Chapter 4: Section 1: Inside the Earth

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Chapter 4 Section 1 Inside the Earth
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• The Earth is made of different layers which are
  described by their Composition and Physical
  properties

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Composition

• The Earth is divided into
• 3 main layers
• Crust
• Mantle
• Core

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The Crust

• The crust is the outermost layer of the Earth
  with a thickness of 5 to 100 km

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2 Types of Crust

1. Continental crust - land bodies, usually 30 km
   thick! (Mostly granite)
2. Oceanic crust - bottom of water bodies, 5-8 km
   thick. (Mostly basalt)

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Two types of crust
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The Mantle

• thickness of 2,900 km.
• It is so deep that no one has ever seen what it
  looks like.
• Contains most of the Earths mass

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The Core
Is the center of the Earth and is made of Iron
with smaller amounts of Sulfur, Aluminum and
Magnesium, and silicon and oxygen
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• Physical Properties
• of Earths Layers

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• Based upon structure, there are 5 physical
  layers
• ) Lithosphere
• ) Asthenosphere
• ) Mesosphere
• ) Outer core
• ) Inner core

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1.) The Lithosphere

• Outermost layer
• made up of the crust and the rigid upper part of
  the mantle.
• Divided into pieces called tectonic plates.

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2.) The Asthenosphere

• This is the soft layer of the mantle on which
  pieces of the lithosphere move.

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3.) Mesosphere

• Lower part of the mantle

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4.) The Outer Core

• Outer liquid layer of the core

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5. Inner Core

• Solid inner layer of the core

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Tectonic Plates

• Pieces of the lithosphere that move around on the
  asthenosphere.
• Made of continental crust, oceanic crust or both

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Depths of the Earth

• Scientists cannot visit the depths of the Earth
  like the mantle and the core but use seismic
  waves recorded during earthquake activity.

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Seismic Waves

• The device that measures seismic waves is a
  seismograph.

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Section 1 Recap Questions

• What are the 3 main layers of the Earth?
• Crust, Mantle, Core
• What are the 2 components of the crust?
  Continental and Oceanic
• What is the largest layer of Earth?
• The Mantle
• According to their characteristics, what are the
  5 layers Earth can be broken into?
• Lithosphere, Asthenosphere, Mesosphere, Outer
  core, Inner core

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Alfred Wegener 1911
Developed a Theory called the Theory of Plate
Tectonics which states that the Earths
lithosphere is divided into tectonic plates that
move around on top of the asthenosphere. The
continents once formed a single landmass, broke
up, and drifted to their present locations
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Wegeners Theory explains some observations

1.  The continents seem to fit together

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• 2. Fossils of the same plant and animal species
  are found on continents that are on different
  sides of the Atlantic Ocean.

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• 3. Similar types of rock were found on several
  continents.

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• 4. Evidence of the same ancient climatic
  conditions were found on several continents.

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• Wegener proposed that all of the separate
  continents that we see today were once connected
  in a giant landmass called Pangaea which broke up
  about 180 M years ago and formed 2 big pieces
  called Laurasia and Gondwanaland. Then, about 65
  MYA, these broke up and formed the continents
  that we know today.

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Sea Floor Spreading

• As the tectonic plates move away from each other,
  the sea floor spreads apart and magma fills in
  the gap.

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Sea floor spreading is proven by the ages of the
rocks

• As this new crust forms, the older crust gets
  pushed away from the mid-ocean ridge.
• The older crust is farther away from the
  mid-ocean ridge than the younger crust is.

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Magnetic Reversal

• Throughout Earths history, the north and south
  magnetic poles have changed places many times.

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How does Magnetic Reversal Prove Sea Floor
Spreading?
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Plate Tectonics
Theory of Plate Tectonics states that the Earths
lithosphere is divided into tectonic plates that
move around on top of the asthenosphere. The
continents once formed a single landmass, broke
up, and drifted to their present locations
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Boundary

• Boundary - is a place where tectonic plates
  touch.
• 3 types of boundaries (depending on how the
  plates are moving relative to one another)
• 1.) Convergent
• 2.) Divergent
• 3.) Transform

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Convergent Boundary

• Type of Crust ? O-O, C-C, or O-C
• Type of Movement - 2 plates move together often,
  1 oceanic plate moves under another oceanic or
  continental plate in a process called subduction
• Arrows - ??

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Divergent Boundaries

• Type of Crust ? O-O or C-C
• Type of Movement - 2 plates move apart
• Arrows -??

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Stress

• Stress is the amount of force that is applied on
  a given material.

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• Deformation - when rock changes shape due to
  stress

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Pd 2 starts here
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• There are two main types of stress that can act
  on a rock.
• Compression
• Tension

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Compression

• Motion that Occurs
• Rock is squeezed will fold
• What type of boundary?
• Convergent

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Tension

• Motion that Occurs
• Rock is stretched and can break
• What type of boundary?
• Divergent

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Folding

• Folding occurs when rock layers bend due to
  stress in the Earths crust.

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• 3 Types of folding
• Anticline
• Syncline
• Monocline

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Anticline

• Description rock folds downward (like a hill)
• Picture

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Syncline
Description rock folds upwards (like a
u) Picture
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Monocline
Description layers of rock are stacked but
remain horizontal. Picture
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Pd 1, 9 starts here
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Fault

• A crack in the Earths crust along which rocks
  move.

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Fault Blocks

• The blocks of crust on either side of the fault

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• If a fault is cut diagonally, it usually has two
  specific sides.
• a)Hanging wall the upper side of the cut, the
  upper portion sticks out.
• b)Footwall the lower side of the cut, the bottom
  portion sticks out

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Hanging wall Footwall
Hanging Wall
Footwall
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3 Types of Faults

1. Normal
2. Reverse
3. Strike-slip

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Pd 7,8 starts here
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Normal Faults

• Description Stress at a divergent boundary pulls
  Hanging wall down relative to the footwall
• Picture

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Reverse Fault

• Description Compression pushes Hanging wall
  moves up relative to the footwall at a convergent
  boundary
• Picture

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Strike-Slip Fault

• Description Rock breaks moves horizontally
  (transform boundary)
• Picture

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• Mountains

• Mountains are formed when tectonic plates undergo
  compression or tension.

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3 Types of Mountains

1. Folded
2. Fault-block
3. volcanic

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Folded mountains

• Description Rock layers are squeezed together
  pushed upwards

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Fault-Block Mountains

• Description when there is enough tension, a
  large number of normal faults can result.
  Mountains are tilted upwards by faulting will
  have sharp, jagged peaks.

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Volcanic Mountains

• Description-When molten rock erupts into the
  Earths surface, magma pushes the surface of the
  Earth upwards