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Rocks

Rocks. ROCKS. Chapter 6. Rocks. Naturally occurring solid material made of one or more minerals Grouped into 3 main types, based on the way it was formed. IGNEOUS ROCKS. #1. IGNEOUS ROCKS. Formed from magma that cools and hardens “Fire Formed”. Intrusive rocks:

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Rocks

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  1. Rocks ROCKS Chapter 6

  2. Rocks • Naturally occurring solid material made of one or more minerals • Grouped into 3 main types, based on the way it was formed

  3. IGNEOUS ROCKS #1

  4. IGNEOUS ROCKS • Formed from magma that cools and hardens • “Fire Formed”

  5. Intrusive rocks: formed deep within Earth Cools slowly, large crystals Coarse grained Extrusive rocks: formed from lava at Earth’s surface Cools quickly, small crystals fine grained IGNEOUS ROCKS: 2 types

  6. IGNEOUS ROCKS: texture • Size of crystal grains and chemical composition are used to classify igneous rocks • Texture depends on time it takes a rock to harden (cooling rate)

  7. IGNEOUS ROCKS: porphyry(POR-fuh-ree) • Igneous rock with a mixture of large and small crystals

  8. Felsic: Light-colored Thick and slow flowing Rich in silica Mafic: Dark-colored Very fluid Rich in iron Two types of magma

  9. Scoria

  10. Intrusions (pluton) –underground rock masses Extrusions – surface rock masses Igneous Rock Structures

  11. INTRUSIONS • Batholiths • largest igneous intrusions • Form when huge bodies of magma cool underground • Cover 1000 km

  12. Batholith

  13. INTRUSIONS • Sill • Sheet of hardened magma that forms between and parallel to layers of rock • Dike • Sheets of igneous rocks that cut across the rock layer

  14. Dike

  15. Sill

  16. EXTRUSIONS • Volcanic neck: • The plug of hardened magma left in the vent from which lava flowed

  17. SEDIMENTARY ROCKS #2

  18. Sedimentary Rocks • 75% of Earth’s surface is sedimentary rock!

  19. How Sedimentary Rocks are made: • Mud, sand, gravel and shells are sediments that make up rocks • Sediments are moved by wind and water • Compaction: Pressure placed in sediment layers cause them to change to rocks • Cementation: sediments are joined together (cemented) by minerals dissolved in water • This process results in the formation of layers called strata.

  20. The major characteristics of all sedimentary rocks is that they form layers!

  21. "For your information, there's a lot more to ogres than people think... Ogres are like sedimentary rocks! …Sedimentary rocks have layers... Ogres have layers! ...We both have layers."

  22. Sedimentary rocks usually form in water • Ripple marks and mud cracks

  23. Fossils often preserved in sedimentary rocks

  24. Sedimentary Rocks: Classified by • Composition • Texture • Grain size

  25. 3Types of Sedimentary Rocks: • Clastic • Organic • Chemical

  26. 1. Clastic Rocks • Formed by broken pieces or fragments of rock • Classified according to size and shape of fragments

  27. Clastic Rocks Conglomerates: • Made of rounded pebbles and other rocks of different sizes and cemented together by clay, mud ,or sand • Formed when rivers deposit large pieces of rock • Pieces of rock rounded by water before deposited

  28. Clastic Rocks Breccia: • Similar to conglomerates, but fragments are sharp and angular • Not carried far enough by water to round the edges

  29. Clastic Rocks Sandstone: • Made of small, sand-sized grains • Very common • Resistant to wear and decay • Used to make buildings

  30. Clastic Rocks Mudrock: • Formed from small particles of clay • Example: shale

  31. shale

  32. 2. Organic Rock • Formed directly or indirectly from material that used to be living

  33. Organic Rock Fossilized Limestone: • Shells from dead animals (containing calcium carbonate) that sink to bottom of ocean floor

  34. Organic Rock Chalk: Composed of animals and calcium carbonate that have been pressed together

  35. Organic Rock Coal: • Rock formed from plants that lived millions of years ago

  36. 3. Chemical Rock • Formed by chemical means that do not involve any living organisms • Can occur through evaporation or chemical action

  37. Chemical Rock Limestone: • Formed directly from ocean water instead of organisms

  38. Chemical Rock Rock salt: • Natural form of common table salt • Ex: Halite

  39. METAMORPHIC ROCKS #3

  40. Metamorphic Rocks Metamorphism: • Changing of one type of “parent” rock in to another due to - • Tremendous heat • Great pressure • Chemical reactions ( a change in composition of minerals)

  41. Metamorphic Rocks Types of Metamorphism: • Contact Metamorphism • Occurs when rocks are heated by contact with magma or lava • Covers a small area • Regional Metamorphism • Occurs when rocks are buried deep beneath Earth’s surface and changed by increase in temperature and pressure • Covers a large area

  42. Types of Metamorphic Rock: • Foliated Texture: Mineral crystals arranged in parallel layers or bands (flatten under pressure) Slate  Schist  Gneiss (from clay or shale) (from granite, basalt, or slate) (from granite)

  43. Foliated Texture: slate

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