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Rocks!!!

Rocks!!!. Ch. 3. What is a rock?. Any solid mass of mineral or mineral-like matter that occurs naturally as part of our planet 3 types Igneous Sedimentary Metamorphic. The rock cycle.

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Rocks!!!

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  1. Rocks!!! Ch. 3

  2. What is a rock? • Any solid mass of mineral or mineral-like matter that occurs naturally as part of our planet • 3 types • Igneous • Sedimentary • Metamorphic

  3. The rock cycle • Interactions among Earth’s water, air, land, and living things can cause rocks to change from one type to another • A continuous process

  4. Igneous Rocks • Forms when lava or magma hardens. • Lava: • Molten rock on the surface of the Earth • Magma: • Molten rock beneath Earth’s surface.

  5. Igneous Rock Formation • Igneous rocks are formed by the cooling of molten rocks and the crystallization of minerals.

  6. Types of igneous rocks • Intrusive Igneous rock: forms when magma hardens beneath Earth’s surface • Extrusive Igneous Rock: forms when lava hardens on the surface of the Earth

  7. Classifying igneous rocks • Igneous Rocks are classified based on their texture and composition.

  8. Texture classification • Texture: size, shape, and arrangement of interlocking crystals. • Course Grained: slow cooling, large crystals. • Fine Grained: rapid cooling, small interconnected mineral grains. • Glassy: looks like glass, extrusive igneous rocks. Ex. Obsidian • Porphyrite: large crystals embedded in a matrix of much smaller crystals.

  9. Composition classification • Composition: based on proportions of light to dark minerals • Basaltic Composition • Contains many dark silicates minerals and plageoclase feldspar • Rich in magnesium and iron • Ex: basalt and gabbro • Granitic Composition • Made almost entirely of light-colored silicate minerals like quartz and feldspar • 0 to 25% dark minerals • Biotite and amphibole

  10. Composition classification • Andesitic Composition • Between basltic and granitic composition • At least 25% dark minerals • Ultramafic Composition • Composed mainly of iron and magnesium rich mineral • Almost entirely dark minerals

  11. Igneous chart

  12. What is a Sedimentary rock? • Forms when existing rocks are broken down into sediment then compacted and cemented together • Processes • Cementing • Compaction

  13. How do they form? • Weathering: Any process that break rocks into sediments • Erosion : The removal of weathered rocks • Deposition: when an agent of erosion (water, wind, ice, or gravity) loses energy, it drops the sediment • Compaction: is a process that squeezes or compacts sediments together • Cementation: takes place when dissolved minerals are deposited in the tiny spaces among the sediments

  14. Classification of sedimentary rocks • Classified by the way they form • Clastic or chemical

  15. Clastic sedimentary rocks • Made of weathered bits of rocks and minerals • Grouped according to the size of the sediment.

  16. Clastic sedimentary rocks

  17. Chemical sedimentary rocks • Form when dissolved minerals precipitate from water solution • Biochemical Sedimentary Rock: made from once living organisms (like shells and skeleton remains) • Ex: limestone, chalk, conquina, rock salt, and bituminous coal

  18. What is a metamorphic rock? • Form when existing rocks are changed by heat and pressure • Metamorphism: means “change form”

  19. What causes metamorphism? • Heat: provides the energy needed to drive chemical reactions which causes existing minerals to recrystallize • Pressure: applied in all directions on a rock which causes spaces between mineral grains to close • Hydrothermal Solutions: hot, water based solutions that promote recrystallization by dissolving original minerals and then depositing new ones

  20. Classification of Metamorphic Rocks • Classified by texture and composition • Foliated • Rock with layered or banded appearance • Ex: Gneiss • Nonfoliated • No layered or banded appearance • Contains only one mineral • Ex: Marble

  21. Classification of foliated metamorphic rocks

  22. Classification of non-foliated metamorphic rocks

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