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Earth’s Interior

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  1. Earth’s Interior Direct evidence – rock samples from up to 12km deep 2. Indirect evidence – seismic waves (waves that travel through the earth during earthquakes)

  2. Temperature and Pressure Temperature • Deeper you go the warmer it is • After 20 meters, every 40 meters you descend the temperature rises 1 degree Celsius • High temperature results from the formation of the planets and radioactive substances releasing energy Pressure • The deeper you go, the higher or greater the pressure


  4. Layers of the Earth • Crust: layer of solid rock that includes both dry land and ocean floor a) oceanic crust – crust beneath the ocean, made of basalt rock b) continental crust – the crust that forms the continents (land), made of granite

  5. Layers of the Earth • Mantle: below the crust, very hot and solid, 3,000 km thick a) lithosphere: uppermost mantle and crust, pushed together, 100km thick b) asthenosphere: soft layer of the mantle (it can bend like plastic) but is still solid, the lithosphere floats on top of this layer, 2,767km thick c) lower mantle: beneath the asthenosphere, solid layer that extends to the core

  6. Layers of the Earth 3. Core – two parts made of iron and nickel a) outer core: layer of molten metal that surrounds the inner core, this layer is liquid b) inner core: solid metal due to extreme pressure. - The movement in the core creates Earth’s magnetic field

  7. Convection and the Mantle Types of Heat Transfer • Radiation: transfer of energy through space, no direct contact needed. Example: sun  blacktop or heat from fire • Conduction: heat transfer within a material or between materials that are touching (soup spoon in soup pot) • Convection: heat transfer by the movement of currents within a fluid (bounce off one another and heat up, example: teapot). - caused by differences in temperature and density within a fluid

  8. Convection currents: the flow that transfers heat within a fluid • Gravity and density put these currents in motion * Convection currents occur in the mantle and outer core *

  9. Continental Drift • It states: that all the continents were once joined together in a single landmass and have since drifted apart • Alfred Wegener responsible for this idea • When all continents were joined together it was called Pangaea • Wegener used evidence from land features, fossils, and climate change to prove this theory (it was NOT accepted) Land: used mountains and features on the continents Fossils: any trace of an ancient organism preserved in rock Climate change: as a continent moves toward the equator, it becomes warmer (coal was found in Antarctica)

  10. Sea-floor Spreading • Sea-floor spreads apart along both sides of a mid-ocean ridge as new crust is added • Ocean (sea) floor moves like a conveyor belt, carrying the continents along with them

  11. Mid-ocean ridge: a mountain chain at the bottom of the ocean where the new ocean is produced. - The new ocean floor forms when lava is erupted onto the ocean floor.

  12. Evidence of Sea-Floor spreadingHarry Hess’s theory • Molten material: tube shaped rocks from molten material hardening quickly • Magnetic stripes: pattern of magnetized stripes (iron in the rock), when rock cools • Drilling samples: rock samples farther away from mid-ocean ridge the older the rock was

  13. Subduction and Trenches Deep ocean trench: deep underwater canyon that bends downward into the oceanic crust Subduction: when the ocean floor sinks beneath a deep ocean trench and back into the mantle

  14. How has this changed our oceans? • Pacific Ocean is shrinking because the deep ocean trenches are too big • Atlantic Ocean is getting bigger because it only has a few short trenches

  15. Plate Tectonics Plates: broken sections in the lithosphere that look like cracks Plate tectonics: pieces of Earth’s lithosphere are in slow, constant motion, driven by convection currents in the mantle • This theory explains the formation, movement, and subduction of Earth’s plates • As plates move, they collide, pull apart, or grind past one another

  16. Plate Boundaries Divergent boundary: place where 2 plates move apart. Example – Great Rift Valley or how the Grand Canyon Looks (don’t forget the Grand Canyon was formed by erosion) • Occur along mid-ocean ridges • Forms a rift valley (deep valley on land)

  17. Convergent Boundary Definition: place where two plates come together or collide • The more dense (heavier) plate will sink below the other plate (subduction) • On land this creates mountain ranges

  18. Transform Boundary Definition: place where two plates slip past one another in opposite directions *Earthquakes occur here*