1. Rocks
Chapter 4
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2. Rocks are important to to humans!
Early humans made weapons and tools with rocks.
We use rocks in many ways: buildings, statues, and concrete, to name a few .
Fossils provide clues about our planet’s history.
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3. The Rock Cycle
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4. How do we Classify Rocks?
Composition- The minerals the rock is made of.
For example, limestone is a very common sedimentary rock of biochemical origin. It is composed mostly of the mineral calcite.
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5. Rocks are also classified by texture.
Fined-grained (Siltstone)
Medium-grained (Sandstone)
Coarse-grained (Granite)
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6. Now you tell me. What are the two ways rocks are classified?
Composition
And
Texture!
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7. Igneous Rock-When magma or lava cools down enough, it solidifies and become igneous rock. There are three ways rock can melt: Temperature Pressure Compostion
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8. Composition of Igneous rocks
Felsic – light in color and are usually made of silicon, aluminum, sodium, and potassium.
Mafic - dark colored and are usually made of iron, magnesium, and calcium.
Felsic - Granite Mafic - Basalt
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9. How are Igneous rocks formed?
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10. Intrusive Igneous Rocks
When magma cools on the surface
Usually coarse-grained/ larger crystals
Plutons - intrusive formations beneath Earth’s surface
Weathering will eventually expose intrusive igneous rock.
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11. Extrusive Igneous Rock
Most volcanic rock is extrusive
Cools quickly
Cools on the surface
Lava erupts from a volcano (Lava Flow)
Small crystals
Pumice Obsidian
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12. Sedimentary Rock
Sedimentary rock forms through the process of erosion. Sediment, (rock fragments), are transported from one place to another. Eventually the sediment is deposited in layers that are compacted and cemented together.
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13. The forces that cause rock to weather into fragments are:
wind
water
ice
sunlight
gravity
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14. Composition of Sedimentary Rock
Clastic Sedimentary Rock is made from fragments of other rocks and minerals. (For example, sandstone)
Chemical Sedimentary Rock is made from solutions of minerals and water. (For example, limestone)
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15. Composition of Sedimentary Rock-continued
Fossiliferous limestone is formed from the remains of sea organisms. Shells and skeletons of tiny coral sink to the bottom of the ocean floor and over time, it cements together. This is where most limestone is formed.
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16. Sedimentary Rock Structures are characterized by stratification (or layering.) Wind and water can deposit sediments in unique patterns.
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17. Metamorphic Rock
Metamorphism is when a rock that has gone through a change from heat and pressure. This can happens with all kinds of rocks.
Metamorphism does NOT melt rock.
Metamorphism can happen by coming in contact with magma. (It cooks the rock.)
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18. Metamorphism can happen by coming in contact with magma
Metamorphism can happen by coming in contact with magma. (It cooks the rock.)
Contact Metamorphism–
Next to an igneous intrusion
See # 5 on next slide.
Regional Metamorphism—Pressure is built up when deeply buried.
See # 3 on next slide.
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20. Composition of Metamorphic Rock
As rock encounters new temperature and new pressure, the minerals in the rock will change. For example, if calcite, quartz, and hematite are combined under heat and pressure, they can turn into garnet.
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21. Textures of Metamorphic Rock
Foliated-mineral grains are aligned
Non-foliated-no alignment of minerals
Foliated Non-foliated
Slate Marble
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22. Rock Cycle Song (Sing to the tune of "Row, Row, Row Your Boat")
Sing for an extra point!
Rock Cycle Song (Sing to the tune of "Row, Row, Row Your Boat")
SEDIMENTARY rock Has been formed in layers, Often found near water sources With fossils from decayers,
Then there's IGNEOUS rock Here since Earth was born, Molten Lava, cooled and hardened That's how it is formed,
These two types of rocks Can also be transformed, With pressure, heat and chemicals METAMORPHIC they'll become.
Rock Cycle Song!
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