INVESTIGATING PLATE MOVEMENT AND FAULTS

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LESSON 15

• INVESTIGATING PLATE MOVEMENT AND FAULTS

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INTRODUCTION

• What does the word model mean to you?
• Miniature version
• Used for study
• Somethings too large to view

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OBJECTIVES

• Describe what a model is and distinguish models
  from real objects or events. Use models to
  simulate the movement of lithospheric plates as
  they collide, separate, and slide past one
  another.
• Use a globe and a map to find evidence of plate
  movement and to identify landforms that result
  from plate movement.

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• Classify materials as either brittle or ductile.
• Investigate the effects of applying a force to a
  model of a fault.

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GETTING STARTED

• Look at the wall map called This Dynamic
  Planet.
• How is this map different from others you have
  seen?
• How is it the same?

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• Look at student Sheet 14.1.
• What patterns do you notice in the location of
  volcanoes and earthquakes?
• Look at the plates shown on the map. Is there
  any relationship between the locations of
  earthquakes and volcanoes on the earth and the
  boundaries, or outer edges, of plates?
• What ideas do you have to explain this
  relationship?

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Lets view the CD-ROM, The Theory of Plate
Tectonics

• Record the following in your notebooks
• A. How do plates move?
• B. How does plate movement cause earthquakes,
  volcanoes, mountains, and trenches?

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MODELS

• A. How are the map and computer images used in
  this lesson like the real earth? How are they
  different?
• The map and computer images are models of the
  earth.
• B. What are some examples of models?
• Globe, map, tornado in a bottle
• C. Write a working definition for the word
  model.
• A representation of an object or event that is
  too large, too small or complicated to be viewed
  or studied.
• Lets look at the models well use for this
  lesson.

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Inquiry 15.1Using a Simple Model of Plate
Movement

• Look at the blue and green foam pads used in this
  activity and record their properties.
• Density, appearance, thickness, weight, and
  size.

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Predict

• How would each pad respond if we did the
  following
• Pulled on the pad from opposite ends
• Pushed on the pad at opposite ends
• Slid two pads past one another
• Collided two pads by pushing them together

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Test and Record

• As each foam pad is demonstrated, record in your
  notebook what happens. Use a table to record your
  observations.
• pull push slide collide

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REFLECTIONS 15.1

• A. How did the pads behave when pulled from
  opposite ends?
• The pads were stretched thin. The blue pad was
  more stretchy.
• B. How did the pads behave when compressed?
• The pads foldedresembling mountains

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• C. If oceanic plates are colder, denser, and
  thinner than continental plates are, which pad do
  you think represented oceanic plates? Which pad
  represented continental plates?
• The thin, blue, dense pads represented oceanic
  plates. The thick green pads represented
  continental plates.
• D. How did the density of the pads affect the
  way they behaved when you made them collide?
• The dense blue pads always moved beneath the less
  dense green pads.

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• E. When do colliding plates on the earth form
  mountains?
• Mountains form when two continental plates of a
  similar density collide.
• F. When do colliding plates form trenches?
• Trenches form when a dense oceanic plate collides
  with a less dense continental plate.
• G. Why would a more dense oceanic plate slide
  under a less dense continental plate?
• Something more dense usually moves beneath
  something less dense.

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• H. Can plates ever move without forming new
  land? If so, when?
• No new land forms when plates slide past one
  another.
• I. How do you think colliding plates on the
  earth cause earthquakes?
• Colliding plates either bend or fracture the
  land earthquakes can form when rock fractures.

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Read pgs. 174, 175

• Colliding, Sliding, and Separating Plates

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INQUIRY 15.2Using the Moving Plates Model

• Turn to page 176 in your Catastrophic Events book
  and follow the procedure listed as its
  demonstrated for you.

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REFLECTIONS 15.2

• A. How do you think the Moving Plates Model shows
  what happens on the earth when two plates
  separate?
• It shows the form they took as they moved.
• B. What causes the ocean floor to separate and
  grow?
• Newly melted rock rises and pushes aside the old
  rock.

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• C. Think about what happened to the black belt as
  it reached the edges of the models lid. What
  landform is created when the ocean floor sinks
  back into the earth?
• A trench forms
• D. What patterns did you observe in the shapes
  of Africa and South America?
• They fit together like puzzle pieces.

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• E. How did the shapes of these continents
  compare with the shape of the Mid-Atlantic Ridge?
• The MAR has the same shape as the coastlines of
  these continents, which border the Atlantic.
  This is because the continents broke apart as the
  ridge formed.
• F. What landform is created when plates separate?
  Give an example.
• A ridge forms. Ex The Mid-Atlantic Ridge.

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• G. What landform is created when two continental
  plates collide? Give an example.
• A mountain forms. Ex The Appalachian Mountains
  (North Amer)

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INQUIRY 15.3Investigating Faults With Models

• Turn to page 179, 181 in your Catastrophic Events
  book and follow the procedure listed on these
  pages.

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REFLECTIONS 15.3

• A. How did the amount of friction along the
  fault affect the amount of force needed to
  rupture the fault? Use data to support your
  answer.
• The greater the friction, the more force is
  needed to rupture the fault. The hooks and loops
  of the Velcro act like protrusions that connect
  the rock across the rock.

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• B. Under what conditions did the blocks rupture
  more abruptly?
• The greater the force applied to the block, the
  more abrupt the rupture.
• C. Under what conditions did the block slip
  (more slowly) but not rupture?
• When two strips of loop Velcro are side by side,
  the friction along the fault was at its lowest.
  When resistance along a fault is low, blocks of
  rock can slip without faulting.

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• D. Think about what happened with the masking
  tape. Is there any sign on the earths surface
  that the earth is moving slowly beneath the
  crust?
• Wrinkles in a sidewalk or on a road are signs
  that pressure is building up along a fault. This
  is called creep.