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The Earth System: Solid Earth

The Earth System: Solid Earth. Objectives. Describe the size and shape of Earth. Describe the compositional and structural layers of Earth’s interior. Identify the possible source of Earth’s magnetic field. Summarize Newton’s law of gravitation. Mt St Helens. Earth Basics.

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The Earth System: Solid Earth

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  1. The Earth System: Solid Earth

  2. Objectives • Describe the size and shape of Earth. • Describe the compositional and structural layers of Earth’s interior. • Identify the possible source of Earth’s magnetic field. • Summarize • Newton’s law of gravitation. • Mt St Helens

  3. Earth Basics • Earth formed about 4.6 billion years ago • Approximately 70% of Earth’s surface is water • We have gained a greater understandingof Earth’s interior by studying seismic waves (vibrations caused by earthquakes), which travel through the Earth.

  4. Crust – continental crus on top of oceanic crust Mantle – has convection currents of molten rock) Temperature, pressure, and density increase with depth.  Outer Core – liquid nickel and iron Inner Core – solid nickel and iron Earth Basics Crust Mantle Core Drawing not to scale

  5. Layers Defined by Composition • Crust – the thin, rocky outer layer of Earth; it is divided into oceanic and continental crust

  6. Continental crust is 15-80km thick and composed of granite Crust Oceanic crust is 5-10km thick and composed of basalt

  7. The Mantle Mantle – thick, rocky, and viscous (semi-fluid) region; approximately 82% of Earth’s volume is in the mantle

  8. The Core • Core:central part consists of two parts: • outer core – liquid portion of Earth made of molten metal, primarily nickel and iron (reason we have a magnetic field) • inner core – dense ball of solid metal

  9. Structural Zones of Earth’s Interior • Guess what? Two more zones to remember! • Lithosphere: solid, outer layer of Earth which consists of the crust and the solid upper portion of the mantle (15-300km thick) • Asthenosphere: viscous, semi-fluid layer beneath the lithosphere; made of molten rock which flows and allows tectonic plates to move on top of it (200km thick) • Earth Song

  10. Magnets and Earth’s Magnetic Field • All magnets have two areas of strongest force, called poles. • Each magnet has one north pole and one south pole. • Like poles repel, and opposite poles attract. • The magnetic region where you can “feel the force” is called a magnetic field.

  11. magnetic north pole geographic north pole magnetic south pole geographic south pole Motions within Earth’s outer core produce electric currents which create Earth’s magnetic field. Magnetic lines of force around the earth are like those around a giant magnet. The magnetic north pole and the geographic north pole are not located in the same place! The north pole of a compass points to the earth’s magnetic north pole. The Earth is a magnet!

  12. Earth’s Four Spheres: The Hydrosphere • Hydrosphere: portion of Earth consisting of water • Covers 70% of Earth’s surface. • Exists in the form of oceans, lakes, rivers, streams, glaciers, ice sheets, and groundwater.

  13. The Geosphere • Geosphere:the mostly solid, rocky part of Earth • Includes all of the rock and soil on the surface of continents and ocean floor. • Also includes the solid and molten interior of Earth • Geosphere contains other spheres like the pedosphere: soil

  14. The Biosphere and Atmosphere • Biosphere: portion of Earth where life exists • Composed of all of the forms of life in the geosphere, hydrosphere, and atmosphere • Atmosphere: layer of gases surrounding and retained by gravity

  15. Cryosphere • Cryosphere: portions of the Earth’s surface where water is in solid form • Includes sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground • Most of the world’s ice volume is in Antarctica

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