Drill: What are earths layers?

1. SWBAT: Review layers of the earth and define “Plate Tectonics” IOT identify what evidence is needed to prove the theory of plate tectonics Drill: What are earths layers?

2. STRUCTURE OF THE EARTH AND PLATE TECTONICS

3. Mantle Crust Core The Internal Structure of the Earth The internal structure of the earth can be broken down into 3 major zones

4. separated into 2 zones • inner core • solid • 800 miles in thickness • outer core • liquid • measures about 1400 miles in thickness The Core • high density of nickel (Ni) and iron (Fe) • diameter: ~ 2200 miles • temperatures: 4000o-10,000o F.

5. The Mantle • predominantly (but not completely) rigid • solid with plastic qualities • contains large amounts of the elements silicon (Si), iron (Fe), and magnesium (Mg) • measures 1700-1800 miles thick

6. The Crust • brittle zone • varies in thickness from 6-40 miles; thickest in the mountains and thinnest in the ocean basins

7. The Crust • brittle zone • varies in thickness from 6-40 miles; thickest in the mountains and thinnest in the ocean basins

9. Plate Tectonics: A Theory • Plate Tectonics: A theory that attempts to explain massive crustal re-arrangment based on the movement of continent sized lithospheric plates.

10. Plate Tectonics: A Theory • Plate Tectonics: A theory that attempts to explain massive crustal re-arrangment based on the movement of continent sized lithospheric plates. • Theory of Continental Drift • Proposed by Alfred Wegner in 1915

11. Plate Tectonics: A Theory(and a Proof by the Prof ) To “prove” the theory of plate tectonics I must • prove that Pangea existed (what was here before this) • provide a mechanism (motor) for change • provide a structure that would allow for change • connect all three points above to large scale changes on the Earths surface

12. Homework: Read pgs 247Be prepared to tell me what the Lithosphere and asthenosphere are.

13. SWBAT provide evidence that Pangea existed IOT help prove the theory of Plate Tectonics • Drill: Label the arrows with either the Lithosphere or the Asthenosphere

14. Pangaea: The Greatest Grandaddy of ‘em all About 200 million years ago the continents were all connected into 1 super continent called PANGEA (which means "all earth").

17. Pangea: The Greatest Grandaddy of ‘em all Until recently this was just a theory without any practical or empirical evidence. However, evidence for the movement of crustal/lithospheric plates can be found in: [1] the "fit" of the continents [2] fossil evidence on opposite coastlines [3] rock types and structural similarities [4] paleoclimatic evidence [5] paleomagnetic evidence

18. Evidence of Pangea (The First Part of the Proof by the Prof) 1. “The Fit of The Continents”

19. Evidence of Pangea (The First Part of the Proof by the Prof) 2. Fossil Evidence on Opposite Coastlines • Animal Fossils • Cynognathus • Mesosaurus • Lystrosaurus • Plant Fossils • Glossopterix

20. Cynognathus was a meter-long predator of the Lower Triassic.Fossils have so far been recovered from South Africa, South America, China and Antarctica.

21. Evidence of PangeaFossil Evidence

22. Early aquatic relative of reptiles, found as fossils from the Early Permian Period (299 million to 271 million years ago) in South Africa and South America. Roughly 1 meter long

23. Evidence of Pangea Fossil Evidence

24. AGE:Early Triassic, 240 million years agoSIZE:Adults about 1 meter longMEANING OF NAME:'Shovel reptile'Lystrosaurus has long been known from many parts of the ancient megacontinent Gondwana, although it has yet to be found in Australia. It is known, for example, in Antarctica, India, and Africa. In recent decades it has been found in Russia, China and Mongolia. This may be the result of movement of animals from Gondwana across the large landmass of northern and southern continents combined Pangaea, at the time Lystrosaurus lived.

25. Evidence of Pangea Fossil Evidence

27. Evidence of Pangea Fossil Evidence

28. Evidence of Pangea Fossil Evidence

30. Evidence of Pangea (The First Part of the Proof by the Prof) 3. Rock Types and Structural Similarities

31. Evidence of Pangea (The First Part of the Proof by the Prof) 4. Paleoclimatic Evidence - evidence of ancient climates

32. Evidence of Pangea (The First Part of the Proof by the Prof) 5. “Paleomagnetic Evidence

35. The map illustrates the types of plate boundaries and the directions of plate movements. Note the examples given for the locations of each type of plate boundary and the consequences of plate movement along these boundaries.

36. A Structure to Build On (The Third Part of the Proof by the Prof)

37. A Structure to Build On:The First Step • 1909: Andrija Mohorovicic presented the first concrete evidence for the layering of the earth • the velocity of seismic waves increased abruptly at approx. 50 km. below the surface of the earth • coincides with the break between the crust and the mantle • indicates a significant change in the mineral composition of the earth • This boundary layer separates the crust from the mantle and is known as the MOHOROVICIC DISCONTINUITY. For ease this is often shortened to the MOHO.

38. A Structure to Build On:The First Step

39. The Lithosphere and the Asthenosphere In addition to the "crust" and the "mantle" there are 2 very important zones called the asthenosphere and thelithosphere. The lithosphere includes the upper mantle and the crust of the earth glides over the underlying asthenosphere. 2. The asthenosphere is a partially molten region which has plastic characteristics

40. The Lithosphere and the Asthenosphere In addition to the "crust" and the "mantle" there are 2 very important zones called the asthenosphere and the lithosphere. The major difference: • the lithosphere is brittle and therefore cracks and breaks • the asthenosphere is plastic and deforms without breaking.

41. The Lithosphere • The lithosphere is a combination of the oceanic and continental crusts moving over the molten asthenosphere. • The lithosphere is composed of 15 major plateswhich are sliding against each other, colliding, or drifting apart.

43. The Asthenosphere

44. The Plates: Ocean vs. Continent • If we focus for a moment on the lithosphere we can isolate two types of crustal material: oceanic crust and continental crust

45. The Plates: Ocean vs. Continent • Continental Crust • composed predominantly of the elements Silicon(Si) and Aluminum (Al) • SG = 2.7 (more on this in a moment) • Ocean Crust • composed predominantly of the elements Silicon (Si) and Magnesium (Mg) • SG = 3.0

46. Specific Gravity • Specific gravity: the ratio of the weight of a given volume of material to the weight of an equal volume of water • The differences in specific gravity will be important when we discuss the process ofsubduction.

47. We’re Outta Here (or how the Big Kahuna Moved On)(a.k.a.:The Second Part of the Proof by the Prof) • As we stated previously the lithosphere is composed of 13 plates which are sliding against each other, colliding, or drifting apart. • The question is: How are the lithospheric plates moving?

48. Objective: SWBAT identify the three theories of movement IOT prove the theory of plate tectonics • Drill: What evidence do we have that Pangaea Existed

49. Three Possible Theories of Movement (The Second Part of the Proof by the Prof) • there are huge convectional currents emanating from the core which carry the lithospheric plates • convection cells confined to the upper mantle which move the lithospheric plates, and • hot, thermal plumes which confine the rise of heated material to certain areas below the earth which drive plates apart.

50. Three Possible Theories of Movement • there are huge convectional currents emanating from the core which move the lithospheric plates