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Earth’s Interior Structure

Earth’s Interior Structure. -heavy elements sunk and lighter ones stayed near the surface. According to scientists, what happened during the IRON CATASTROHE?. The Crust - silicate rocks, primarily granite and basalt Oceanic Crust - mostly basalt

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Earth’s Interior Structure

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  1. Earth’s Interior Structure

  2. -heavy elements sunk and lighter ones stayed near the surface According to scientists, what happened during the IRON CATASTROHE? • The Crust- silicate rocks, primarily granite and basalt • Oceanic Crust - mostly basalt • Continental Crust - igneous, metamorphic, and sedimentary rocks • The Mantle - iron and magnesium rich silicate rocks • Upper Mantle • Lower mantle • The Core - iron nickel alloy • Outer core • Inner core Crust about 60 miles thick Mantle is about 1900 miles thick The core is about 1500 miles thick

  3. A trend in the earth's interior Deeper ===> find higher density materials This is the result of differentiation -- a process driven by gravity. When a planet is young and hot enough to be semi-molten, denser materials (shown in black) sink to the center and lighter materials float higher up. As the planet cools, it solidifies but can be left with a hot, molten (or solid) metallic core and a surface of relatively low density, light rock (the crust) "floating" on a thick semi-molten zone (the mantle).

  4. The Mantle has three parts….. The topmost layer is the lithosphere, which is comprised of the crust and solid portion of the upper mantle The lithosphere essentially floats atop a semi-liquid layer known as the asthenosphere. This layer allows the solid lithosphere to move around since the asthenosphere is much weaker than the lithosphere. The mesosphere is below the ansthensphere and is composed of stiffer rock….extends to the outer core

  5. The core region is very hot, about 6500K (warmer than the surface of the sun!). The core is largely liquid metal, but the high pressure makes the inner core turn to solid despite the high temperature. The heat is a combination of energy trapped at the time of formation and energy released by radioactive decay.

  6. Radio Active Decay (Heats the Earth) Many nuclei are radioactive This means they are unstable, and will eventually decay by emitting a particle, transforming the nucleus into another nucleus, or into a lower energy state. A chain of decays takes place until a stable nucleus is reached There are three common types of radioactive decay, alpha, beta, and gamma. The difference between them is the particle emitted by the nucleus during the decay process.

  7. Alpha decay In alpha decay, the nucleus emits an alpha particle; an alpha particle is essentially a helium nucleus, so it's a group of two protons and two neutrons. A helium nucleus is very stable

  8. What is happening here?

  9. Beta decay A beta particle is often an electron. If an electron is involved, the number of neutrons in the nucleus decreases by one and the number of protons increases by one

  10. Gamma decay The third class of radioactive decay is gamma decay, in which the nucleus changes from a higher-level energy state to a lower level Gamma rays are very penetrating; they can be most efficiently absorbed by a relatively thick layer of high-density material such as lead

  11. Electron Capture Electron Capture--this is a process where an electron loses its energy that keeps it in an energy level, and gets pulled into the nucleus. This is a type of fusion

  12. The Core….. THERMODYNAMICS 101 SAYS….. Hot liquid metal spinning will produce an electric current and thus creates EARTH’S MAGNETIC FIELD. But how do we know?

  13. How do we KNOW what the interior of earth is composed of? WE USE SEISMIC WAVES!!! Compressional waves, also known as primary or P waves, travel fastest, at speeds between 1.5 and 8 kilometers per second in the Earth's crust. Shear waves, also known as secondary or S waves, travel more slowly, usually at 60% to 70% of the speed of P waves. Compressional P waves will travel and refract through both fluid and solid materials. Shear S waves, however, cannot travel through fluids like air or water. Fluids cannot support the side-to-side particle motion that makes S waves.

  14. Study how these seismic waves are traveling thru the Earth At larger distances, some P waves that travel through the liquid core (path K on the figure above) would arrive, but still no S waves. The Earth has to have a molten, fluid core to explain the lack of S waves in the shadow zone, and the bending of P waves to form their shadow zone.

  15. The Earth's surface and its inhabitants are protected from dangerous cosmic radiation (energetic protons) from the Sun by the Earth's magnetic field.

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