Plate Tectonics Study Guide

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Plate Tectonics Study Guide
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Key Terms

• Continental Drift Theory that all the
  continents had once been joined together in a
  single landmass and have since drifted apart. The
  continents continue to drift today.
• Pangaea Name of supercontinent of all the
  landmass 200 mya

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• Plate Tectonics The theory of plate tectonics
  explains the formation, movement, and subduction
  of Earths tectonic plates.
• Alfred Wegener Scientist who developed theory
  of Continental Drift.
• Plate Boundary Border between two tectonic
  plates, usually an area of earthquake and volcano
  activity.

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• Convergent Boundary Plate boundary where two
  plates collide.
• Continental crust colliding with continental
  crust Mountain building
• Reverse Fault, Compression, Granite
• Oceanic crust colliding with continental crust
  Ocean crust SUBDUCTS into the mantle and
  explosive volcanoes form on continent.

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• Divergent Boundary The plate border between two
  plates where they move apart. Most divergent
  boundaries are at mid-ocean ridges.
• Divergent boundaries at mid-ocean ridges allow
  magma to rise from the mantle, creating new
  oceanic crust.
• This process is called Seafloor Spreading

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• Transform Boundary Border where two tectonic
  plates slide past each other. Earthquakes occur
  frequently along a transform plate boundary.
• EX. San Andreas Fault in California

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• Lithosphere The rigid outer layer of Earth.
  Mainly compromised of Earths crust.
• Oceanic Crust vs. Continental Crust Oceanic
  crust is composed mainly of basalt. Continental
  crust is mainly granite. Oceanic crust is thicker
  and denser than continental crust.

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• Mantle Solid layer of Earth beneath the crust.
  The rock in this layer is under some much
  pressure and heat that it flows like a fluid.
• Core Outer core is liquid. Inner core is solid.
  Both are composed mainly of iron and nickel.
• Magnetic field Field surrounding Earth created
  by the Earths outer core.

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Question 1 Region A

• Region A is a convergent boundary, continental
  crust is colliding with continental crust.
• Mountain ranges are formed
• This is caused by compression, creating a reverse
  fault.
• Continental crust is made of granite.

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Question 2 Region B

• Region B is also a convergent boundary, in this
  case continental crust and ocean crust are
  converging at a TRENCH
• The denser oceanic crust subducts under the
  continent into the mantle and melts
• This is caused by compression and is a reverse
  fault.
• Continental crust is made of granite, oceanic is
  made of basalt
• Explosive volcanoes form as a result of this
  subduction.

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Question 3 Region C

• Region C is a divergent boundary, oceanic crust
  is diverging at a mid-ocean ridge.
• New oceanic crust is formed as magma quietly
  erupts from the ridge.
• The new ocean crust pushes the older ocean crust
  away from the ridge in both directions (Seafloor
  Spreading)
• If there are no trenches on either side of the
  ridge then the ocean grows in size.

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Question 4 Region D

• Region D is a convergent boundary. Oceanic crust
  is subducting under an island arc at a trench.
• Explosive volcanoes form as a result of the
  subduction.
• Examples Japan, Indonesia, Aleutian Islands,
  Alaska

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Question 5

• Continental Crust Granite
• Oceanic Crust Basalt
• Oceanic Crust subducts under continental crust at
  trenches because basalt is denser than granite

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Question 6 Hot Spots

• Hawaii is located on a hot spot in the mantle
  under the Pacific Plate.
• The magma plume here is hotter than other areas
  so it is less dense and rises.
• As the Pacific Plate moves over the hot spot new
  islands in the chain are created.
• These are shield volcanoes and quiet eruptions.

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Q1 Continental Drift

• Wegeners hypothesis was that all of the
  continents had once been joined together in a
  single landmass 200 mya and have since drifted
  apart.
• Wegener called this supercontinent Pangaea.
• Continental Drift is the theory that the Earths
  tectonic plates are in constant motion,
  colliding, moving away, or sliding against each
  other.

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Evidence for Continental Drift

• Coastlines
• Mountain ranges
• Coal fields
• Glacier evidence
• fossils

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Q3 Alfred Wegener

• Alfred Wegener came up with the idea of
  continental drift.
• His theory was not accepted at first because he
  could not explain how the continents moved

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Q4 Fossil Safari

• Glossopteris fossilized fern found in
  Antarctica, Africa, South America.
• Thecodont small lizard-like dinosaur found in
  N. America and Europe

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Egg Model for Earth

• Egg shell is the lithosphere (crust)
• Cracks in shell formed the plates.
• The egg white represented the mantle which is
  solid rock but has some properties of a fluid
• The egg white is also the thickest layer and is
  beneath the cracked shell.

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Egg Model for Earth

• The Yolk represents the core. The inner core is
  solid and made of iron and nickel, the outer core
  is liquid (not evident in egg model)
• Weaknesses
• Core is off centered
• No liquid outer core
• Plates do not move
• Temperature does not increase

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P.T. Map Q1

• The Atlantic Ocean consists of the North American
  Plate, South American Plate, Eurasian Plate, and
  African Plate
• The Atlantic ocean is growing because of the
  Mid-Atlantic Ridge.
• There are no trenches along the continents to
  subduct old ocean crust

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PT Map Q2

• The Eurasian Plate, Philippine Plate, Pacific
  Plate, and North American Plate converge along
  Japan.
• The Pacific Plate is converging and subducting
  into a trench, forming explosive volcanoes.

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PT Map Q3

• Japan is on a deep-ocean trench.
• The Pacific Plate is subducting into this trench
• This causes frequent volcanoes and earthquakes in
  this area.

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P.T. Map Q4

• The Himalayas are an example of a convergent
  boundary with continental crust colliding with
  continental crust.
• The Indo-Australian Plate is converging with the
  Eurasian Plate.
• The Alps are another example.
• The African plate is converging into the Eurasian
  Plate

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Finding Density of Basalt and Granite

• Materials
• Graduated cylinder
• Water
• scale

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Finding Density of Basalt and Granite

• Mass each rock in grams
• Fill a graduated cylinder to 100 ml
• Role the rock into the cylinder and measure the
  new volume
• Subtract the old volume (100ml) from the new
  volume to find the volume of the rock
• Use the formula DM/V to find the density of each
  rock
• This proves why the ocean crust subducts under
  continental crust