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Structure of the Earth and the Rock Cycle

Structure of the Earth and the Rock Cycle. Lithosphere composed of minerals. Definition of “ Mineral” ?. Silicate minerals. 92% of crust silicon and oxygen. A rock is a natural solid substance made up of minerals rocks classified by origin : 3 types. Types of Rocks. 1. IGNEOUS

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Structure of the Earth and the Rock Cycle

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  1. Structure of the Earth and the Rock Cycle

  2. Lithosphere composed of minerals • Definition of “Mineral” ?

  3. Silicate minerals • 92% of crust • silicon and oxygen

  4. A rock is a natural solid substance made up of minerals • rocks classified by origin : 3 types

  5. Types of Rocks 1. IGNEOUS • molten rock that has cooled and solidified • molten rock is magma or lava a) INTRUSIVE • cools below surface; big crystals; coarse b) EXTRUSIVE • cools at surface; fine

  6. Fine-textured extrusive Coarse-textured intrusive Glassy; rapid cooling

  7. Basalt with vesicles

  8. extrusive

  9. intrusive

  10. Mafic and felsic igneous rock • Felsic: mostly felsic minerals • High in feldspar and silicate minerals • Lighter • Less dense • Mafic: mostly mafic minerals • High in magnesium and iron • Darker • Denser • Ultramafic: all mafic minerals

  11. 2. SEDIMENTARY • made up of sediments that have been compacted and cemented. • sediments: all solid particles transported by water, ice, wind, gravity • mud, sand, shells, debris, dust, rock fragments • mudstone, sandstone, limestone, conglomerate, shale • accumulate in strata (layers)

  12. mudstone

  13. sandstone

  14. limestone

  15. conglomerate

  16. strata

  17. 3. METAMORPHIC • altered from original rock by heat, pressure or chemical activity • began as igneous, sedimentary, or metamorphic rock • shale --> slate • slate --> schist • granite --> gneiss • limestone --> marble

  18. gneiss schist

  19. slate

  20. Rock Cycle

  21. Structure of Earth

  22. Core • Mantle • Crust

  23. Core • Inner • 5150 – 6370 km (below surface) • Solid iron • 5400 – 9000 degrees F • Outer • 2900 – 5150 km • Molten iron

  24. Core • Mantle • Crust

  25. Lower mantle • Upper • Uppermost

  26. Lower mantle • very dense; iron and magnesium • 670 – 2900 km • Upper mantle • rigid at lower end • “plastic” toward crust: asthenosphere • 250 -670 km • Uppermost mantle • Rigid • “Moho” to 70 km

  27. “Moho” • Mohorovičić discontinuity • Boundary between crust and mantle • Change in seismic waves here

  28. Core • Mantle • Crust

  29. Crust • continental : 25 miles thick • Lower mafic; upper felsic (granite) • Less dense • oceanic: 5-6 miles thick • Mafic (basalt) • More dense • Lithosphere = uppermost mantle and crust • Rigid • ultramafic

  30. Lithosphere is divided into large plates • rigid plates “float” on the plastic asthenosphere, just deep enough to support their own weight: • Isostasy

  31. Isostatic adjustment of crust: • add weight (sediment, glacial ice): crust will sink • remove weight (erosion, glacial ice melts): crust will rebound

  32. ice Crust rebound Crust sank Duluth Northeast “drowned “ St. Louis River

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