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Constructive and Destructive Forces

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Donna Green

on 28 January 2013

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Transcript of Constructive and Destructive Forces

Constructive and Destructive
Forces What Do You Think?
long-shore currents. Scientists know where earthquakes will occur because they know the locations of …
building of seawalls.
beach nourishment.
building of terraces. Beaches that have eroded are reclaimed through…
hot In which type of climate are you most likely to find a sand dune that is not on the coast?
the formation of a delta.
the carving of a valley.
the erosion of a beach.
the formation of a sea stack. A dam across a river can cause…
deposition at river mouths
erosion by rivers
weathering by wind
erosion by glaciers What causes V-shaped valleys to form?
Sea arches.
U-shaped valleys.
V-shaped valleys.
Desert pavement. A river can form …
They transport sediment.
They form cracks in the surface.
They release ash and lava.
They cause chemical weathering. How do earthquakes change the land?

A type of climate
The transport of sediment
The breakdown of rock
The aging of rock What is weathering?
a delta
a floodplain
a sand dune
a moraine What landform forms from deposition at the mouths of rivers?
Mud Volcanoes can create new land when they release…
Drumlins Long shore currents help create…
In desert areas
At river mouths
On the banks of rivers
In valleys formed by glaciers Where do deltas form? 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 Can Volcanoes and Earthquakes be Controlled? 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 Effects on the Control of Destructive 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 Effects on the Control of Constructive Forces Volcanic Activity
Movement of Earths Crust (Plate tectonics)
Reshaping of Mountains
Movement of Earths Crust (Plate tectonics)
cracks in the Earth Curst Other Destructive Forces Destructive Force
Examples of Erosion
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. How Can a Surface Feature be Changed by a Destructive Force? Constructive Force
Examples of Deposition
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 How Can a Surface Feature be Changed by a Constructive Force? Processes That Act Upon Earth’s Surface Features
the age of the volcano
earthquakes beneath the volcano
temperature of nearby rivers
the hardness of rock near the volcano Which of these do scientists use to predict when a volcano is likely to erupt?
planting vegetation
contour plowing
building windbreaks
building dams Which of these is not a way to prevent soil erosion?
breaks down rock physically
moves broken pieces of rock
changes rock chemically
change sediment into rock What does erosion do?
Long-shore currents
contour plowing Which of these helps prevent the harmful effects of erosion?
barrier islands
U-shaped valleys Deposition forms these features on coasts.
desert pavement
formation of U-shaped valleys
formation of rust
ice expanding in cracks in rock at is weathering? Which of these is caused by chemical weathering?
Volcanoes What forms moraines and drumlins?
Dissolves sediment
Breaks down rock to form sediment
Removes sediment from landforms
Drops sediment to form landforms Deposition is a process that… 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 Effects on the Control of 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? Controlling Constructive and Destructive Forces Other Constructive Forces Surface features are landforms and bodies of water that cover the Earth’s surface such as:

sand dunes
barrier Islands
moraines and drumlins
rivers What Are Surface Features? Destructive Force
A destructive force is a process that lowers or tears down the surface features of the Earth. Constructive Force
A constructive force is a process that raises or builds up the surface features of the Earth. What are Constructive and Destructive Forces? Chemical Weathering
Oxidation / rusting
Carbonic Acid / acid rain
Impact of organisms
Secretion of acid from Lichen 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 Changing the Earth’s Surface by a Destructive Force
Examples of Weathering
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