Landforms

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Landforms

• 3.7B 4.7B 5.7B

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What are landforms?

• The natural shapes or features on the Earths
  surface are called landforms.
• Many different types of landforms can be found on
  the Earth.

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canyon
A canyon is a deep valley with very steep sides.
Rivers often flow through canyons.
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coastline
A coastline is the area where the ocean touches
the land.
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delta
A delta is a large, flat area of land where a
river flows into an ocean or sea.
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hill
A hill is a rounded area of land higher than the
area around it (not as high as a mountain).
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island
An island is land that is completely surrounded
by water.
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mountain
A mountain is a place on Earths surface that is
much higher than the land around it.
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sand dune
A sand dune is a hill of sand that is deposited
by the wind.
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valley
A valley is a long, low area of land that is
surrounded by higher land.
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True or False The Earths 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.
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True or False The Earths surface has stayed the
same for thousands of years
False
The Earths surface is CONSTANTLY changing!
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Landforms
Changing
Lets look at a large rock (called a sea arch) by
the seaside over a period of years.
The rock changed over this 80 year period. In
fact, it almost disappeared!
1970
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Landforms
Changing
What do you think caused these drastic changes in
the rock? What could possibly make rock break
down into smaller pieces?
1970
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Weathering and Erosion
Wind Water Ice Gravity
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Weathering

• The breakdown of the materials in the Earths
  crust into smaller pieces.

Weathering leads to the formation of new soil.
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Moving water can cause weathering.
What evidence of weathering do you see in this
picture?
Journal Jam 12
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Wind can cause weathering.
Why wasnt this mass of land weathered away?
What evidence of weathering do you see in this
picture?
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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.
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Plants CAN CAUSE weathering
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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?
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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
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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

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Evidence of Wind Erosion
Creates sand dunes
Greatest impact in deserts
Removes fertile topsoil
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Moving water causes erosion!
Creates MOST of the changes in the Earth's
landscape!
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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.

Rivers and streams are a constant flow of
runoff- they constantly weather and erode!
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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

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Moving ice causes erosion.
Glaciers wear down the landscape by picking up
and carrying debris that moves across the land
along with the ice.
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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!
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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

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Gravity causes erosion

• Landslides and Avalanches.

Slower
Faster
These are examples of mass movement (also called
landslides)
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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
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Plants CAN PREVENT erosion
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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
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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

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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 bygeologists. Some estimates
are between 6 and 8 million years, which is very
recent by comparison.
Canyons are large valleys created by a river or
stream.
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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. Wind builds up landforms
when it deposits sediments.
Sand dunes are hills of sand deposited by the
wind.
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Whats the evidence???

• What natural processes led to the formation of
  this landform? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the exposure of
  these tree roots? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  this landform? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  this landform? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  this landform? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  this landform? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  this landform? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  these cracks in the ground? What evidence can
  you give for this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  this landform? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  these cracks in the ground? What evidence can
  you give for this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  this landform? What evidence can you give for
  this conclusion?

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Whats the evidence???

• What natural processes led to the formation of
  this island? What evidence can you give for this
  conclusion?

Notice the evidence of the delta where the river
flows into the sea.
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Whats the evidence???

• What natural processes led to the destruction of
  this landform? What evidence can you give for
  this conclusion?