5 minute check
November 6, 2013
What is the difference between a
constructive and a destructive force?
4.3 - The student will describe how landforms are the result of a combination of
constructive and destructive processes.

Destructive Forces: processes that destroy
landforms.
◦ 2 types: Slow (weathering) and Fast (Erosion)
◦ Ex. landslides, volcanic eruptions, earthquakes,
floods

Constructive forces: forces that build up an
existing landform or create a new one.
◦ Caused by: water, gravity, wind and glaciers.
◦ Ex: deposition, landslides, volcanic eruptions,
floods

Destructive forces – destroy and wear away landmasses through
processes like weathering and erosion.
◦ Weathering – wearing by wind, precipitation, freezing/thawing
◦ Erosion – wearing down & carrying away of land by natural forces



Destructive forces are those that are recycling the Earth, like
Earthquakes and plate movement.
One example is when wind erodes or takes away some of the sand
on a sand dune or beach.
Farming is a destructive process, because the soil has to be dug up
and moved around in order to grow plants. Mining is another
destructive process, because we dig holes into the earth or blow up
parts of the earth and/or caves in order to get what we want.
Weathering Pictures

Weathering: a slow, destructive force that
breaks rocks into smaller pieces called
sediments. Can be by a physical (mechanical)
or chemical process.
Mechanical weathering:
the breaking of rock into
smaller pieces by forces due
to gravity, ice, plant roots, or
other physical forces.
Grand Canyon Video

Erosion: the destructive movement of
materials away from one place by wind,
water, ice and gravity.
Wave Erosion- caused by water
Wind Erosion (Dust Storm)

Landslides: occur when gravity quickly pulls
rock and dirt downhill.

Floods: a great flow of water over an area
that is usually dry land.


Volcano: an opening
in the Earth’s crust
through which
steam, lava and
ashes erupt.
Cause both
destructive and
constructive changes
to landforms.
Mount St. Helens Video
Saint Helen’s Before
Saint Helen’s After
Volcanoes can be constructive, but also
destructive…

Earthquakes: the
shaking of Earth’s
surface caused by
the release of
energy along a
fault.
San Andreas Fault, California



Constructive forces – shape earth’s surface by
building up mountains, volcanoes and other
landmasses caused by plate movements. It makes
positive changes!
One example of a constructive process is when
sand is deposited onto a river bank by the running
water. This builds up the river bank, making it
higher.
Another example of a constructive process is a
volcano erupting. This builds up the land around
the volcano, making it higher.

Any type of geological event where land is
uplifted.
 Uplift- the movement of fault block
(normal fault)
 Mountain
of two plates
Building- the convergence

Deposition: the placing of
materials in a new place
(constructive force).

Ex. Sandbars

River DeltaDeposits of
sediment at the
mouth of the
Mississippi River
creating new land
called a delta.

Sand Dunes- sand is moved by wind
Desert Sand Dunes
Ocean Sand
Dunes
Grand Canyon – sandstone rock
New York – lichen on granite; secrete
chemicals that break down rock
The Bernard Glacier in
Alaska's Saint Elias Mountains
5 minute check
November 7, 2013
Give an example of a Constructive
and a Destructive force?
4.3 - The student will describe how landforms are the result
of a combination of constructive and destructive processes.

Destructive Forces: processes that destroy
landforms.
◦ 2 types: Slow (weathering) and Fast (Erosion)
◦ Ex. landslides, volcanic eruptions, earthquakes,
floods

Constructive forces: forces that build up an
existing landform or create a new one.
◦ Caused by: water, gravity, wind and glaciers.
◦ Ex: deposition, landslides, volcanic eruptions,
floods


Any type of geological process that destroys or moves land
Weathering- the process of breaking down rock into smaller pieces
◦ Chemical- acid rain breaks down rocks
Example: Granite gravestones and statues
◦ Mechanical- the use of mechanical force to break apart rocks
Example: plant growing in sidewalk


Any type of geological process that destroys or moves land
Erosion- the process of moving sediment
◦ Glacial Erosion- glaciers push rocks and move them downhill
Example: Alaska glaciers and alpine glaciers
◦ Wind Erosion- wind picks up and carries sediment
Example: moving sand dunes
◦ Gravity Erosion- gravity forces rocks and large landmasses downhill
Example: landslides

Constructive forces: forces that build up an
existing landform or create a new one.
◦ Caused by: water, gravity, wind and glaciers.
◦ Ex: deposition, landslides, volcanic eruptions,
floods
Nevada’s Great Basin National Park
A- Constructive
B-Destructive
pine tree eroded by wind
Nevada’s Great Basin National Park
A- Constructive
B-Destructive
pine tree eroded by wind
Lake Tahoe – created by a normal fault
A- Constructive
B-Destructive
Lake Tahoe – created by a normal fault
A- Constructive
B-Destructive
Sierra Nevada Mountains
A- Constructive
B-Destructive
Sierra Nevada Mountains
A- Constructive
B-Destructive
Spring Mountain Range (Mt. Charleston)
A- Constructive
B-Destructive
Spring Mountain Range (Mt. Charleston)
A- Constructive
B-Destructive
Red Rock Canyon
A- Constructive
B-Destructive
Red Rock Canyon
A- Constructive
B-Destructive
Valley of Fire
A- Constructive
B-Destructive
Valley of Fire
A- Constructive
B-Destructive
Grand Canyon
A- Constructive
B-Destructive
Grand Canyon
A- Constructive
B-Destructive
5 minute check
November 8, 2013
What are all the names for the hot stuff
that comes out of volcanos?
4.3 - The student will describe how landforms are the result of a combination
of constructive and destructive processes.