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What are Constructive and Destructive Forces?. Constructive Force A constructive force is a process that raises or builds up the surface features of the Earth. . Destructive ForceA destructive force is a process that lowers or tears down the surface features of the Earth. . What Are Surface Fe
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1. Constructive and Destructive Forces Processes That Act Upon Earth�s Surface Features
2. What are Constructive and Destructive Forces? Constructive Force
A constructive force is a process that raises or builds up the surface features of the Earth.
Destructive Force
A destructive force is a process that lowers or tears down the surface features of the Earth.
3. What Are Surface Features? Surface features are landforms and bodies of water that cover the Earth�s surface such as:
mountains
valleys
canyons
gorges
beaches
sand dunes
barrier Islands
flood-plains
moraines and drumlins
volcanoes
oceans
lakes
rivers
4. How Can a Surface Feature be Changed by a Constructive Force?
Natural forces such as wind, water, ice, through the process of deposition.
Deposition is the process of dumping sediment, dirt, rocks, or particles in one place.
The movement of the Earth�s crust through Plate Tectonics
5. Constructive ForceExamples of Deposition
6. Other Constructive Forces
7. How Can a Surface Feature be Changed by a Destructive Force?
Physical or Chemical Weathering
Weathering is the breaking down of rock into sediment.
Natural forces such as wind, water, ice, through the process of erosion.
Erosion is the movement of sediment from one place to another.
8. Changing the Earth�s Surface by a Destructive ForceExamples of Weathering Mechanical / Physical Weathering
Temperature Change-Freezing and thawing of Rock
Ice Wedging-Water freezing and expanding in cracks of rock
Impact of organisms
Root Pry
Animals burrowing
Chemical Weathering
Oxidation / rusting
Carbonic Acid / acid rain
Caverns
Impact of organisms
Secretion of acid from Lichen
9. Destructive ForceExamples of Erosion
10. Other Destructive Forces Volcanic Activity
Movement of Earths Crust (Plate tectonics)
Reshaping of Mountains
Earthquakes
Movement of Earths Crust (Plate tectonics)
Trenches
cracks in the Earth Curst
11. Visit these sites Land Formation
12. Controlling Constructive and Destructive Forces How can constructive and destructive forces be controlled through the use of technology?
How does technology affect constructive and destructive forces?
What are examples of technology used to control constructive and destructive forces?
13. Effects on the Control of Constructive Forces Dam � a structure built across a river to control its flow
Positive Effect
Flood Control
Hydroelectric Power
Negative Effect
Holds back sediment
Prevents deposition of flood plains, deltas, and beaches
14. Effects on the Control of Destructive Forces Prevention of beach erosion
Groin � a structure built perpendicular to the beach.
Positive Effect
Traps sand that moves along the shore and causing the beach to build up.
Negative Effect
Beach Erosion down stream is worse.
Seawall � a structure built parallel to the shore
Positive Effect
Protects land behind if from ocean the ocean waves
Negative Effect
Ocean side beach will erode
Beach Nourishment � sand from ocean or nearby rivers are pumped onto the beach
15. Effects on the Control of Destructive Forces Prevention of soil erosion
Contour Plowing � method in which farmers plow across the sided of hill instead of down
Terracing � the planting of corps on terraces (steps) built into steep hillsides.
Windbreaks � rows of plants or fences.
Slow down wind and limit the distance it can carry soil.
Vegetation � used to hold soil in place
Storm drain management � a system of drains
Prevents flooding and soil erosion
16. Can Volcanoes and Earthquakes be Controlled? Volcanoes and Earthquakes can not be controlled;
However scientist have ways to determine when and where these they might occur.
Volcanoes �
instruments are used to detect changes in volcanoes
Earthquakes �
Detailed maps show major faults
Safety Education
No new buildings on or near faults
Building codes to resists earthquakes
Seismographs � measures earthquakes on a rector scale
17. What Do You Think?
18. Deposition is a process that�
Dissolves sediment
Breaks down rock to form sediment
Removes sediment from landforms
Drops sediment to form landforms
19. Where do deltas form?
In desert areas
At river mouths
On the banks of rivers
In valleys formed by glaciers
20. Long shore currents help create�
Beaches
Dunes
Rivers
Drumlins
21. Volcanoes can create new land when they release�
Lava
Water
Faults
Mud
22. What forms moraines and drumlins?
Wind
Rivers
Glaciers
Volcanoes
23. What landform forms from deposition at the mouths of rivers?
a delta
a floodplain
a sand dune
a moraine
24. What is weathering?
A type of climate
The transport of sediment
The breakdown of rock
The aging of rock
25. Which of these is caused by chemical weathering?
desert pavement
formation of U-shaped valleys
formation of rust
ice expanding in cracks in rock at is weathering?
26. How do earthquakes change the land?
They transport sediment.
They form cracks in the surface.
They release ash and lava.
They cause chemical weathering.
27. A river can form �
Sea arches.
U-shaped valleys.
V-shaped valleys.
Desert pavement.
28. Deposition forms these features on coasts.
drumlins
floodplains
barrier islands
U-shaped valleys
29. What causes V-shaped valleys to form?
deposition at river mouths
erosion by rivers
weathering by wind
erosion by glaciers
30. A dam across a river can cause�
the formation of a delta.
the carving of a valley.
the erosion of a beach.
the formation of a sea stack.
31. Which of these helps prevent the harmful effects of erosion?
dams
volcanoes
Long-shore currents
contour plowing
32. In which type of climate are you most likely to find a sand dune that is not on the coast?
dry
humid
icy
hot
33. What does erosion do?
breaks down rock physically
moves broken pieces of rock
changes rock chemically
change sediment into rock
34. Beaches that have eroded are reclaimed through�
weathering.
building of seawalls.
beach nourishment.
building of terraces.
35. Which of these is not a way to prevent soil erosion?
planting vegetation
contour plowing
building windbreaks
building dams
36. Scientists know where earthquakes will occur because they know the locations of �
faults
volcanoes
mountains
long-shore currents.
37. Which of these do scientists use to predict when a volcano is likely to erupt?
the age of the volcano
earthquakes beneath the volcano
temperature of nearby rivers
the hardness of rock near the volcano