Types of Rocks Thursday 9/30 Objective: Describe and classify igneous rocks Agenda: 1.Journal entry: What does the word igneous mean? How do igneous rocks.

Types of Rocks Thursday 9/30Objective: Describe and classify igneous rocks

Agenda:1.Journal entry: What does the word igneous mean? How do igneous rocks form?2. Review webquest and directed reading3. Notes on igneous rocks4. Identify and describe samples

3 Major Rock Groups3 Major Rock Groups

3 Major (Geologic) Rock 3 Major (Geologic) Rock GroupsGroupsIgneous RockIgneous Rock

Sedimentary RockSedimentary Rock

Metamorphic RockMetamorphic Rock

Identifying RocksIdentifying Rocks

Igneous pattern Metamorphic pattern Sedimentary pattern

A. A. Igneous RockIgneous Rock

--Forms when Forms when hot, liquid, magmahot, liquid, magma crystallizes (cools and solidifies).crystallizes (cools and solidifies).

Magma forms 3 ways:Magma forms 3 ways:1.1. Rock is heatedRock is heated2.2. Pressure releasedPressure released3.3. Change compositionChange composition

Basalt lava (glowing rock) oozes over basalt lava flow Holt

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a.a. Intrusive Igneous RockIntrusive Igneous Rock

-Forms inside Earth-Forms inside Earth

-slow cooling-slow cooling

b. b. Extrusive Igneous RockExtrusive Igneous Rock

-Forms on surface (exterior) of -Forms on surface (exterior) of EarthEarth

-Fast cooling-Fast cooling

Felsic RockFelsic Rock

-Light colored -Light colored

-made of -made of aluminum, aluminum, potassium, silicon, potassium, silicon, and sodium.and sodium.

Mafic RockMafic Rock

-Dark colored-Dark colored

-Made of calcium, -Made of calcium, iron, and iron, and magnesium.magnesium.

Course-grained Fine-grained

Course-grained Fine-grained

a. Composition of Igneous Rock

b. b. Texture of Igneous Texture of Igneous RockRock

--Slow Slow cooling cooling forms large forms large crystals. crystals. (Coarse-(Coarse-grained Texture)grained Texture)

--FastFast cooling cooling forms small forms small crystals. crystals. (Fine-(Fine-grained Texture)grained Texture)

-Rate of cooling -Rate of cooling influences crystal influences crystal size.size.

Fast cooling = small Fast cooling = small crystalscrystals

Slow cooling = large Slow cooling = large crystalscrystals

Show Holt Visual: Igneous Rock Texture

Pop Quiz!Pop Quiz!1.1. What size crystal forms from extrusive rock?What size crystal forms from extrusive rock?

2.2. What is one way magma forms?What is one way magma forms?

3.3. Generally speaking what color are felsic Generally speaking what color are felsic rocks?rocks?

4. Quality of rock based on the size, 4. Quality of rock based on the size,

shape, and arrangement of grains is shape, and arrangement of grains is

referred to as…referred to as…

5. What are the 2 characteristics that geologist 5. What are the 2 characteristics that geologist

study to identify rock:?study to identify rock:?

Rock ID practiceUse the rock key to identify the various rocks on your table:

Igneous Rocks Classified according to composition & texture

Glassy- shiny and look like glass, not organized into crystals.

Ex: obsidian

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

BASALT

More Igneous Rocks…

Course Grained Texture- Granite

More Igneous Rocks…Porous- no crystals, cools rapidly, looks

like a sponge. Ex: pumice

Diffferent size crystals locked together

More Igneous Rocks…

More Igneous Rocks…

Sedimentary RockSedimentary RockStrataStrata layers of rock. layers of rock.

StratificationStratification The process in which The process in which sedimentary rocks are arranged in layers.sedimentary rocks are arranged in layers.

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3 Types of Sedimentary 3 Types of Sedimentary RockRock

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

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

3. 3. OrganicOrganic forms from the remains of once- forms from the remains of once-living plants and animals.living plants and animals.

Ex: LimestoneEx: Limestone CoalCoal

ChalkChalk

Metamorphic RockMetamorphic Rock

-Rocks that have undergone a change in -Rocks that have undergone a change in texture, structure, or composition.texture, structure, or composition.

-Changes in heat and pressure cause rocks -Changes in heat and pressure cause rocks to change from one form to another.to change from one form to another.

Origins of Metamorphic Origins of Metamorphic RockRock

Contact Contact MetamorphismMetamorphism Rock Rock

undergoes undergoes metamorphism metamorphism when it comes when it comes in contact with in contact with magma or is magma or is heated by heated by nearby magma.nearby magma.

Regional Regional MetamorphismMetamorphism

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

Textures of Metamorphic RockTextures of Metamorphic Rock

Foliated the texture of metamorphic rock in which the mineral grains are arranged in planes or bands.

NonfoliatedNonfoliated

-The texture of -The texture of metamorphic rock metamorphic rock in which the in which the mineral grains are mineral grains are notnot arranged in arranged in planes or bands.planes or bands.