Transcript Erosion: The wearing away and movement of rock and soil which

Erosion
Day 1
• Define the word Erosion in your
own words.
Earth is Change!
• The rock that you pass on
the way to school each
day and the mountains
you see in the distance
may look like they've
been there forever, but
the truth is that they are
slowly disappearing.
• Each time it rains and
every time the wind
blows, tiny pieces of
sediment get taken
away.
Erosion is Change!
• This process, known as
Erosion, is gradually
wearing down the
surface of the earth.
• Erosion is the process
by which weathered rock
and soil are
moved from one place
to another.
• Erosion carves the
Earth's surface creating
canyons, gorges, and
even beaches.
What do you think has caused
this rock to look this way?
Rain causes Erosion
• When rain falls to the Earth it
can evaporate, sink into the
ground, or flow over the land
as Runoff.
• When it flows over land,
erosion occurs.
• Runoff picks up pieces of
rock and "runs" downhill
cutting tiny grooves (called
rills) into the land. How much
erosion takes place is
determined by the:
• amount of rainfall
• amount of plant growth
• shape of the land
• type of rock
Can you list 3 things that
effect runoff?
Can you explain what runoff
is?
Wind causes Erosion
• Wind erosion is a major problem on about 75
million acres of land in the United States.
• About 5 million acres are moderately to severely
damaged each year.
• Wind erosion physically removes from the field
the most fertile portion of the soil.
• Dust obscures visibility and pollutes the air and
water, causes automobile accidents, fouls
machinery, and imperils animal and human
health.
How do you think farmers feel about wind erosion?
Sand Causes Erosion
• The most active agent of
erosion with sand is
wind.
• As the wind blows it picks up
small particles of
sand/sediment and blasts
large rocks with the abrasive
particles, cutting and shaping
the rock.
• The ability for wind to erode
larger rocks is controlled by:
• Size of particles
• Speed of wind
• Length of time wind blows
• Resistance of rocks
Describe the circumstances in
which sand can cause the most
erosion.
Waves Cause Erosion
• Waves cause erosion by four different methods:
• Breaking – as the breaking waves hit the
shoreline, their force knocks off pieces of
existing rocks.
• Forcing water into the cracks of the rocks on the
shoreline
• Abrasion- waves carry small rocks and sand
that scrape other rocks
• Chemical weathering (salt water breaks down
the rocks)
• .
Compare and contrast chemical weathering to abrasion in wave erosion.
Waves Cause Erosion
• Factors that affect the rate of erosion at
the shoreline include:
• Size of the waves
• Force of the waves
• Type of the rock
Rain
Causes
Erosion
Wind
Causes
Erosion
Sand
Causes
Erosion
Waves
Cause
Erosion