SWBAT: Review layers of the earth and define

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SWBAT Review layers of the earth and define
Plate Tectonics IOT identify what evidence is
needed to prove the theory of plate tectonics

• Drill What are earths layers?

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• STRUCTURE OF THE EARTH AND
• PLATE TECTONICS

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The Internal Structure of the Earth

• The internal structure of the earth can be broken
  down into 3 major zones

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The Core

• high density of nickel (Ni) and iron (Fe)
• diameter 2200 miles
• temperatures 4000o-10,000o F.

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The Mantle

• predominantly (but not completely) rigid
• solid with plastic qualities
• contains large amounts of the elements silicon
  (Si), iron (Fe), and magnesium (Mg)
• measures 1700-1800 miles thick

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The Crust

• brittle zone
• varies in thickness from 6-40 miles thickest in
  the mountains and thinnest in the ocean basins

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The Crust

• brittle zone
• varies in thickness from 6-40 miles thickest in
  the mountains and thinnest in the ocean basins

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Plate Tectonics A Theory

• Plate Tectonics A theory that attempts to
  explain massive crustal re-arrangment based on
  the movement of continent sized lithospheric
  plates.

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Plate Tectonics A Theory

• Plate Tectonics A theory that attempts to
  explain massive crustal re-arrangment based on
  the movement of continent sized lithospheric
  plates.
• Theory of Continental Drift
• Proposed by Alfred Wegner in 1915

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Plate Tectonics A Theory (and a Proof by the
Prof )

• To prove the theory of plate tectonics I must
• prove that Pangea existed (what was here before
  this)
• provide a mechanism (motor) for change
• provide a structure that would allow for change
• connect all three points above to large scale
  changes on the Earths surface

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Homework Read pgs 247Be prepared to tell me
what the Lithosphere and asthenosphere are.
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SWBAT provide evidence that Pangea existed IOT
help prove the theory of Plate Tectonics

• Drill Label the arrows with either the
  Lithosphere or the Asthenosphere

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Pangaea The Greatest Grandaddy of em all

• About 200 million years ago the continents were
  all connected into 1 super continent called
  PANGEA (which means "all earth").

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Pangea The Greatest Grandaddy of em all

• Until recently this was just a theory without any
  practical or empirical evidence. However,
  evidence for the movement of crustal/lithospheric
  plates can be found in
• 1 the "fit" of the continents
• 2 fossil evidence on opposite
  coastlines
• 3 rock types and structural
  similarities
• 4 paleoclimatic evidence
• 5 paleomagnetic evidence

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Evidence of Pangea (The First Part of the Proof
by the Prof)

• 1. The Fit of The Continents

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Evidence of Pangea (The First Part of the Proof
by the Prof)

• 2. Fossil Evidence on Opposite Coastlines
• Animal Fossils
• Cynognathus
• Mesosaurus
• Lystrosaurus
• Plant Fossils
• Glossopterix

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Cynognathus was a meter-long predator of the
Lower Triassic.Fossils have so far been
recovered from South Africa, South America, China
and Antarctica.
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Evidence of PangeaFossil Evidence
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Early aquatic relative of reptiles, found
as fossils from the Early Permian Period (299
million to 271 million years ago) in South Africa
and South America. Roughly 1 meter long
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Evidence of Pangea Fossil Evidence
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AGEEarly Triassic, 240 million years
agoSIZEAdults about 1 meter longMEANING OF
NAME'Shovel reptile'Lystrosaurus has long
been known from many parts of the ancient
megacontinent Gondwana, although it has yet to be
found in Australia. It is known, for example, in
Antarctica, India, and Africa. In recent decades
it has been found in Russia, China and Mongolia.
This may be the result of movement of animals
from Gondwana across the large landmass of
northern and southern continents combined
Pangaea, at the time Lystrosaurus lived.
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Evidence of Pangea Fossil Evidence
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Evidence of Pangea Fossil Evidence
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Evidence of Pangea Fossil Evidence
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Evidence of Pangea (The First Part of the Proof
by the Prof)

• 3. Rock Types and Structural Similarities

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Evidence of Pangea (The First Part of the Proof
by the Prof)
4. Paleoclimatic Evidence - evidence of ancient
climates
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Evidence of Pangea (The First Part of the Proof
by the Prof)

• 5. Paleomagnetic Evidence

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• The map illustrates the types of plate boundaries
  and the directions of plate movements. Note the
  examples given for the locations of each type of
  plate boundary and the consequences of plate
  movement along these boundaries.

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A Structure to Build On (The Third Part of the
Proof by the Prof)
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A Structure to Build OnThe First Step

• 1909 Andrija Mohorovicic presented the first
  concrete evidence for the layering of the earth
• the velocity of seismic waves increased abruptly
  at approx. 50 km. below the surface of the earth
• coincides with the break between the crust and
  the mantle
• indicates a significant change in the mineral
  composition of the earth
• This boundary layer separates the crust from the
  mantle and is known as the MOHOROVICIC
  DISCONTINUITY. For ease this is often shortened
  to the MOHO.

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A Structure to Build OnThe First Step
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The Lithosphere and the Asthenosphere

• In addition to the "crust" and the "mantle"
  there are 2 very important zones called the
  asthenosphere and the lithosphere.

• The lithosphere includes the upper mantle and the
  crust of the earth glides over the underlying
  asthenosphere.
• 2. The asthenosphere is a partially molten region
  which has plastic characteristics

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The Lithosphere and the Asthenosphere

• In addition to the "crust" and the "mantle"
  there are 2 very important zones called the
  asthenosphere and the lithosphere.
• The major difference
• the lithosphere is brittle and therefore cracks
  and breaks
• the asthenosphere is plastic and deforms without
  breaking.

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The Lithosphere

• The lithosphere is a combination of the oceanic
  and continental crusts moving over the molten
  asthenosphere.
• The lithosphere is composed of 15 major plates
  which are sliding against each other, colliding,
  or drifting apart.

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The Asthenosphere
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The Plates Ocean vs. Continent

• If we focus for a moment on the lithosphere we
  can isolate two types of crustal material
  oceanic crust and continental crust

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The Plates Ocean vs. Continent

• Continental Crust
• composed predominantly of the elements
  Silicon(Si) and Aluminum (Al)
• SG 2.7 (more on this in a moment)

• Ocean Crust
• composed predominantly of the elements Silicon
  (Si) and Magnesium (Mg)
• SG 3.0

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Specific Gravity

• Specific gravity the ratio of the weight of a
  given volume of material to the weight of an
  equal volume of water
• The differences in specific gravity will be
  important when we discuss the process of
  subduction.

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Were Outta Here (or how the Big Kahuna Moved
On) (a.k.a.The Second Part of the Proof by the
Prof)

• As we stated previously the lithosphere is
  composed of 13 plates which are sliding against
  each other, colliding, or drifting apart.
• The question is How are the lithospheric plates
  moving?

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Objective SWBAT identify the three theories of
movement IOT prove the theory of plate tectonics

• Drill What evidence do we have that Pangaea
  Existed

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Three Possible Theories of Movement (The Second
Part of the Proof by the Prof)

1. there are huge convectional currents emanating
   from the core which carry the lithospheric plates
2. convection cells confined to the upper mantle
   which move the lithospheric plates, and
3. hot, thermal plumes which confine the rise of
   heated material to certain areas below the earth
   which drive plates apart.

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Three Possible Theories of Movement

1. there are huge convectional currents emanating
   from the core which move the lithospheric plates

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Three Possible Theories of Movement
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Three Possible Theories of Movement
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Three Possible Theories of Movement

• 2. convection cells confined to the upper mantle
  which move the lithospheric plates

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Three Possible Theories of Movement

• 3. hot, thermal plumes which confine the rise of
  heated material to certain areas below the earth
  which drive plates apart.

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Three Possible Theories of Movement
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Three Possible Theories of Movement
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The Effects of Movement The Boundaries (The
Fourth Part of the Proof by the Prof)

1. DIVERGENT BOUNDARIES (SPREADING CENTERS)
2. TRANSFORM FAULT BOUNDARIES
3. CONVERGENT BOUNDARIES (SUBDUCTION ZONES)

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The Effects of Movement The Boundaries (The
Fourth Part of the Proof by the Prof)

1. DIVERGENT BOUNDARIES
   (SPREADING CENTERS)
2. occur when two (2) lithospheric plates are moving
   away from each other.

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The Effects of Movement The Boundaries (The
Fourth Part of the Proof by the Prof)

1. DIVERGENT BOUNDARIES
   (SPREADING CENTERS)
2. occur when two (2) lithospheric plates are moving
   away from each other.

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The Effects of Movement The Boundaries (The
Fourth Part of the Proof by the Prof)

1. DIVERGENT BOUNDARIES
   (SPREADING CENTERS)
2. occur when two (2) lithospheric plates are moving
   away from each other.
3. Wherever this type of boundary occurs an ocean
   basin will be developed.

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The Effects of Movement The Boundaries (The
Fourth Part of the Proof by the Prof)

• DIVERGENT BOUNDARIES
  (SPREADING CENTERS)
• occur when two (2) lithospheric plates are moving
  away from each other.
• Wherever this type of boundary occurs an ocean
  basin will be developed.
• Examples of divergent boundaries
• the Great Rift Valley of Africa
• the Red Sea
• Atlantic Ocean (at the Mid-Atlantic Ridge)

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Great Rift Valley of Africa
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The Red Sea
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The Effects of Movement The Boundaries (The
Fourth Part of the Proof by the Prof)

• TRANSFORM FAULT BOUNDARIES
• join convergent and divergent boundaries
  -changing one type of boundary into another
• Transform boundaries are usually found in
  association with mid-ocean ridges, and most of
  them are below sea level. One exception is along
  the San Andreas fault past the North American
  Plate

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San Andreas Fault
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Objective SWBAT identify properties of plate
boundaries IOT prove the theory of plate
tectonics.Drill What is the difference between
a transform boundary and a divergent boundary.
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The Effects of Movement The Boundaries (The
Fourth Part of the Proof by the Prof)

• CONVERGENT BOUNDARIES
  (SUBDUCTION ZONES)
• Convergent boundaries occur when two (2)
  lithospheric plates collide, resulting in the
  formation of a SUBDUCTION ZONE
• Subduction occurs when one lithospheric plate is
  forced under another lithospheric plate and into
  the asthenosphere.
• With 2 types of lithospheric plates there are 3
  possible combinations
• a continental plate colliding with an oceanic
  plate (or visa versa)
• two continental plates colliding
• two oceanic plates colliding

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The Effects of Movement The Boundaries (The
Fourth Part of the Proof by the Prof)

• a continental-oceanic plate collision
• Remember that the specific gravity of an oceanic
  plate is higher than that of a continental plate
  (WHY?).
• When this type of collision occurs the denser
  oceanic plate is forced under (SUBDUCTED) the
  continental plate.
• This type of collision generates deep trenches,
  high mountains, and volcanoes
• Examples of this boundary occurr along the west
  coast of the United States (Pacific Northwest)
  and South America.

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• b continental-continental plate collision
• when this type of collision occurs both plates
  have the same specific gravity so it is
  difficult, at first, to tell which plate will be
  subducted.
• This type of collision produces large scale
  mountains there is no evidence of a trench and
  there are no volcanoes (Why?)
• Examples of continent-continent collisions
  include the Australian Plate (India) colliding
  with the Eurasian Plate to form the Himalayas.

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The Indian Subcontinent
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• c ocean plate-ocean plate collision
• Just as in the case where 2 continents collide
  this type of collision involves 2 plates which
  have the same density and specific gravity. Just
  as in the above example, the plate with the least
  mass will be subducted.
• Examples of this type of plate boundary can be
  found where the Philipine plate is colliding with
  the Pacific Plate.

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Bringing it all Together
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THE END
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Objective SWBAT apply concepts of plate
tectonics IOT identify the earths physical
features and processes as part of a working
system.

• Drill Identify the type of plate boundary from
  the satellite images.

B
A
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Try these..(he he he)
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