3 Major Rock Groups

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3 Major Rock Groups
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3 Major (Geologic) Rock Groups

• Igneous Rock
• Sedimentary Rock
• Metamorphic Rock

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Identifying Rocks
Metamorphic pattern
Sedimentary pattern
Igneous pattern
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A. Igneous Rock

• -Forms when hot, liquid, rock crystallizes
  (cools and solidifies).
• Magma forms 3 ways
• Rock is heated
• Pressure released
• Change composition

Holt Online Visual Comparing Int. Ext Igneous
Rocks
Basalt lava (glowing rock) oozes over basalt lava
flow
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• Intrusive Igneous Rock
• -Forms inside Earth
• -slow cooling

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• b. Extrusive Igneous Rock
• -Forms on surface (exterior) of Earth
• -Fast cooling

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a. Composition of Igneous Rock

• Felsic Rock
• -Light colored
• -made of aluminum, potassium, silicon, and
  sodium.
• Mafic Rock
• -Dark colored
• -Made of calcium, iron, and magnesium.

Fine-grained
Course-grained
Course-grained
Fine-grained
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b. Texture of Igneous Rock

• -Slow cooling forms large crystals.
  (Coarse-grained Texture)
• -Fast cooling forms small crystals.
  (Fine-grained Texture)

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• -Rate of cooling influences crystal size.
• Fast cooling small crystals
• Slow cooling large crystals

Show Holt Visual Igneous Rock Texture
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Rock ID practice Use the rock key to identify
the various rocks on your table
Igneous Rocks

• Classified according to two qualities or traits
• composition texture.
• Glassy- shiny and looks
• like glass, not organized
• into crystals.
• Ex obsidian

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• Fine-grained-made of interlocking crystals.
• Ex basalt

BASALT
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More Igneous Rocks
Course Grained Texture- Granite
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More Igneous Rocks

• Porous- no crystals, cools rapidly, looks like a
  sponge.
• Ex pumice

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More Igneous Rocks
Diffferent size crystals locked together
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More Igneous Rocks
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Igneous Rock Pop Quiz!Answer these in your NB

• What size crystal forms from extrusive rock?
• What is one way magma forms?
• Generally speaking what color are felsic rocks?
• 4. Quality (trait) of a rock based on the size,
  
• shape, and arrangement of grains is
• referred to as its (See
  slide 12)
• 5. What are the 2 characteristics that
  geologists
• study to classify identify rocks?

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Sedimentary Rock

• Strata layers of rock.
• Stratification The process in which sedimentary
  rocks are arranged in layers.

Holt Visual Sedimentary Rock Cycle
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3 Types of Sedimentary Rock

• 1. Clastic forms when rock or mineral fragments
  are cemented together.

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• 2. Chemical forms when minerals crystallize out
  of solution, such as sea water, to become rock.

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• 3. Organic forms from the remains of once-living
  plants and animals.
• Ex Limestone
• Coal
• Chalk

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Sedimentary Pop QuizMake 5 questions of your own
in your NBPut the answers on the back side of
your quiz page

• 1.
• 2.
• 3.
• 4.
• 5.

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Metamorphic Rock

• -Rocks that have undergone a change in texture,
  structure, or composition.
• -Changes in heat and pressure cause rocks to
  change from one form to another.

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Origins of Metamorphic Rock
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• Contact Metamorphism
• Rock undergoes metamorphism when it comes in
  contact with magma or is heated by nearby magma.

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• Regional Metamorphism
• -Pressure builds up in rock that is buried deep
  below rock formations or when large pieces of
  rock collide.

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Textures of Metamorphic Rock
Foliated the texture of metamorphic
rock in which the mineral grains
are arranged in planes or bands.
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• Nonfoliated
• -The texture of metamorphic rock in which the
  mineral grains are not arranged in planes or
  bands.

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Metamorphic Pop QuizMake 5 questions of your own
in your NBPut the answers on the back side of
your quiz page

• 1.
• 2.
• 3.
• 4.
• 5.