Transcript Erosion and deposition Erosion The process by which water, ice, wind or gravity moves fragments of rock and soil. What evidence of erosion do.

Erosion and deposition
Erosion
The process by which water, ice, wind or gravity
moves fragments of rock and soil.
What evidence of
erosion do you see in
this picture?
Deposition
• Deposition is a constructive process in which
sediment settles out of water or wind, or is
laid down, and creates new landforms.
Erosion is Movement of Sediment!
• This process, known as
Erosion, is gradually
wearing down the surface
of the earth.
• Erosion is the process by
which weathered rock and
soil (sediment) 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?
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
The 4 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 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.
Discussion
• What are some factors that affect the rate of
erosion?
– Weather, climate, the shape of land (topography),
and type of rock affect the rate of erosion.
• How are erosion and deposition related?
– When agents of erosion slow down, some
sediment can fall out of wind or water and be
deposited.
Challenge
• How can erosion affect the shape of sediment?
– As rock fragments are eroded, they bump against each
other, which can change the shape from poorly
rounded to well-rounded.
• How can erosion sort sediment?
– Sediment that is eroded over a short distance is
poorly sorted, with grains of different sizes. As
sediment erodes over a longer distance, it becomes
moderately sorted (with grains of a small range of
sizes) and then well-sorted (with grains of all about
the same size).