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10.1
Shoreline Erosion
and
Deposition
Where does sand come from?
Sand
• Rock broken down into smaller pieces.
Shoreline
•The place where land and a body of water
meet.
Erosion
Wave Energy
• Waves – when wind
moves across the
ocean making a
disturbance.
Wave Trains
• Waves that move
•
•
in groups.
Wave period – the
period of time
waves in the wave
train are
separated.
Surf – Breaking
waves
The Pounding Surf
• Energy of the waves
•
•
crashing break rock.
Broken rock is thrown
to shore creating
sand.
Waves pick up the
sand and break down
pieces even smaller.
How do waves break rocks?
Energy is released by crashing
waves. This energy breaks rocks.
Water form breaking waves also
rushes into cracks in rocks, which
helps break rock and washes
away fine grains of sand.
• Sea cliffs – waves
Wave Erosion
erode and undercut
rock to make steep
slope.
Sea stacks –
offshore columns
of resistant rock
that were once
connected to the
mainland.
Sea Arches –
wave action
erodes sea
caves until
arches are cut
through the
caves.
Sea Caveswaves cut
large holes
into
fractured or
weak rock
along the
base of sea
cliffs.
Waves
Explain why large waves are more able to
remove large chunks of rock form a
shoreline than average-sized waves are.
Large waves are more able to remove
large chunks of rock from a shoreline
than average-sized waves are because
large waves transfer more energy than
average-sized waves do.
Beach
• Any area of shoreline
that is made up of
material deposited by
waves.
Shore Current
• Undertow – the
movement of water
carries pieces of sand
and rock away from
the shore.
Longshore current
• The current where water travels parallel to the
•
shoreline very near shore.
Waves hit the shore at an angle.
How do longshore currents move sand?
Waves break at oblique angles to the
shore. Waves wash sand parallel to the
direction they break. Return water flow
brings sand directly down the slope of the
beach. This process results in a zigzag
pattern of sand movement.
Offshore Deposits
• Materials are transported off shore.
Sandbar
An
underwater
or exposed
ridge of
sand, gravel,
or shell
material.
Barrier spit
An exposed sandbar that is
connected to the shoreline.
Barrier island
A long, narrow island usually made of
sand that forms parallel to the shoreline
a shore distance offshore.
Review Questions
1. How do wave deposits affect a shoreline?
2.
Wave deposits often form beaches along
shorelines.
Describe how sand moves along a beach.
Because waves strike shorelines at an angle,
sand moves along beaches in zigzag patterns.
3. How can the energy of water waves affect a
shoreline?
The energy from water waves can erode a
shoreline