Types of RocksObjective #1: 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

There are 3 Major Rock There are 3 Major Rock GroupsGroups

There are 3 Major There are 3 Major (Geologic)(Geologic) Rock GroupsRock Groups

Not the Rolling Stones, Kiss, or Van HalenNot the Rolling Stones, Kiss, or Van Halen

1. Igneous Rock1. Igneous Rock

2. Sedimentary Rock2. Sedimentary Rock

3. Metamorphic Rock3. Metamorphic Rock

Rocks are made of Rocks are made of mineralsminerals

and make up Earth’s solid crustand make up Earth’s solid crust

Identifying RocksIdentifying Rocks

Igneous pattern Metamorphic pattern Sedimentary pattern

A. A. Igneous RockIgneous Rock

--Forms when a hot, molten liquidForms when a hot, molten liquid, , below ground, calledbelow ground, called magmamagma,, 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 or crystallizes inside -Forms or crystallizes inside EarthEarth

-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 (volcanic glass)

Fine-grained-made of interlocking crystals. Ex: basalt - the most common extrusive igneous rock

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 Rock*There are *There are 33 types of sedimentary rocks. types of sedimentary rocks.

*Often times, sand, mud, pebbles, or *Often times, sand, mud, pebbles, or shells settle out in wind and water, get shells settle out in wind and water, get compacted and/or cemented together, compacted and/or cemented together, and harden into rock.and harden into rock.

Here, rocks hardened in layers called strata from a process known as… stratification.

3 Types of Sedimentary 3 Types of Sedimentary RockRock

1. 1. ClasticClastic - -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.

Rocks are made, Rocks are made, destroyed, and created destroyed, and created

again, in a process called again, in a process called the the Rock CycleRock Cycle