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Metamorphic Rocks

Metamorphic Rocks. Herricks High School Earth Science. Metamorphism. The changes that occur in solid rock due to great temperature, great pressure, and chemical activity. Three Factors of Change. Heat Pressure Chemical Activity. Metamorphism.

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Metamorphic Rocks

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  1. Metamorphic Rocks Herricks High School Earth Science

  2. Metamorphism • The changes that occur in solid rock due to great temperature, great pressure, and chemical activity.

  3. Three Factors of Change • Heat • Pressure • Chemical Activity

  4. Metamorphism • Parent Rock- the preexisting rock from which a metamorphic rock forms Parent Rock -------------- Metamorphic

  5. Types of Metamorphism • Regional Metamorphism: occurs over large areas and is associated with mountain building • Deeply buried igneous and sedimentary rocks are squeezed by the weight of rock layers above • Examples: Slate, Phyllite, Schist, Gneiss

  6. Regional Metamorphism

  7. Contact Metamorphism • Contact Metamorphism: occurs when molten rock comes into contact with surrounding rocks

  8. How do metamorphic rocks change? 1. Crystalline Texture: Recrystallization • Under heat and pressure the size, shape, and spacing of grains change. • Rock may partially melt and fuse together forming larger crystals or pressure may break grains into smaller pieces, destroying the original texture of the rock

  9. How do metamorphic rocks change? (con’t) 2. Increased Density: • Pressure from deep burial closes pore spaces in sedimentary rocks and openings in igneous • Its mass is forced into a smaller volume, and its density increases.

  10. Visual Characteristics of Metamorphic Rocks • Foliation: results when mineral grains recrystallize or are flattened under pressure • A rock is said to be foliated when its crystals are arranged in layers or bands along which the rock breaks easily. Example: foliation of gneiss

  11. Visual Characteristics (con’t) • Banding: occurs when minerals of different densities recrystallize under pressure and separate into layers • Like oil and water • Alternate light and dark (light being less dense than dark)

  12. Banding gneiss

  13. Visual Characteristics (con’t) • Distortion of Layers: When layers of rock become metamorphosed, twisting and contorting could occur. • These distortions are commonly seen in large-scale outcrops.

  14. Distortion

  15. Name That Rock! Location: Roman Forum, Roma, Italy 7/29/2011

  16. Erosion Transportation Weathering Deposition Igneous rock Granite, pumice, basalt Sedimentary rock Sandstone, limestone Heat, pressure Cooling Heat, pressure, stress Magma (molten rock) Melting Metamorphic rock Slate, marble, gneiss, quartzite Fig. 15-8, p. 343

  17. The Rock Cycle: The Story of “Herbie”

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