shoreline
– Caused by wave refraction (bending)
– Each wave transports sand either upcoast or
downcoast
– Tons of sand are moved within the surf zone
– The beach resembles a “river of sand”
Longshore Current & Drift
Longshore Current
Zigzag movement of
water in the surf zone.
Longshore Drift
Movement of sediment
caused by longshore current.
Erosional Shoreline Features
• Headland
• Wave-cut
cliff
• Sea cave
• Sea arch
• Sea stack
Sea
Cave
Top of Sea Cave
w/ a Blowhole
Marble Sea Cave
Puerto Tranquila, Chile
Sea arch
Waves erode weaker rock,
but can’t reach the top.
Sea Stack
Collapse of sea arch
Puu Pehe (Sweetheart Rock)
Lanai, Hawaii
Depositional Shorelines Features
•
•
•
•
•
Spit
Bay barrier
Tombolo
Barrier island
Delta
Willoughby Spit, Norfolk
Hampton
Norfolk
Spit
A projection of a beach
into a body of water.
Tombolo
A land bridge made of
sand that connects an
island to the shore.
Barrier
Islands
Outer Banks, NC
Outer Banks after Hurricane Irene, 2011
Deltas
Triangle deposit of sediment from rivers
emptying into a larger body of water.
Mississippi Delta
Nile River Delta