1. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Earth Systems 3209 Unit: 4 The Forces Within Earth Reference: Chapters 4, 15, 16, 19; Appendix A & B

2. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Evolution of the Plate Tectonic Theory Unit 4: Topic 2.1 Focus on...  describing the evolution of the plate tectonic theory through the contributions of various scientists.

3. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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

4. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador  Important people of the past and the contribution they made to support a moving Earth (Plate Tectonics). Early Ideas of 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.

5. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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).  Important people of the past and the contribution they made to support a moving Earth (Plate Tectonics). Early Ideas of Plate Tectonics

6. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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).  Important people of the past and the contribution they made to support a moving Earth (Plate Tectonics). Early Ideas of Plate Tectonics

7. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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.  Important people of the past and the contribution they made to support a moving Earth (Plate Tectonics). Early Ideas of Plate Tectonics

8. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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.  Important people of the past and the contribution they made to support a moving Earth (Plate Tectonics). Early Ideas of Plate Tectonics

9. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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).  Important people of the past and the contribution they made to support a moving Earth (Plate Tectonics). Early Ideas of Plate Tectonics

10. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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.  Important people of the past and the contribution they made to support a moving Earth (Plate Tectonics). Early Ideas of Plate Tectonics

11. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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.  Important people of the past and the contribution they made to support a moving Earth (Plate Tectonics). Early Ideas of Plate Tectonics

12. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Example 1: Which Canadian scientist was responsible for the theory of plate tectonics? (A) Alfred Wegener(B) Robert Deitz (C) Harry Hess(D) Tuzo Wilson

13. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Example 2: Which scientists contributed to Plate Tectonics Theory through their work on magnetic reversals? (A) Hess and DuToit(B) McKenzie and Lepichon (C) Vine and Matthews(D) Wegener and Wilson

14. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador 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(B) McKenzie and Lepichon (C) Vine and Matthews(D) Wegener and Wilson

15. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Solutions... Questions: Which scientists contributed to Plate Tectonics Theory through their work on seafloor spreading? (A) Hess and Deitz(B) McKenzie and Lepichon (C) Vine and Matthews(D) Wegener and Wilson

16. Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Summary... Overview of Points covered: Scientist that made significant contributions to the plate tectonic theory in the past include; 1)Frank Taylor 2)Alfred Wegener 3)Alexander DuToit 4)Arthur Holmes 5)Harry Hess and Robert Deitz 6)Fredrick Vine and Drummond Matthews 7)J. Tuzo Wilson 8)Xavier Le Pichon and Dan McKenzie