Waves
Section 9.5
Waves
• Waves form from wind that blows across
the surface of the water
• Particles of water move in a circular
pattern but the wave moves forward
• As a wave moves near land, the bottom
drags and the wave slows down. The
water moves forward and provides the
force that changes the shoreline
Erosion by waves
Impact – waves hit rock and break them
Abrasion – waves carry sediment that wears
away other rock
Headland – a part of the shore that changes
the direction of waves
Landforms
Sea cave – where waves erode softer rock
at the base of land
Landforms
Wave cut cliff – where rock collapses
because the base was hollowed out
Landforms
Sea arch – where waves erode softer rock under
harder rock. If the arch collapses a sea stack
could appear
Sea Arch
Sea Stack
Deposits
Beaches – an area of wave washed
sediment along a coast
Deposits
Longshore Drift – waves, that hit the shore
on an angle and run parallel to the shore,
carry sediment down the beach
Deposits
Spit – a beach that projects out into the
water as a result of a longshore current
Deposits
Sand Bar – long ridges of sand parallel to
the shore
Deposits
Barrier Beach – when waves pile sediment
up above sea level
Wind Erosion
Section 9.6
How Wind Causes Erosion
Wind is the weakest agent of erosion
It can be a powerful force in areas where
there are few plants
How Wind Causes Erosion
• Deflation – the process by which wind
removes surface materials.
• The stronger the wind, the larger the
particle that can be moved
How Wind Causes Erosion
• Abrasion – wind carried sand can polish
rock (sand blasting) but causes little
erosion.
Could have been caused
by weathering or water
erosion
Wind Deposition
• When wind slows down, sediment is
deposited
• Sand dunes and loess deposits are
formed by wind erosion and deposition
Sand Dunes
• Form when wind
strikes an obstacle
• Found on beaches
and in deserts
where sediment has
built up
Sand Dunes
Loess Deposits
• Fine sediment deposited far from its
source
• Found in central part of U.S.
• Helps to form fertile soil
Loess Deposits