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Plate Tectonics
The document outlines the structure of the Earth, detailing its layers and the theory of plate tectonics, which explains the movement of tectonic plates and the landforms created by this movement. It discusses the differences between oceanic and continental crust, the processes leading to earthquakes, volcanoes, and mountain formation, and the evidence supporting plate tectonics. Key concepts include subduction, sea floor spreading, and the historical context of continental drift and magnetic patterns in rocks.
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Plate Tectonics
- 2. Describe andDraw the Earth’s Structure Explain the Earth’s structure – the different layers Explain the Theory of Plate Tectonics Understand how plate tectonics creates landforms around the world.
- 5. The crustis the thin, outer part of the Earth. The crust is divided into a number of sections called plates that float on the molten mantle below The movement of the plates causes Earthquakes, fold mountains and volcanoes. The plates move because of convection currents in the mantle underneath
- 7. Oceanic (young) ◦6 – 12K thick ◦ Dense heavy rocks (usually basalt) ◦ Silicon and Magnesium rich rocks (SIMA) Continental (older) ◦ 40 – 60 K thick ◦ Lighter rocks (granite, limestone etc) ◦ Silicon and Aluminium rich rocks (SIAL)
- 9. This isthe study of the processes that cause the movement of the Earth’s plates and the landforms that result. Plate Tectonics is a mixing of two theories ◦ Continental Drift by Alfred Wegener ◦ Sea Floor Spreading by Harry Hess
- 11. •Fossils of sameanimal species on different continents •Matching rock types and mountain trends on different continents •Matching coastline shape (Africa and S. America)
- 12. As new magmais pushed up from the mantle, it pushes the crust to either side to make space. This causes the sea floor to spread apart.
- 13. North American Plate EurasianPlate Newly formed crust
- 14. Different magneticpatterns on rocks either side of the mid ocean ridges match up Youngest rocks are nearest the mid ocean ridge Youngest islands are nearest the ridge (e.g. Iceland) – older Islands (e.g. Ireland) are further away
- 16. The Earth’sNorth and South magnetic poles have reversed several times in Earth’s history Grains of iron in lava point toward the magnetic pole as it cools – keeping a record of the magnetic field at the time The ideas of Continental Drift and Sea Floor Spreading were merged in the 1960s to form the Theory of Plate Tectonics by Vine and Matthews
- 19. Oceanic –Continental plate collisions form... ◦ trenches ◦ Earthquakes ◦ Fold mountains and volcanoes ◦ Terranes (piles of sedimentary material at plate boundaries) Key Term: Subduction (one plate pushed under another) Volcanic eruptions at these boundaries are often very violent
- 20.
- 21. Oceanic –Oceanic plate collisions form... ◦ Trenches ◦ Island Arcs – lines of volcanic islands (e.g. Japan and its islands) ◦ Earthquakes
- 23. SIAL How platesmove Basalt Mantle-Crust boundary Harry Hess Fold Mountains Convection Constructive plate boundary Fossils Silicon-Aluminium Pangaea Proof of continental drift Granite Oceanic Plate Rock Moho Sea Floor Spreading Mid Atlantic Ridge Continental Plate Rock Himalayas One big “Super Continent”
- 24. Example of wherethis is found: Mid Atlantic Ridge & Iceland
- 25. Proof of SeaFloor Spreading – the youngest crust is closest to the Mid Atlantic Ridge
- 26. Two plates scrape pasteach other. What will happen here? Example of a Transverse Plate Boundary?
- 31. Hotspots – formedwhen a plume of rising magma in the middle of a plate forces its way through to the surface. Produces gentle volcanic eruptions as the magma is not under pressure.