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CHAPTER 7

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  1. CHAPTER 7 PLATE TECTONICS

  2. Structure of the Earth • file://\\hsa005\staff_docs$\wfrye\My Documents\Holt Middle\student\ch07\sec01\vc00\hz507_01_v00fs.htm

  3. SECTION 1 INSIDE THE EARTH

  4. LAYERS OF THE EARTH • CRUST • OUTERMOST LAYER OF THE EARTH • Thinnest • Least dense

  5. TYPES OF CRUST • CONTINENTAL • FELSIC • LESS DENSE • OCEANIC • MAFIC • MORE DENSE

  6. Chapter 7 Section1 Inside the Earth • There are two types of crust—continental and oceanic. Oceanic crust is thinner and denser than continental crust.

  7. MANTLE • LAYER BETWEEN THE CRUST & CORE • MOHOis the BOUNDARY BETWEEN CRUST AND MANTLE

  8. Of what are the layers made ? • CRUST is silicate (Quartz) • MANTLE is Olivine (Iron & Magnesium) • CORES are Iron and Nickel

  9. LITHOSPHER E • “ROCK SPHERE” • RIGID LAYER • TECTONIC PLATES

  10. ASTHENOSPHERE • “WEAK SPHERE” • TECTONIC PLATES FLOAT ON IT

  11. MESOSPHERE • STRONG PART OF THE MANTLE • “MIDDLE SPHERE”

  12. cores • OUTER CORE • LIQUID LAYER • INNER CORE • SOLID, DENSE CENTER OF THE EARTH

  13. Tectonic Plates and Plate Tectonics file://\\hsa005\staff_docs$\wfrye\My Documents\Holt Middle\student\ch07\sec01\vc01\hz507_01_v01fs.htm

  14. Seismic Waves: Surface Waves • file://\\hsa005\staff_docs$\wfrye\My Documents\Holt Middle\student\ch07\sec01\vc02\hz507_01_v02fs.htm

  15. Seismographs and Mapping Earth's Layers • file://\\hsa005\staff_docs$\wfrye\My Documents\Holt Middle\student\ch07\sec01\vc03\hz507_01_v03fs.htm

  16. TECTONIC PLATES • PIECES OF THE LITHOSPHERE THAT MOVE AROUND ON THE ASTHENOSPHERE • LOOK LIKE “JIGSAW PUZZLE PIECES”

  17. The PLATES • CONTAIN CONTINENTAL, OCEANIC, & SOMETIMES BOTH TYPES OF CRUST • CONTINENTAL IS THICKER THAN OCEANIC • CONTINENTAL HAS “ROOTS” LIKE ICEBERGS

  18. PACIFIC NORTH AMERICAN COCOS NAZCA SOUTH AMERICAN AFRICAN EURASIAN INDIAN AUSTRALIAN ANTARCTIC 10 MAJOR PLATES

  19. All oceanic crust • PACIFIC • COCOS • NAZCA

  20. Chapter 7 Section1 Inside the Earth

  21. Both oceanic and continental • NORTH AMERICAN • SOUTH AMERICAN • AFRICAN • EURASIAN • INDIAN • AUSTRALIAN • ANTARCTIC

  22. How do we know what the interior is like? • Studied SEISMIC WAVES – which are vibrations traveling through the Earth • They travel at different speeds

  23. Different seismic wave speeds • ROCK > FAST (more dense) • LIQUID > SLOW (less dense)

  24. How fast does a seismic wave travel? • 7 - 8km/s in crust • 8 - 10km/s in mantle • 11 – 12km/s in core

  25. Relative speeds of some things: • Speed of sound in: • Air - .35km/s • Water - .70km/s • 747 - .18km/s • Bullet - .5km/s • Space Shuttle – 7.8km/s

  26. Deepest hole ever drilled? • Finished in 1984 – took 24 years • Kola Peninsula, Russia • 12,226m

  27. SECTION 2 RESTLESS CONTINENTS

  28. Continental Drift (Pangaea) • file://\\hsa005\staff_docs$\wfrye\My Documents\Holt Middle\student\ch07\sec02\vc00\hz507_02_v00fs.htm

  29. THEORY OF CONTINENTAL DRIFT • ALFRED WEGENER • CONTINENTS DRIFT APART FROM ONE ANOTHER • HOW – driving force is CONVECTION CURRENTS

  30. EVIDENCE FOR CONTINENTAL DRIFT • PUZZLE FIT OF CONTINENTS • FOSSILS OF PLANTS & ANIMALS

  31. Fossil links

  32. Dinosaur Cove

  33. EVIDENCE FOR CONTINENTAL DRIFT • SIMILAR ROCK TYPES • CLIMATE PATTERNS • GLACIAL GROOVES • Coal beds similar around the world

  34. PANGAEA • CONTINENTS WERE ONE LARGE LANDMASS CALLED PANGAEA • BROKE INTO 2 LANDMASSES

  35. PANGAEA • LAURASIA • North • GONDWANA • South • PANTHALASSA • ONE LARGE OCEAN

  36. SEA-FLOOR SPREADING • PROCESS BY WHICH NEW OCEAN CRUST IS CREATED

  37. Sea-Floor Spreading • file://\\hsa005\staff_docs$\wfrye\My Documents\Holt Middle\student\ch07\sec02\vc01\hz507_02_v01fs.htm

  38. SEA-FLOOR SPREADING • MID-OCEAN RIDGES • Occur on both sides of the “rift” • EX. MID-ATLANTIC RIDGE

  39. SEA-FLOOR SPREADING • CRUST INCREASES IN AGE AWAY FROM THE MID-OCEAN RIDGE

  40. MAGNETIC REVERSAL • EARTH’S MAGNETIC POLE CHANGES PLACE • EVIDENCE FOR SEA-FLOOR SPREADING

  41. Magnetic Reversals and Sea-Floor Spreading • file://\\hsa005\staff_docs$\wfrye\My Documents\Holt Middle\student\ch07\sec02\vc02\hz507_02_v02fs.htm

  42. MAGNETIC REVERSAL • MID-OCEAN RIDGES CONTAIN MAGNETIC MINERALS

  43. MAGNETIC REVERSAL • MAGNETIC MINERALS RECORD THE EARTH’S MAGNETIC FIELD

  44. Which layers are the same age?