Chapter 4 igneous rocks formation 20122013

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Brought to you by teachers of Cobb County, Thanks! Modifications have been made to the show. Students will classify rocks based on process of formation

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Chapter 4 igneous rocks formation 20122013

  1. 1. Rock ClassificationRocks are divided into three main classes based on how they form:1. Igneous2. Sedimentary3. MetamorphicEach type of rock can be further classified based on: Composition and texture
  2. 2. Composition Thechemical make up of the rock or what it is made of. This can be minerals or other materials: shells, clay, plants, sand, pebbles
  3. 3. Texture/Grains Determined by the grains size, shape and position. Igneous can be fine or coarse grain Sedimentary can be characterized by observing lithified (cemented) inorganic grains, minerals, organic material, or fossil fragments. The wide range of textures common in sedimentary rocks is separated into clastic , chemical, and bioclastic (biochemical) groups.
  4. 4. Texture/Grains Metamorphic textures consist of two main types: foliated and non-foliated textures. Texture can reveal the process that formed the rock.
  5. 5. Igneous Rocks
  6. 6. What are they? Rock made from cooled – LAVA, above ground or – MAGMA, below ground.
  7. 7. Classification They are classified in 3 ways:1. Texture – grain2. Origin - where formed3. Mineral Composition – made from
  8. 8. Grain Size Have….SPECIAL NAMES
  9. 9. Texture/Grain Coarse Grained = large grains, cooled slowly Think about it…. If it cools over a long time – the grains have time to get big! Most abundant intrusive rock is GRANITE Fine Grained = small grains, cooled fast Think about it… If it cools over a short time – the grains don’t have time to get big! Basalt
  10. 10. Igneous Rock Formation-Origin Extrusive – formed ABOVE GROUND. It cools fast so it has small grains. Intrusive – formed UNDERGROUND. It cools slowly so it will have large grains. Laccolith
  11. 11. Examples of each type ofROCKFine GrainedBasalt = Extrusive Igneous rockCourse GrainedGranite = Intrusive Igneous rock
  12. 12. Mineral Composition How much silica is in the magma/lava? – Low silica content = dark colored = Mafic – High silica content = light colored = Felsic High Silica Content Low Silica Content Felsic Igneous Rock Mafic Igneous Rock
  13. 13. Big Crystals Small or No Crystals Lighter Darker
  14. 14. Label the igneous rock formation
  15. 15. Ticket out: CHOOSE ONLY ONE What makes up the grains in an igneous rock?Illustrate grains of an igneous rock and explain why this happensCompare and contrast intrusive and extrusive igneous

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