Types of Rocks

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• Types of Rocks

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3 Basic Types

• Sedimentary
• Igneous
• Metamorphic

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3 Types of Sedimentary Rocks

• Clastic
• Chemical
• Organic

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Clastic Sedimentary Rock

• Sediments form when rocks are weathered and
  eroded
• Sediments are moved by wind, glaciers and water
• Most clastic sediments are deposited in the ocean

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Clastic Sedimentary Rock

• Particle size is key to type of rock
• Gravel is gt 2 mm
• Sand is 1/16 mm to 2 mm
• Mud is lt 1/16 mm
• Clay is lt 4 um
• Silt is gt 4 um

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Sandstone
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Conglomerate
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Shale
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Chemically Precipitated Sedimentary Rock

• Ions released during chemical weathering are
  carried away in solution
• Inorganic Precipitates
• Halite
• Gypsum
• Organic precipitates
• Silica (diatoms)
• Calcium carbonate shells - CaCO3
• Dolomite - CaMg(CO3)2

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Halite
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Gypsum
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Diatomaceous Earth
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Limestone
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Dolomite
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Organic Sedimentary Rock

• Sediments or rocks consisting mostly or entirely
  from plant material
• Peat
• Coal

Bituminous
Anthracite
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Sedimentary Environments

• Lakes
• Lower courses of rivers
• Shallow ocean
• Deep ocean

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Extrusive Intrusive Igneous Rocks

• Intrusive- Magma under the surface
• Coarse-grained
• Magma cools slowly and large crystals grow over a
  long period of time
• Gabbro, diorite, granite

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Granite
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Gabbro
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Extrusive Intrusive Igneous Rocks

• Extrusive- Lava at the surface
• Fine-grained
• Lava cools very quickly, consequently crystals do
  not have time to grow and develop
• Basalt, andesite, rhyolite, obsidian

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Basalt
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Rhyolite
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Obsidian
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Explosive Volcanism

• Fragmented magma ejected explosively
• Ash plumes
• Pyroclastic flows

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Pumice
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Metamorphic Rocks

• Rocks change at the chemical level
• Grade of metamorphism
• Shearing
• Foliation

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Nature of Metamorphism

• Changes take place while a solid
• Due to heat and pressure
• Protolith original rock

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Metamorphic Rocks

• Foliated vs. Nonfoliated

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Metamorphic Rocks

• Foliated- Metamorphic rock in which minerals have
  been rearranged into visible bands.

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Schist
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Gneiss
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Slate
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Metamorphic Rocks
Nonfoliated- Metamorphic rock that does not show
bands.
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Marble
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Quartzite
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Regional vs. Contact Metamorphism

• Regional
• Contact (or thermal)

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Contact Metamorphism