Download U4-T2.1-Evolution of the Plate Tectonic Theory

Earth Systems 3209
Unit: 4
The Forces Within Earth
Reference:
Chapters 4, 15, 16, 19; Appendix A & B
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Unit 4:
Topic 2.1
Evolution of the Plate Tectonic Theory
Focus on . . .
 describing the evolution of the plate tectonic theory
through the contributions of various scientists.
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Early Ideas of Crustal Movement
 In the early – mid 1900’s, geologists thought that
the ocean basins and continents were fixed. During
the past 70 years these ideas have brought about a
scientific revolution in which new evidence and data
support a slowly but continually moving planet.
 It was not until 1968 that a theory called “Plate
Tectonics” provided reliable evidence supporting a
mobile Earth.
Text Reference:
Chapter 19
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Early Ideas of Plate Tectonics
 Important people of the past and the contribution they
made to support a moving Earth (Plate Tectonics).
1) F. B. Taylor
 In 1910, he published an article explaining
the formation of the Himalayan mountains
by moving continents. His ideas were not
accepted because he failed to provide
supporting evidence.
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Early Ideas of Plate Tectonics
 Important people of the past and the contribution they
made to support a moving Earth (Plate Tectonics).
2) Alfred Wegener
 In 1915, Wegener rattled the scientific community
again when he published articles concerning
continental drift.
 He suggested a super continent called Pangaea
existed approximately 200 million years ago and
since gradually split apart. (evidence was given,
but no mechanism provided to support his ideas).
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Early Ideas of Plate Tectonics
 Important people of the past and the contribution they
made to support a moving Earth (Plate Tectonics).
3) Arthur Holmes
 In 1950’s, he discovered the mechanism to
explain why Earth’s lithosphere can move,
this was referred to as “convection currents”
in the upper mantle (asthenosphere).
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Early Ideas of Plate Tectonics
 Important people of the past and the contribution they
made to support a moving Earth (Plate Tectonics).
4) Alexander DuToit
 In 1937, he mapped the fit of the continents
more accurately by using the continental
margins (shelves) instead of the coastlines.
This is best seen by viewing Africa and South
America.
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Early Ideas of Plate Tectonics
 Important people of the past and the contribution they
made to support a moving Earth (Plate Tectonics).
5) Harry Hess and Robert Deitz
 In the 1960’s, these two scientist proposed
the “Sea Floor Spreading” hypothesis and
suggested that the sea-floor can be no older
than 200 million years.
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Early Ideas of Plate Tectonics
 Important people of the past and the contribution they
made to support a moving Earth (Plate Tectonics).
6) Frederick Vine and Drummond Mathews
 In 1963, these two scientist studied the
ocean floor and found that the magnetism in
the rocks appear to change (reverse) as you
move away from oceanic ridges.
 This idea was called “magnetic reversals”
and is known to support the idea of Sea
Floor Spreading (plate tectonics theory).
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Early Ideas of Plate Tectonics
 Important people of the past and the contribution they
made to support a moving Earth (Plate Tectonics).
7) J. Tuzo Wilson
 Was a Canadian geologist who proposed the existence
of “plates” on Earth’s surface as a result of mapping the
world’s volcanoes and earthquakes. He put forth the
idea that, “Earth consisted of several fragments called
plates, instead of being made up of one rigid, solid layer”.
This revolutionized the way scientist think of Earth today.
 He also proposed the existence of transform faults along
plate boundaries; and that stationary hotspots in Earth’s
mantle caused volcanism within plates.
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Early Ideas of Plate Tectonics
 Important people of the past and the contribution they
made to support a moving Earth (Plate Tectonics).
8) Xavier Le Pichon and Dan McKenzie
 McKenzie published the first paper on the principles of
plate tectonics
 Le Pichon was the first to demonstrate on computer
the motion of six tectonic plates. He demonstrated that
the total crust created at the ocean ridges equaled the
amount of crust lost due to subduction at oceanic
trenches.
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Example 1:
Which Canadian scientist was responsible for
the theory of plate tectonics?
(A) Alfred Wegener
(C) Harry Hess
(B) Robert Deitz
(D) Tuzo Wilson
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Example 2:
Which scientists contributed to Plate Tectonics Theory
through their work on magnetic reversals?
(A) Hess and DuToit
(C) Vine and Matthews
(B) McKenzie and Lepichon
(D) Wegener and Wilson
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Your Turn . . .
Take the time and complete the following questions . . .
(Solutions to follow)
Question:
Which scientists contributed to Plate Tectonics
Theory through their work on seafloor spreading?
(A) Hess and Deitz
(C) Vine and Matthews
(B) McKenzie and Lepichon
(D) Wegener and Wilson
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Solutions . . .
Questions:
Which scientists contributed to Plate Tectonics
Theory through their work on seafloor spreading?
(A) Hess and Deitz
(C) Vine and Matthews
(B) McKenzie and Lepichon
(D) Wegener and Wilson
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Summary . . .
Overview of Points covered:
Scientist that made significant contributions to the plate tectonic
theory in the past include;
1)
2)
3)
4)
5)
6)
7)
8)
Frank Taylor
Alfred Wegener
Alexander DuToit
Arthur Holmes
Harry Hess and Robert Deitz
Fredrick Vine and Drummond Matthews
J. Tuzo Wilson
Xavier Le Pichon and Dan McKenzie
Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador