Download Erosion PPT

The Earth’s surface changes over
time due to weathering and erosion.
The Earth’s surface is always
changing!
Weathering
The breakdown do the materials of Earth’s
crust into smaller pieces.
Water causes weathering
What evidence of
weathering do you see
in this picture?
Ice causes weathering
Describe how ice
causes weathering?
Temperature changes cause
weathering.
Why did the outer layer
of the rock crack?
Erosion
The process by which water, ice, wind or gravity
moves fragments of weathered rock and soil.
Where did the forces of
erosion remove
material?
Erosion is Movement of
Sediment!
• The process known as
Erosion is gradually
wearing down the surface
of the earth.
• Erosion moves
weathered rock and soil
(sediment) from one
place to another.
• Erosion carves the
Earth's surface creating
canyons, gorges, and
even beaches.
• Erosion also acts below
the surface creating
caves.
Which force of erosion
carved this feature?
Be specific!
Wind Erosion
• 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 intensity of wind erosion
is determined by:
–
–
–
–
Sum (amount)
Speed
Slope
Surface
Wind Erosion
Water Causes Erosion
• runoff, rivers and, streams
Water 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.
Water causes Erosion
How much erosion
takes place is
determined by the:
–
–
–
–
Sum (amount)
Slope
Speed
Surface
Can you act increasing
and decreasing the
four S’s?
Ice Causes Erosion
Glaciers wear down the
landscape; by picking up and
carrying debris that moves
across the land along with
the ice.
Ice Causes Erosion
Glaciers can pick up and carry sediment that ranges in size
from sand grains to boulders bigger than houses.
Moving like a conveyor belt and a bulldozer, a single
glacier can move millions of tons of material!
Ice Causes Erosion
How much erosion
takes place is
determined by
the:
• **Sum (Glaciers are
massive!)
• Slope
• Speed
• Surface
Gravity causes erosion
Creep, Slump, Landslides, Mudslides, and Avalanches.
Slower
Faster
These are examples of mass movement
landslide clip.mpeg
(or called mass wasting)
Gravity causes Erosion
How much erosion takes
place is determined by
the:
•
•
•
•
Sum
**Slope
Speed
**Surface
Plants CAN CAUSE weathering
Plants CAN PREVENT erosion
Deposition
Rock particles that are picked up and transported
during erosion will ultimately be deposited
somewhere else
Deposition is the process by which sediments (small
particles of rock) are laid down in new locations.
• Together, Erosion and Deposition build new
landforms.
• Deltas
• Canyons
• Meanders
• Floodplains
Delta
Where rivers meet the
ocean is called the
mouth of the river.
Soil and dirt carried
by these rivers is
deposited at the
mouth, and new land
is formed. The new,
soil-rich land is known
as a Delta
Canyons
This simple animation provides
you with a visualization of how the
Colorado River has "downcut"
into the rock layers of the Grand
Canyon.
Canyons are large
valleys created by a
river or stream.
How long it took to carve the
Grand Canyon is debated by
geologists.
Some estimates are between 6
and 8
million years, which is very recent
by comparison.
Meanders
Meandering streams wander side to side as they
constantly seek out the lowest elevation.
This constant motion creates a series of S-shaped
“loops”.
Meanders
Stream Velocity varies from one side to the other side
of the “S”, resulting in erosion in some places and
deposition of sediments in others.
Floodplains
• Floodplains form along
the banks of mid-order
streams and larger rivers.
• These are low-lying
areas along the sides of
a river channel that have
regular times of heavy
waterflow to cause the
river to spill over and
flood the land.