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CONSTRUCTIVE
AND
DESTRUCTIVE
FORCES
CONSTRUCTIVE FORCES
IDENTIFY SURFACE FEATURES CAUSED BY DESTRUCTIVE FORCES.
• Construct means to build up.
• Forces that build up features on the surface of the Earth.
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•
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Sediment (Deltas, sand dunes, etc.)
Volcanoes (makes Islands)
Tectonic Plates (Mountains)
Crust deformation (Folding or Faulting)
SEDIMENT
• The process of sediment being carried causes new
landforms.
• Wind – sand transported by the wind creates sand dunes.
• Water – bits of soil and rock can be carried downstream
and deposited causing deltas.
• Ice – glaciers pick up and move rock and other
materials, depositing it elsewhere.
WIND DEPOSITION
SAND DUNE CUMBERLAND ISLAND, GA
WATER DEPOSITION
SEDIMENT IS CARRIED BY RIVER
GLACIAL DEPOSITION
VOLCANO
• Volcanos can be both constructive and destructive
• https://www.youtube.com/watch?v=WgktM2luLok
• https://www.youtube.com/watch?v=8eO-7qm7fiY
VOLCANOES
• A volcano is an opening in the Earth's surface or crust,
which allows hot, molten rock, ash and gases to
escape from deep below the surface.
• Volcanic activity involving the extrusion of rock tends to
form mountains or features like mountains over a period
of time.
• Magma (inside)
• Lava (outside)
VOLCANOES
• There are two main types of volcanoes: shield
and composite.
• Shield volcanoes are usually found in the
middle of tectonic plates. Islands like Hawaii
are good examples of this type of volcano.
These are making new islands every
year…takes a long time. (Hawaiian Islands)
• There's a hole in the middle of the plate and
magma moves out and piles on top of itself,
slowly building a mountain of rock. (Katmai)
1. Magma reservoir
2. Country rock
3. Conduit (pipe)
4. Base
5. Sill
6. Branch pipe
7. Layers of ash emitted
by the volcano
8. Flank
9. Layers of lava emitted
by the volcano
10. Throat
11. Parasitic cone
12. Lava flow
13. Vent
14. Crater
15. Ash cloud
VOLCANOES
HOT SPOT
• https://www.classzone.com/books/earth_science/terc/
content/visualizations/es0904/es0904page01.cfm?chap
ter_no=visualization
TECTONIC PLATES
• Mountains can be formed because of moving tectonic
plates.
FAULTS
• Faults are cracks in the Earth’s crust.
• The surface of the Earth is made up of tectonic
plates that are floating on magma (molten
rock).
• It is along these fault lines that earthquakes and
volcanoes occur.
EROSION AND DEPOSITION
• https://www.youtube.com/watch?v=ChEHQUMEkX
w
• https://www.youtube.com/watch?v=g65_MgWaBo
M
DESTRUCTIVE FORCES
IDENTIFY EXAMPLES OF SURFACE FEATURES CAUSED BY DESTRUCTIVE
PROCESSES.
• Destruct means to destroy.
• Forces that destroy features on the Earth’s surface.
•
•
•
•
Erosion (water - rivers and oceans, wind)
Weathering (chemical or mechanical)
Impact of organisms
Earthquake
EARTHQUAKES
• An earthquake is a phenomenon that
results from the sudden release of stored
energy in the Earth’s crust.
• It is caused by a strain on the fault lines
of the Earth’s crust. When the energy of
the strain is released, similar to a rubber
band snapping, the earthquake occurs.
• At the Earth's surface, earthquakes
cause a shaking or displacement of the
ground and sometimes cause the
ground to break apart and change
shape. Earthquake Animation!
EARTHQUAKE
EARTHQUAKES
• More than buildings collapse
when an earthquake hits. The
land itself is totally changed.
You can see scars across the
landscape. Those scars appear
when one block of land has
moved compared to another.
Roads often change their
placement. They either
become uneven or just crack.
Streams can also change
course. Sometimes rocks can
fall and block the stream.
Other times, the land is even
lowered in certain areas. When
it's lower, it's easier for the
water to flow in the new
direction .
WEATHERING
AND
• Weathering is the breakdown of the continents and the land
around you. The breaking down of these rocks and land due
EROSION
to forces such as wind and water is weathering.
When it rains,
rocks are washed down a mountain or down a stream. Soils are
washed away. The ocean beats against a cliff and breaks it
apart. If it is moved elsewhere it is called erosion.
• Mechanical weathering is the
process of breaking big rocks
into little ones. This process
usually happens near the
surface of the planet.
Temperature also affects the
land. The cool nights and hot
days always cause things to
expand and contract. That
movement can cause rocks to
crack and break apart. Roots
and plants also push into the
rocks and break them apart.
They act like wedges and push
the rocks apart. Little animals
also help by burrowing and
digging through the ground.
MECHANICAL
WEATHERING
CHEMICAL WEATHERING
• Chemical weathering
includes the effect of
weathering on molecules
and atoms. As with all
chemistry, the greater the
surface area of an object,
the more chemical
reactions can take place.
For these chemical
reactions to happen in
nature, moisture, and
heat must be present.
BIOLOGICAL WEATHERING
• Biological weathering
would include the
effect of animals and
plants on the
landscape. This is
more than roots
digging in and
wedging rocks.
Biological weathering
is the actual
molecular breakdown
of minerals.
(IMPACT OF ORGANISMS)
TECHNOLOGY AND
HUMAN INTERVENTIONS
• Humans try to CONTROL these forces.
• seismological studies
• flood control (dams, levees, storm drain management,
etc.)
• beach reclamation (Georgia coastal islands)
STONE MOUNTAIN
FORMED BY PLATE TECTONICS
EMERSON FAULT
GORGE
PROVIDENCE CANYON, GA
APPALACHIAN MOUNTAINS
SAND MOUNTAIN
LIME SINKS-CHEMICAL
DISSOLUTION OF ROCKS
PINE MOUNTAIN
CHAIN ROCK AND KY FIRST
STATE PARK
CUMBERLAND FALLS
ONLY FALLS WITH
MOONBOW
BEACHES
BRASSTOWN BALD
HIGHEST NATURAL POINT IN
GA
BREVARD FAULT ZONE
CUMBERLAND PLATEAU
LOOKOUT MOUNTAIN
LAST BATTLE OF CHEROKEES
BLUE RIDGE MOUNTAINS
MISSISSIPPI RIVER
LARGEST DRAIN IN USA
Study Jams Landforms
Physical Geography – Forces that shaped our Earth
GeoAmerica: Mississippi Delta Blues
Study Jams – Weathering and Erosion