1. Plate Tectonics

3. Moving Continents? The idea that the Earth's crust is not completely stable is not new. The idea that the Earth's crust is not completely stable is not new. Understanding the WHY and HOW of this has been a problem since the beginning of geological studies. Understanding the WHY and HOW of this has been a problem since the beginning of geological studies.

4. 1 st Step Have to have evidence. Have to have evidence. Way back in 1620 Francis Bacon noted the similarity of the coastlines of Africa and South America. Way back in 1620 Francis Bacon noted the similarity of the coastlines of Africa and South America. In the 1800’s Antonio Snider-Pelligrini noticed similar fossil plants in coal beds of Europe and North America In the 1800’s Antonio Snider-Pelligrini noticed similar fossil plants in coal beds of Europe and North America In 1908 Taylor and Baker noticed a correlation of global mountain chains. In 1908 Taylor and Baker noticed a correlation of global mountain chains.

5. What is the problem? The discoveries these scientists made were going against the belief that the continents were stable and fixed. The discoveries these scientists made were going against the belief that the continents were stable and fixed. To even think that the continents could be moving was ridiculous to people in the past and if a scientist were to propose it they would be ridiculed. To even think that the continents could be moving was ridiculous to people in the past and if a scientist were to propose it they would be ridiculed.

6. The Start of Something New Alfred Wegener shocked the world when he went against common belief and proposed his theory of Continental Drift Alfred Wegener shocked the world when he went against common belief and proposed his theory of Continental Drift He claimed that the continents can move and that all the continents had once been joined to form one large super-continent called Pangaea (all land), and the ocean was called Panthalassia (all ocean) He claimed that the continents can move and that all the continents had once been joined to form one large super-continent called Pangaea (all land), and the ocean was called Panthalassia (all ocean)

7. Continental Drift Wegener was in his school library one night when he found some scientific articles describing the discovery of similar fossil plants in coal beds of Europe and North America. Wegener was in his school library one night when he found some scientific articles describing the discovery of similar fossil plants in coal beds of Europe and North America. Intrigued by the article Wegener began to look for more occurrences like this. Intrigued by the article Wegener began to look for more occurrences like this.

8. Wegener’s Evidence His curiosity lead him to discover multiple lines of evidence that he could use to develop his theory. His curiosity lead him to discover multiple lines of evidence that he could use to develop his theory. What was his evidence? What was his evidence?

9. Puzzle-like Fit

10. Matching Fossils

11. Matching Mountain Chains

12. Matching Glacial Evidence

13. This Guy!

14. Continental Drift In 1915 Wegener published his theory of Continental Drift with his supporting evidence, but it didn’t go over so well. In 1915 Wegener published his theory of Continental Drift with his supporting evidence, but it didn’t go over so well. "Can we call geology a science when there exists such differences of opinion on fundamental matters as to make it possible for such a theory as this to run wild.“ "Can we call geology a science when there exists such differences of opinion on fundamental matters as to make it possible for such a theory as this to run wild.“ Wegener's theory is a fairly tale and should be ignored due to its deleterious effect on students Wegener's theory is a fairly tale and should be ignored due to its deleterious effect on students

15. What’s wrong with it? Wegener developed a theory with plenty of supporting evidence, so what is the problem with it? Wegener developed a theory with plenty of supporting evidence, so what is the problem with it? Why wasn’t his theory excepted? Why wasn’t his theory excepted?

16. Objections HE HAD NO MECHANISM!!!!!! HE HAD NO MECHANISM!!!!!! Wegener developed his entire theory, but forgot to think about how the continents move. Wegener developed his entire theory, but forgot to think about how the continents move. He said that the continents “plowed” through the ocean crust He said that the continents “plowed” through the ocean crust

17. Objections Wegener worked so hard to develop this theory and because of his mechanism he was laughed at and ridiculed Wegener worked so hard to develop this theory and because of his mechanism he was laughed at and ridiculed He was not respected in the science community and his ideas were thought to be fairy tale He was not respected in the science community and his ideas were thought to be fairy tale But Wegener did not give up But Wegener did not give up

18. A Life of Finding the Truth Despite all of the criticism Wegener was receiving he still went ahead and continued his search for a mechanism Despite all of the criticism Wegener was receiving he still went ahead and continued his search for a mechanism He knew that his theory was valid, but could not find the mechanism He knew that his theory was valid, but could not find the mechanism He devoted the rest of his life towards research and discovery of the true reason how continents move He devoted the rest of his life towards research and discovery of the true reason how continents move

19. Alfred’s Last Stand In 1930 Wegener went on an expedition to Greenland but never came back. In 1930 Wegener went on an expedition to Greenland but never came back. All of his work went for nothing and he received no recognition for the contributions that he made towards science All of his work went for nothing and he received no recognition for the contributions that he made towards science

20. Yes, it is a real squirrel and yes it is truly waterskiing!

21. Heading in the Right Direction Despite all of Wegner’s hard work he did not gain any respect until well after his death Despite all of Wegner’s hard work he did not gain any respect until well after his death In the 1950’s and 1960’s discoveries about earthquakes, magnetism, and the age of rocks on the ocean floor added support to some of Wegener’s ideas. In the 1950’s and 1960’s discoveries about earthquakes, magnetism, and the age of rocks on the ocean floor added support to some of Wegener’s ideas.

22. Harry Hess WWII Naval Submarine Officer (1939-1945) WWII Naval Submarine Officer (1939-1945) Developed this idea of Sea Floor Spreading. Developed this idea of Sea Floor Spreading. He says that new ocean crust is created at Mid Ocean Ridges and old crust is destroyed in deep trenches. He says that new ocean crust is created at Mid Ocean Ridges and old crust is destroyed in deep trenches.

24. How did he come up with this? While mapping the ocean floor Harry Hess discovered a gigantic volcanic ridge system that nearly stretched around the world. While mapping the ocean floor Harry Hess discovered a gigantic volcanic ridge system that nearly stretched around the world. a ridge system 65,000 km long a ridge system 65,000 km long the most extensive mountain range in the world the most extensive mountain range in the world The Mid-Atlantic Ridge The Mid-Atlantic Ridge is the best known is the best known divides Atlantic Ocean basin in two nearly equal parts divides Atlantic Ocean basin in two nearly equal parts

25. Atlantic Ocean Basin

26. One More Key Component In the 1960’s Drummond Matthews and Frederick Vine (known as Matthews and Vine) took a closer look at the ocean floor and provided even more evidence to support the idea of sea floor spreading. In the 1960’s Drummond Matthews and Frederick Vine (known as Matthews and Vine) took a closer look at the ocean floor and provided even more evidence to support the idea of sea floor spreading.

27. Magnetic Reversals Earth has a magnetic field Earth has a magnetic field Similar to a giant dipole magnet Similar to a giant dipole magnet There is a magnetic north and a magnetic south There is a magnetic north and a magnetic south Magnetic poles usually match up with geographic north and south. Magnetic poles usually match up with geographic north and south.

28. Rocks and Magnetism Ocean crust is composed of a rock known as basalt. Ocean crust is composed of a rock known as basalt. Basalt is very rich in magnesium and iron. Basalt is very rich in magnesium and iron. Formed when lava cools at the surface Formed when lava cools at the surface When the lava cools, the magnetic particles line up with the magnetic poles of the Earth. When the lava cools, the magnetic particles line up with the magnetic poles of the Earth. But Earth’s magnetic field isn’t always pointing in the same direction. But Earth’s magnetic field isn’t always pointing in the same direction.

29. Magnetic Reversals Earth’s present magnetic field is called normal Earth’s present magnetic field is called normal Magnetic north matches with geographic north Magnetic north matches with geographic north magnetic south matches with geographic south magnetic south matches with geographic south At various times in the past, Earth’s magnetic field has completely reversed At various times in the past, Earth’s magnetic field has completely reversed magnetic north matches with geographic south magnetic north matches with geographic south magnetic south matches with geographic north magnetic south matches with geographic north

31. Matthews and Vine also noticed that the age of the seafloor increased as you move from the mid-ocean ridge towards the continents. Matthews and Vine also noticed that the age of the seafloor increased as you move from the mid-ocean ridge towards the continents. Matthews and Vine

32. How do Matthews and Vine’s discoveries relate to Seafloor Spreading?

33. Tying it Together Seafloor spreading theory indicates that Seafloor spreading theory indicates that Oceanic crust is created at mid-ocean ridges (young) Oceanic crust is created at mid-ocean ridges (young) Destroyed at trenches near continents (old) Destroyed at trenches near continents (old) This means that ocean crust is created in the middle of the ocean, being pushed to the side until it is destroyed in a trench. This means that ocean crust is created in the middle of the ocean, being pushed to the side until it is destroyed in a trench. Magnetic reversals show that the ocean is spreading from the middle with its symmetrical patterns of magnetic reversals. Magnetic reversals show that the ocean is spreading from the middle with its symmetrical patterns of magnetic reversals. The seafloor gets older as you move from the mid- ocean ridge outward which shows that new crust forms in the middle and is destroyed on the outside. The seafloor gets older as you move from the mid- ocean ridge outward which shows that new crust forms in the middle and is destroyed on the outside.

34. SHHHHHHHHHHH!

35. Plate Tectonics The outer portion of the Earth, the lithosphere, is composed of large irregular sections or plates that “float” on the asthenosphere. The outer portion of the Earth, the lithosphere, is composed of large irregular sections or plates that “float” on the asthenosphere.

36. Terminology Lithosphere – “rock layer” – made up of the crust and the uppermost part of the mantle. Lithosphere – “rock layer” – made up of the crust and the uppermost part of the mantle. This puts the “plate” in plate tectonics! This puts the “plate” in plate tectonics! Asthenosphere – “weak layer” – made up of the upper part of the mantle that the lithosphere moves over top. Asthenosphere – “weak layer” – made up of the upper part of the mantle that the lithosphere moves over top.

38. Plate Tectonics The continents are embedded in lithospheric plates. As these plates move, they carry the continents with them. The ocean basins are part of lithospheric plates as well. The continents are embedded in lithospheric plates. As these plates move, they carry the continents with them. The ocean basins are part of lithospheric plates as well.

40. Plate Tectonics So, let me get this straight….. So, let me get this straight….. The outer portion of the Earth, the lithosphere (crust and uppermost mantle), is broken up into large irregular plates The outer portion of the Earth, the lithosphere (crust and uppermost mantle), is broken up into large irregular plates These plates contain oceanic and continental crust These plates contain oceanic and continental crust The plates “float” on the asthenosphere (upper part of mantle directly under the lithosphere) carrying the continents on them The plates “float” on the asthenosphere (upper part of mantle directly under the lithosphere) carrying the continents on them

42. Hold Up Why do we care about plate tectonics? Why do we care about plate tectonics? Because it explains the distribution and formation of volcanoes, earthquakes, and mountains. Because it explains the distribution and formation of volcanoes, earthquakes, and mountains.

43. Assignment In front of you is a map of the world and a chart with earthquakes, volcanoes, and their longitude and latitude. You need to plot each of these on your map putting an “E” for earthquake in one color, and a “V” for volcano in a different color. Once you finish that you will need to answer some guiding questions on the back. In front of you is a map of the world and a chart with earthquakes, volcanoes, and their longitude and latitude. You need to plot each of these on your map putting an “E” for earthquake in one color, and a “V” for volcano in a different color. Once you finish that you will need to answer some guiding questions on the back.

44. Questions Do you notice any trends associated with the location of the earthquakes and volcanoes? Do you notice any trends associated with the location of the earthquakes and volcanoes? Why do you think the volcanoes and earthquakes are occurring where they do? Why do you think the volcanoes and earthquakes are occurring where they do? In a different color find three possible locations for both volcanoes and earthquakes, then circle them. In a different color find three possible locations for both volcanoes and earthquakes, then circle them.

45. Look Familiar

46. Plate Tectonics As the plates move and interact at their boundary they create things like earthquakes, volcanoes, and mountains. As the plates move and interact at their boundary they create things like earthquakes, volcanoes, and mountains.

47. Moving Plates Remember that the Lithospheric plates are floating on top of the asthenosphere. Remember that the Lithospheric plates are floating on top of the asthenosphere. The asthenosphere is the upper portion of the mantle. The asthenosphere is the upper portion of the mantle. What two layers is the mantle between? What two layers is the mantle between? What do we know about these layers? What do we know about these layers?

48. Mantle Convection The mantle is undergoing Convection. The mantle is undergoing Convection. Convection is the transfer of heat through movement of a material. Convection is the transfer of heat through movement of a material.

50. Plate Boundaries

51. Three Types Convergent  Convergent  Divergent   Divergent   Transform  Transform  

52. Convergent

53. Divergent

54. Transform

55. How fast are they moving?