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Igneous Rocks

Igneous Rocks. What is an igneous rock?. Born from fire Any rock that forms from magma or lava Most contain mineral crystals. Characteristics of Igneous Rocks. Classified according to their… Origin Texture Mineral composition. Origin.

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Igneous Rocks

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  1. Igneous Rocks

  2. What is an igneous rock? Born from fire Any rock that forms from magma or lava Most contain mineral crystals

  3. Characteristics of Igneous Rocks • Classified according to their… • Origin • Texture • Mineral composition

  4. Origin • Extrusive Rock- formed from lava that erupted onto Earth’s surface (ex. Basalt) • Intrusive Rock- igneous rock that formed when magma hardened beneath Earth’s surface (ex. Granite)

  5. Basalt Granite

  6. Texture • Fine-grained • Coarse-grained • Glassy • porphyritic

  7. Fine-Grained • Rapid cooling lava • Small crystals • Extrusive rocks

  8. Coarse-Grained • Slow cooling magma • Large crystals • Intrusive rocks

  9. Porphyritic • Large crystals scattered on a background of much smaller crystals • Intrusive rocks cool in 2 stages- rate of cooling is changed from slow to fast

  10. Flow banding What is the texture of the rock?

  11. Mineral Composition • Lava that is low in silica- dark colored rocks • Magma high in silica- light colored rock

  12. Uses of Igneous Rocks • Igneous rocks are hard, dense, and durable so they are used for • Tools • Building materials • Granite- long history of building material

  13. Sedimentary Rocks

  14. What is a sedimentary rock? • Composed of sediments derived from pre-existing rocks or by the crystallization of minerals that were held in solutions • Sediment- small, solid pieces of material that come from rocks or living things • Can include fossils, leaves, etc.

  15. How do the sediments turn into a rock? • Erosion • Deposition • Compaction • Cementation

  16. Erosion • Water, wind, or ice loosen and carry away fragments of rock

  17. Deposition • That’s when sediments stop traveling by water or wind and settle

  18. Compaction • Sediments fit loosely • Years go by…thick layers build up • Layers are heavy and press down • Compaction- process that presses sediments together (squeezes)

  19. Cementation • During compaction…minerals dissolve in water • Dissolved minerals crystallize and glue particles of sediments together • Whole process: millions of years

  20. http://www.classzone.com/books/earth_science/terc/content/visualizations/es0604/es0604page01.cfm?chapter_no=visualizationhttp://www.classzone.com/books/earth_science/terc/content/visualizations/es0604/es0604page01.cfm?chapter_no=visualization

  21. Types of Sedimentary Rocks • Clastic rocks • Organic rocks • Chemical rocks

  22. Clastic Rocks • Forms when rock fragments are squeezed together • Grouped by size of fragments & of which they are made • Ex. shale, sandstone, conglomerate and breccia

  23. Shale • Forms from tiny particles of clay • Thin, flat layers

  24. Sandstone • Forms from sand Contains holes- can absorb water

  25. Conglomerate & Breccia • Mixture of rock fragments of different sizes

  26. Organic Rocks • Remains of plants & animals are deposited in layers • Coal and limestone

  27. Coal • From remains of swampy plants

  28. Limestone • From hard shells of living things • Ex. chalk

  29. Chemical Rocks • Forms when minerals that are dissolved in a solution crystallize (ex. rock salt)

  30. Metamorphic Rocks

  31. What is a metamorphic rock? • A rock that has changed its form • Can change igneous, sedimentary, or other metamorphic rocks

  32. How do metamorphic rocks form? • Heat and pressure beneath Earth’s surface change rock • Its appearance, texture, crystal structure, and mineral content change

  33. Formation of Metamorphic Rocks • Earth’s plates push rock down toward mantle- HOT! • Magma also heats the rock • The deeper the rock is buried…the greater the pressure • Pressure and heat change minerals

  34. Formation of Metamorphic Rocks

  35. GRANITE Granite to Gneiss Gneissic granite – separation of dark & light minerals is just beginning Well banded gneiss

  36. Classifying Metamorphic Rocks • Classify rocks by arrangement of grains that make up the rock • Two types: foliated and nonfoliated

  37. Grains arranged in parallel layers Can split apart along the bands Foliated Rock

  38. Slate Shale Shale to Slate

  39. Nonfoliated Rock • Mineral grains are arranged randomly • Do not split into layers Marble

  40. Sandstone to Quartzite

  41. Uses of Metamorphic rocks • Slate and marble- most useful metamorphic rocks • Marbles- buildings and statues • Slate- flooring, roofing, chalkboards

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