ChapC2.2

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Rocks

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ChapC2.2

  1. 1. Types of Rocks
  2. 2. Igneous Rock <ul><li>rock: a material made up of one or more minerals </li></ul><ul><ul><li>rocks are not crystals - minerals are crystals </li></ul></ul><ul><ul><li>some rocks form at or near Earth’s surface </li></ul></ul><ul><ul><li>some rocks form deep in the crust - in the Earth’s middle layer (mantle) </li></ul></ul><ul><li>rocks are classified into 3 groups based on how they are formed </li></ul>
  3. 3. <ul><li>igneous rock: rocks that forms when melted rock hardens </li></ul><ul><ul><li>lava is melted rock that reaches Earth’s surface </li></ul></ul><ul><ul><li>lava cools and hardens quickly </li></ul></ul><ul><ul><ul><li>large mineral pieces do not have time to form </li></ul></ul></ul><ul><ul><ul><li>rocks formed from lava have small mineral pieces and are called fine-grained </li></ul></ul></ul>
  4. 4. <ul><li>magma: melted rock below Earth’s surface </li></ul><ul><ul><li>magma cools and hardens slowly </li></ul></ul><ul><ul><li>minerals can form large grains that are easy to see </li></ul></ul><ul><ul><li>rocks formed from magma are called coarse-grained </li></ul></ul>
  5. 5. <ul><li>basalt is the most common igneous rock </li></ul><ul><ul><li>forms from lava at Earth’s surface </li></ul></ul><ul><ul><li>dark, greenish-black rock </li></ul></ul><ul><ul><li>made of minerals feldspar and pyroxene </li></ul></ul><ul><li>gabbro is an igneous rock made of feldspar and pyroxene </li></ul><ul><ul><li>has larger mineral grains </li></ul></ul><ul><ul><li>forms inside Earth instead of at surface </li></ul></ul>basalt gabbro
  6. 6. <ul><li>pumice : another igneous rock </li></ul><ul><ul><li>tiny holes in pumice caused from gases escaping from lava as it cools </li></ul></ul><ul><ul><li>feels rough and scratchy </li></ul></ul><ul><li>obsidian : forms from lava </li></ul><ul><ul><li>lava cools so quickly that rocks look like black glass </li></ul></ul><ul><ul><li>when it breaks sharp edges form </li></ul></ul><ul><li>granite : common igneous rock </li></ul><ul><ul><li>forms when magma cools slowly beneath Earth’s surface </li></ul></ul><ul><ul><li>made of large grains of feldspar, quartz, and mica </li></ul></ul>
  7. 7. GRANITE OBSIDIAN PUMICE
  8. 8. Sedimentary Rock <ul><li>weathering: how rocks are broken down into smaller pieces </li></ul><ul><ul><li>wind, water, ice, and plant roots cause weathering </li></ul></ul><ul><li>rocks weathered into small pieces and moved to other places by wind, water, gravity, or slow moving glaciers </li></ul><ul><ul><li>erosion: movement of weathered rock pieces from one place to another </li></ul></ul>
  9. 9. <ul><li>erosion caused by water - over time rock pieces drop to lake, river, stream bottoms </li></ul><ul><ul><li>this material is sediment </li></ul></ul><ul><li>layers of sediment form sedimentary rock because all the layers squeezed and get stuck together </li></ul><ul><li>conglomerate is a type of sedimentary rock </li></ul><ul><ul><li>pieces can be big as boulders or small as peas </li></ul></ul><ul><ul><li>pieces are round and smooth </li></ul></ul><ul><ul><li>form in shallow water </li></ul></ul>
  10. 10. <ul><li>smaller sediments are carried farther and dropped later </li></ul><ul><ul><li>siltstone is a rock made of smaller sediments </li></ul></ul><ul><li>limestone : fine-grained sedimentary rock </li></ul><ul><ul><li>made of mostly mineral calcite </li></ul></ul><ul><ul><li>forms in oceans </li></ul></ul><ul><ul><ul><li>sometimes from seashells </li></ul></ul></ul><ul><ul><li>a few form in lakes </li></ul></ul>
  11. 11. <ul><li>sandstone another kind of sedimentary rock </li></ul><ul><ul><li>made of bits of rock and minerals the size of sand grains </li></ul></ul><ul><ul><li>nearly all sandstone is made of mostly the mineral quartz </li></ul></ul><ul><ul><li>some sandstone are fine-grained </li></ul></ul><ul><ul><ul><li>feel smooth when you touch them </li></ul></ul></ul><ul><ul><li>some sandstone are coarse-grained </li></ul></ul><ul><ul><ul><li>feel rough against skin </li></ul></ul></ul><ul><ul><li>can form on land or in water </li></ul></ul>
  12. 12. <ul><li>shale : fine-grained sedimentary rock </li></ul><ul><ul><li>made of small sediments </li></ul></ul><ul><ul><li>sediments so small that you can only see them with a magnifying glass or microscope </li></ul></ul>
  13. 13. Metamorphic Rocks <ul><li>metamorphic rocks: rocks that were changed due to high heat and pressure </li></ul><ul><ul><li>texture (the way a rock looks and feels) and the minerals that make up the rocks are changed </li></ul></ul><ul><li>metamorphic rocks can form from any rock </li></ul><ul><ul><li>sedimentary, igneous, or other metamorphic rocks </li></ul></ul>
  14. 14. <ul><li>some metamorphic rocks form when mountains built up </li></ul><ul><ul><li>schist </li></ul></ul><ul><ul><ul><li>has wavy lines </li></ul></ul></ul><ul><ul><ul><li>splits into layers easily </li></ul></ul></ul><ul><ul><li>gneiss </li></ul></ul><ul><ul><ul><li>forms when schist is heated and squeezed more </li></ul></ul></ul><ul><ul><ul><li>has bands of light and dark minerals </li></ul></ul></ul>Schist Gneiss
  15. 15. <ul><li>marble is another metamorphic rock </li></ul><ul><ul><li>forms when limestone is squeezed and heated </li></ul></ul><ul><li>slate </li></ul><ul><ul><li>forms when shale is under great pressure </li></ul></ul><ul><ul><li>has layers </li></ul></ul><ul><li>quartzite </li></ul><ul><ul><li>forms from sandstone when heat melts the sand grains together </li></ul></ul><ul><ul><li>milky color </li></ul></ul><ul><ul><li>other minerals can give it a gray or pink color </li></ul></ul>
  16. 16. QUARTZITE SLATE MARBLE
  17. 17. Summary <ul><li>rocks are made up of one or more minerals </li></ul><ul><ul><li>classified by how they are formed </li></ul></ul><ul><li>igneous rocks form when magma or lava cools and hardens </li></ul><ul><li>sedimentary rocks made of pieces of rock that have been squeezed and stuck together </li></ul><ul><li>metamorphic rocks form when heat and pressure change rocks </li></ul>

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