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Erosion & Deposition - Coggle Diagram
Erosion & Deposition
Problems Caused By Erosion
Water and wind erosion
are two
abiotic
processes that are
essential to life
on earth. They help to
release important chemicals into the environment to be used as nutrients.
Both kinds
of erosion
can cause problems
, though.
Soil erosion is a major problem for farmers
. When
farmers till
the
soil before
they
plant
their
crops
, it can
easily be washed away by the rain or blown off by the wind
.
Water erosion
can also
harm buildings
. Sometimes
statues made from rock
start to
dissolve
. This is
especially
a problem in
areas
that
have acid rain
. Acid rain happens when
chemicals from smoke stacks make rain become more acidic
.
Acids
are very
good at
dissolving and melting rocks.
The Shore
The
seashores diverse landforms
are c
onstantly changing.
A coast or shoreline is simply the place where land and a body of water meet.
Waves
play a major role of
building up and breaking down the shoreline.
The Earth’s
coastlines
are the scene of a
continual tug-of-war between sea and land
.
Erosion by Waves
Large waves
can
hit rock
s along the shore
with great force
.
This energy can break apart rocks.
Over time, waves can
make small cracks larger
. Eventually, the waves cause pieces of
rocks to break off
. The rocks are broken into smaller and smaller pieces that
eventually become sand
.
Waves
can also erode by
abrasion
. As a
wave approaches shallow water
, it
picks up sediment
, including
sand and gravel
. This
sediment is carried forward by the wave
. When the
wave hits land, the sediment wears away rock
like sandpaper wearing away wood.
When
waves crash on the beach head-on
, the
water moved through flows back to the ocean underneath new incoming waves
. The
movement of water
, which
carries sand and rock fragments away from the shore
, is
called undertow
.
Deposits by Waves
Waves
shape a coast when they
deposit sediment
,
forming features
such as beaches, spits, and barrier islands.
Waves carry a variety of materials
, including sand, rock fragments, dead coral, and shells.
As
water reaches the shore
, they
drop the sediment
they carry,
forming a beach
.
A beach is an area of wave-washed sediment along a coast.
The
movement of sand
along a beach
depends
on the
angle at which the wave strikes the shore
.
Most waves
approach
the beach
at a slight angle
instead of straight on. These angled waves
create a current
that runs
parallel to the coastline
.
This movement of water is called a longshore current.
A longshore current is a water current that
moves the sand down the beach after its been deposited.
As they transport sand, ocean waves, and currents shape a variety of coastal landforms.
The sand builds up to form sandbars.
A sandbar is a ridge of sand built up by the action of waves and currents.
A sandbar that has built up above the water’s surface
and is
joined to the land at one end is called a spit.
Strong longshore currents
that mostly
move in one direction
can
produce sandbars
that
build up
over time into barrier islands
.
Barrier islands constantly change shape.
Hurricanes and other storms can speed up this change. During
large storms
,
waves can surge across the land
,
carrying away huge amounts of sediment and depositing it elsewhere
. People have built homes and hotels on many of these barrier islands. But the storm waves that built up the beaches can also wash them away.
The color and texture of beaches vary.
They vary
because the type of material found on a beach
depends on its source. Light-colored sand is the most common beach material. Much of this sand
comes from
the
mineral quartz
. But not all beaches are made of light-colored sand.
A barrier island is a long, narrow island that develops parallel to a coast
. A barrier island gets its name from the fact that it forms a barrier between the ocean waves and the shore of the mainland.
As a barrier island builds up, grasses, bushes, and trees begin to grow on it.