The%20state%20of%20Georgia%20wants%20you%20to

1
The state of Georgia wants you to

• Identify surface features caused by constructive
  and deconstructive processes.

2
Constructive vs. Destructive

• Land forms are the result of a combination of
  constructive and destructive forces. Constructive
  forces affect the earth's surface by building it
  up to form new landforms like mountains and
  islands. Destructive forces affect the earth's
  surface by breaking down landforms to form new
  ones.

3
Deposition deltas sand dunes

• The dunes are the product of the wind and rain
  eroding nearby mountains. The dunes collect here
  because the prevailing winds across the valley
  blow in this direction and meet winds blowing in
  the opposite direction. The sand drops to the
  valley floor and begins to collect. So over the
  course of millennia, the dunes have build.
  Tomorrow they will be different because the wind
  still blows, the sand still moves and the
  deposits of sand still grow.

4
Western Sand Dune
5
Delta

• A delta is a low, watery land formed at the mouth
  of a river. It is formed from the silt, sand and
  small rocks that flow downstream in the river and
  are deposited in the delta.
• A delta is often (but not always) shaped like a
  triangle (hence its name, delta, a Greek letter
  that is shaped like a triangle).

6
(No Transcript)
7

• NASA view of a delta from space.

8
Faults

• Faults are usually caused by the Earth's crust
  bending and breaking in the middle because of the
  forces pressing on it. These bends and breaks can
  form faults where the earth's crust is able to
  move. 
• Faults also mark plate boundaries. There are
  three main types of faults and each are
  constructive in their own way.

9
Divergent Fault Line

• Divergent Fault is where two plates are moving
  away from each other. (For more)
• As plates pull apart from each other the earth's
  crust spreads apart. This usually causes rifts or
  rift valleys. The majority of this activity takes
  place deep within the oceans along plate
  boundaries. As the plates pull apart hot magma is
  pushed toward the surface and volcanoes occur.
  This affects the Earth's surface by adding new
  material to the surface.

10
Convergent Fault Line

• Convergent Fault is when two plates come
  together.
• Not only can this cause destruction it can also
  cause construction. When two plates collide in a
  collision zone the result is mountains. The
  pressure of these two plates hitting each other
  causes the crust of the earth to rise. This can
  occur in the oceans of the world and on land.
  Mountain building is a very slow process but it
  is caused by convergent faults.

11
Transform Fault is when two plates slide past
each other.

• Notice how the delta spreads in a fan shape.

12
Earthquakes

• What is an earthquake?Earthquakes are the
  shaking, rolling or sudden shock of the earths
  surface. They are the Earth's natural means of
  releasing stress. More than a million earthquakes
  rattle the world each year.

13

• Earthquakes most commonly occur along faults in
  the crust.   

Sometimes new landforms are created. Earthquakes
can happen on land and in water. An earthquake
can destroy everything that gets into its path.
It destroys buildings, bridges, dams, and other
structures.
14
Where do earthquakes happen?
15
Why?
Most naturally occurring earthquakes are related
to the tectonic nature of the Earth. Such
earthquakes are called tectonic earthquakes. The
Earth's lithosphere is a patchwork of plates in
slow but constant motion caused by the release to
space of the heat in the Earth's mantle and core.
16
Why continued

• The heat causes the rock in the Earth to warm so
  that the plates move slowly but surely. Plate
  boundaries lock as the plates move past each
  other, creating frictional stress. When the
  frictional stress exceeds a critical value,
  called local strength, an earthquake happens.

17

• The West Coast is most at risk of having an
  earthquake, but earthquakes can happen in the
  Midwest and along the East Coast. Earthquakes can
  be felt over large areas although they usually
  last less than one minute. Earthquakes cannot be
  predicted - although scientists are working on
  it!

18
Quit pushing!!
19
Largest Fault in the US The San Andreas Fault
20

• Natural Disasters - Earthquakes - Fault Lines 

21
Technology and Earthquakes

• Earthquakes generate seismic waves which can be
  detected with a sensitive instrument called a
  seismograph. Advances in seismograph technology
  have increased our understanding of both
  earthquakes and the Earth itself.
• Perhaps the earliest seismograph was invented in
  China A.D. 136 by a m an named Choko.

22
Volcanoes

• A volcano is a mountain or hill formed by the
  accumulation of magma or molten rock. Magma is
  typically produced at depths of 50 to 60 miles
  below the surface because liquid magma is less
  dense than solid rock, it is pushed out of cracks
  in the Earth's surface. Volcanic eruptions can be
  deadly, damaging property and infrastructure.

23
Volcano Types

• Volcanoes are one of the most powerful forces in
  nature. A volcano is a hole in the earths crust.
  The hollow holes that are in volcanoes are called
  craters. There are different types of volcanoes 
  shield-volcanoes, cinder cone volcanoes, lava
  domes and the most common - composite volcanoes.

24
Volcanoes are basically hollowed-out mountains
with connections to the Earths magma core. There
are over 500 volcanoes in the world. The
volcanoes are contained in a circle called the
Ring of Fire.
25

• Volcanic eruptions start in a magma chamber. The
  high pressure of the steams and gasses make the
  magma fill the magma chamber.
• When the chamber is full, the type of eruption
  depends on the amount of gases and silica in the
  magma.
• The amount of silica determines how sticky the
  magma is and the amount of water determines the
  explosive potential of the steam.

26
Evidence of Steam Magma
27

• Volcanoes can form on land but they can also form
  in water. Volcanoes can help build up the Earth's
  surface (constructive) like the developing
  Hawaiian Islands, but volcanoes can also be very
  destructive to the Earth's surface.

28
Destructive Volcanoes

• Volcanoes can endanger anything that happens to
  be in the vicinity of an erupting volcano such as
  humans, property, and agriculture. 
• Volcanoes are destructive because when they erupt
  not only  can they spew hot ash and lava but they
  can also cause other destructive activities to
  occur.

29
Volcanic DiagramNotice the difference in
destruction on either side of the volcano.
30
Volcanic Landslide step 1
Mud flows also may occur with a volcano eruption
engulfing everything in its path..

• Volcanic Landslide step 2

31

• Volcanoes are destructive because when they erupt
  not only  can they spew hot ash and lava but they
  can also cause other destructive activities to
  occur.
• Lava flows can destroy homes, grass, trees, and
  anything else in its destructive path.   The lava
  which is hot melted rock flows from one place to
  another burning everything it touches.

32
Tsunamis and Earthquakes

• Two main destructive forces can be triggered by a
  volcano tsunamis and earthquakes.
• Damage to the Earth's surface caused by a volcano
  is often not repairable but over many, many years
  some new growth may begin to appear.

33
Good Thing/Bad thing

• There are many constructive properties of
  volcanoes. For example, volcanoes help the
  rock-cycle by bringing rocks to the surface to
  form new landforms like islands.  All of the
  Hawaiian Islands were created by volcanoes. There
  is even a new island forming right now.

34

• Another example of a volcanoes' constructive
  force is that if there are enough eruptions or a
  constant lava flow a mountain can form. Some of
  these mountains form on land but many build from
  the bottom of oceans.

35
Here are other ways a volcano can be
constructive...

• volcanic ash can be used as an abrasive or
  cleaning agent
• volcanic ash can act as a mulch
• volcanoes can create geothermal energy
• ashes can make more fertile soil
• To see an animation of an erupting volcano  click
  here.

36
Erosion

• Erosion is a process in which rock and soil are
  broken loose from the earth's surface at one
  location and moved to another.

37
Water Erosion

• Moving water (like a stream) is an important
  agent in the erosion process. Dirt and other
  sediment get in the water and then the moving
  water moves it to a new location.  
• Gravity plays an important role as well in
  erosion gravity pulls down dirt and other stuff
  from the hills and causes erosion.

38
Wind Erosion

• Wind erosion occurs mostly in flat, dry areas and
  close to bodies of water.  Wind erosion removes
  the most fertile part of soil and lowers the soil
  production. That means most crops and plants will
  not make it to harvest time. All that is left
  after wind erosion in soil is the clayish soil
  and silts.

39

• In the 1930s a long dry spell got bad enough it
  turned into dust storms. They called it the Black
  Blizzards and it became known as  the Dust Bowls.
  
• Want to know more? Click here

40
Weathering

• Weathering is the process of decomposition or
  disintegration of rocks and their minerals. That
  is why it is considered a destructive force. The
  rocks and their minerals break down into smaller
  pieces like silt, clay and sand.

41

• The weathering process occurs at or near the
  surface of the earth. In fact, the soil we depend
  on for much of our food is a mixture of bits and
  pieces of weathered rock.

42
Weathering and Water

• One of the major causes of weathering is water.
  Moving waters such as rivers and oceans can
  permanently change the Earth's surface. The
  waters and rivers can carve deep canyons or
  weather cliffs along the seashore causing them to
  fall into the waters.

43

• Rain water can also cause weathering. As it
  rains, rain water can seep into holes and cracks
  in rocks causing weathering and if this water
  freezes inside the rock, this can cause the rock
  to break into smaller pieces.

44
Extreme Heat

• Extreme heat is an example of weathering that can
  cause destructive changes to the surface of the
  earth.
• Rocks that become heated at the surface of the
  earth can expand and then contract. If this
  happens often enough the expansion and
  contraction of rock would eventually cause
  weathering.

45
Plants

• Plant roots grow in cracks of rocks. As they
  grow, they force open the cracks. This is another
  way pieces of rock can be broken off.

46
Weathering and Erosion

• Weathering and erosion often occur at the same
  time. After weathering has broken the rocks into
  smaller pieces, other processes like erosion and
  deposition move the broken pieces to other
  places.
• Weathering is a destructive force because it
  changes rocks by breaking them into smaller
  pieces.

47
Weathering processes are divided into three
categories

•    Physical or Mechanical Weathering
•    Chemical Weathering
•    Biological Weathering

48

• Physical or Mechanical Weathering   breaks
  larger rocks into smaller rocks without changing
  what the rock is made of. Examples
• Chemical Weathering   involves changing what the
  rock is made of. Chemical weathering causes the
  rocks to become weak and eventually crumble.
  Examples
• Biological Weathering is the actual molecular
  breakdown of minerals.
• Example Lichens live on rocks and they slowly
  eat away at the surface of rocks

49
Technology and Flood Control

• http//www.gcwallace.com/ServicesLasVegasFloodCont
  rol.asp

50
(No Transcript)
51
European Flood Control