Weathering and Erosion

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Landforms
5.7B
What are landforms?
• The natural shapes or
features on the Earth’s
surface are called landforms.
• Many different types of
landforms can be found on
the Earth.
Journal Jam #1
canyon
A canyon is a
deep valley
with very steep
sides. Rivers
often flow
through
canyons.
Journal Jam #2
coastline
A coastline
is the area
where the
ocean
touches the
land.
Journal Jam #3
delta
A delta is a large, flat
area of land where a river
flows into an ocean or sea.
Journal Jam #4
hill
A hill is a
rounded area
of land higher
than the area
around it (not
as high as a
mountain).
Journal Jam #5
island
An island is
land that is
completely
surrounded
by water.
Journal Jam #6
mountain
A mountain is a
place on Earth’s
surface that is
much higher than
the land around
it.
Journal Jam #7
sand dune
A sand dune is a
hill of sand that
is deposited by
the wind.
Journal Jam #8
valley
A valley is a
long, low area of
land that is
surrounded by
higher land.
Journal Jam #9
True or False: The Earth’s
surface has stayed the same for
thousands of years.
Think about the statement in
the box above. Do you think it
is a true statement or a false
statement? Circle True or
False on Journal Jam #10.
True or False: The Earth’s surface
has stayed the same for thousands of
years
The Earth’s surface is
CONSTANTLY changing!
Changing
Landforms
Let’s look at a large rock (called a sea arch) by the seaside over a period of
years.
1890
1910
The rock changed
over this 80 year
period. In fact, it
almost
disappeared!
1920
1970
Changing
Landforms
What do you think
caused these
drastic changes in
the rock?
1890
What could
possibly make rock
break down into
smaller pieces?
1970
Weathering
The breakdown of the materials in the
Earth’s crust into smaller pieces.
Journal Jam #11
Moving water can cause
weathering.
What evidence of
weathering do you see
in this picture?
Journal Jam #12
Wind can cause weathering.
Why wasn’t this mass
of land weathered
away?
What evidence of
weathering do you see
in this picture?
Ice can cause weathering.
Water can get into cracks
in rocks. If the water
freezes, it can push the
sides of the crack farther
apart, making the crack
larger and larger.
Plants CAN CAUSE weathering
Journal Jam #13
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?
Erosion is the movement of
sediments!
• Erosion
gradually
wears down the surface
of the earth.
• Erosion carves the
Earth's surface creating
canyons, gorges, and
even beaches.
• Erosion is the process
by which weathered
rock and soil
(sediments) are
moved from one place
to another.
What do you think has caused
this rock to look this way?
Journal Jam #14
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:
• The amount of wind
• The speed of the wind
• The slope of the land
• The surface of the land
Evidence of Wind Erosion
Moving water causes erosion!
Moving 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.
Moving water causes erosion.
How much erosion
takes place is
determined by the:
• Amount of water
• Slope of the land
• Speed of the water
• Surface of the land
Moving 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!
Moving ice causes erosion.
How much erosion
takes place is
determined by
the:
• Size of the
glacier
• Slope of the land
• Speed of the
glacier
• Surface of the
land
Gravity causes erosion
Landslides and Avalanches.
Slower
Faster
These are examples of mass movement
(also called landslides)
Gravity causes Erosion
How much erosion takes
place is determined by
the:
• Amount of falling
debris
• Slope of the land
• Speed of the
falling debris
• Surface of the
land
Journal Jam #15
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
• Sand dunes
• Hills
Journal Jam #16
Deposition and erosion together
form deltas.
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
Weathering and erosion
together form canyons.
This simple animation provides
you with a visualization of how
the Colorado River has
"downcut" into the rock layers
of the Grand Canyon.
How long it took to carve the
Grand Canyon is debated by
geologists.
Canyons are large
valleys created by a
river or stream.
Some estimates are between 6
and 8 million years, which is
very recent by comparison.
Erosion and deposition together
form sand dunes.
Wind can move erode and
deposit sediments, especially
when it blows across open areas
with no vegetation.
Wind tears down landforms
when it erodes sediments.
Sand dunes are hills
of sand deposited by
the wind.
Wind builds up landforms when
it deposits sediments.
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