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Ch. 2 Rocks: Mineral Mixtures

Ch. 2 Rocks: Mineral Mixtures. Section 1: The Rock Cycle. Section 1: The Rock Cycle. rock - a naturally occurring solid mixture of one or more minerals and/or organic matter. The Value of Rock. Uses of rock: Early humans - tools, weapons For centuries - buildings, monuments, roads

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Ch. 2 Rocks: Mineral Mixtures

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  1. Ch. 2Rocks: Mineral Mixtures

  2. Section 1:The Rock Cycle

  3. Section 1: The Rock Cycle • rock - a naturally occurring solid mixture of one or more minerals and/or organic matter.

  4. The Value of Rock Uses of rock: Early humans - tools, weapons For centuries - buildings, monuments, roads Modern buildings - concrete, plaster (made from rock)

  5. Processes That Shape the Earth • Weathering - the process in which water, wind, ice, and heat break down rock into fragments (sediment).

  6. Processes That Shape the Earth • Erosion - the process by which wind, water, ice, or gravity transports soil and sediment from one location to another.

  7. Processes That Shape the Earth • Deposition - the process by which sediment moved by erosion is dropped and comes to rest.

  8. Processes That Shape the Earth • Heat and pressure can lead to the creation of each type of rock.

  9. Processes That Shape the Earth • Uplift - movement within the Earth that causes rocks inside the Earth to be moved to the Earth’s surface.

  10. The Rock Cycle

  11. The Rock Cycle • Interactive Rock Cycle Animation

  12. Rock Classification • Composition - the chemical makeup of a rock. Granite 55% feldspar 35% quartz 10% biotite mica

  13. Rock Classification • Texture - the size, shape, and positions of the grains that make up a rock. Siltstone Fine-grained Sandstone Medium-grained Conglomerate Coarse-grained

  14. Section 2: Igneous Rock

  15. Igneous Rock • Igneous rock - forms when magma cools and solidifies. • The type of igneous rock formed depends on: 1. The composition of the magma 2. The amount of time it takes the magma to cool

  16. Origins of Igneous Rock Magma can form when: 1. Rock is heated 2. Pressure is released 3. Rock changes composition

  17. Origins of Igneous Rock • When magma cools, it solidifies into igneous rock. • Magma’s freezing point is b/w 700C and 1,250C. • Magma is a complex mixture of different minerals w/different melting points.

  18. Origins of Igneous Rock • Igneous Rock Animation

  19. Felsic Rocks - Light-colored - Less dense - Rich in aluminum, potassium, silicon, sodium Mafic Rocks - Dark-colored - More dense - Rich in calcium, iron, magnesium Composition of Igneous Rock

  20. Less Time to Cool Less time for crystals to grow Smaller crystals (if any), finer texture Texture of Igneous Rock More Time to Cool • More time for crystals to grow • Larger crystals, coarser texture Basalt Gabbro

  21. Texture of Igneous Rock Fine-grained igneous rock Coarse-grained igneous rock

  22. Igneous Rock Formations • Intrusive igneous rock - forms from the cooling and solidification of magma beneath the Earth’s surface. - cools slowly - coarse-grained

  23. Igneous Rock Formations Masses of Intrusive Igneous Rocks • plutons - large, irregular shaped • batholiths - the largest of all • stocks - smaller than batholiths • dikes - sheetlike, cut across previous rock units • sills - sheetlike, cut parallel to previous rock units • volcanic neck - hardened core that’s left behind after the volcano erodes away

  24. Volcanic Neck

  25. Shiprock, New Mexico

  26. Shiprock

  27. Shiprock Dikes

  28. Igneous Rock Formations • Extrusive igneous rock - forms from the result of volcanic activity at/near the Earth’s surface. - cools quickly - fine-grained

  29. Igneous Rock Formations • Lava can flow from fissures - long cracks in the Earth’s crust.

  30. Igneous Rock Formations • A large amount of lava from a fissure can cover a large area and form a lava plateau.

  31. The Birth of an Island • Urban Legends Reference Pages: Birth of an Island

  32. Section 3: Sedimentary Rock

  33. Origins of Sedimentary Rock • Weathering breaks rock into fragments called sediment. • Sediment is moved and deposited in layers called strata. • Dissolved minerals separate from water that passes through the sediment to form a natural cement that binds the sediment into sedimentary rock.

  34. Composition of Sedimentary Rock • Clastic Sedimentary Rock - fragments of rock cemented together by minerals such as calcite or quartz - coarse-, medium-, or fine-grained textures Conglomerate Sandstone Siltstone Shale

  35. Composition of Sedimentary Rock • Chemical Sedimentary Rock - solutions form from minerals that dissolved in water passing over them - dissolved minerals eventually crystallize

  36. Composition of Sedimentary Rock • Organic Sedimentary Rock - form from the remains of organisms - ex. - coral reefs - the skeletons of coral are cemented together to form fossiliferous limestone

  37. Composition of Sedimentary Rock Mollusk shells

  38. Composition of Sedimentary Rock Coal

  39. Sedimentary Rock Structures • Stratification - the process in which sedimentary rocks are arranged in layers. • Layers differ based on kind, size, and color of sediment

  40. Sedimentary Rock Structures Ripple Marks Mud Cracks

  41. Section 4: Metamorphic Rock

  42. Metamorphic Rock metamorphism In a metamorphic rock, the structure, texture, or composition of the rock has been changed by heat and/or pressure. change shape

  43. Origins of Metamorphic Rock • Most metamorphism occurs: •at 50°C - 1,000°C+ • at depths of 2 km+ • greater depths = greater pressure allows rock to remain a solid above its melting point

  44. Origins of Metamorphic Rock • Large movements within the crust can create enough pressure to cause the mineral grains in rock to align themselves in certain directions.

  45. Origins of Metamorphic Rock • Contact metamorphism - when rock is heated enough by nearby magma to change. - occurs near igneous intrusions

  46. Origins of Metamorphic Rock • Regional metamorphism - occurs deep w/in the crust - pressure builds up or collisions occur -  pressure/temp. change the rock

  47. Composition of Metamorphic Rock • Metamorphism occurs when temp./pressure inside the Earth’s crust change. • The original minerals change into minerals that are more stable in these new conditions. calcite Heat and pressure quartz + = hematite garnet

  48. Composition of Metamorphic Rock • Index minerals form only at certain temperatures and pressures. - They’re used to estimate the temperature, depth, and pressure at which a rock undergoes metamorphism.

  49. Composition of Metamorphic Rock Ex. - a rock containing garnet formed at a greater depth and under greater heat and pressure than a rock that contains chlorite. Chlorite 400°C 4-32 km Garnet 700°C to 1,200°C 25-60 km

  50. Textures of Metamorphic Rock • Foliated - the texture of metamorphic rock in which the mineral grains are arranged in planes or bands. Shale (sedimentary) Slate

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