3 Major Groups of Rocks · Igneous rock Intrusive rock Magma Lava Small Crystals Extrusive Rock Large Crystals Inside Earth At or near surface Coarse-grained Fine Grained Cools fast

3 Major Groups of Rocks: Igneous

Sedimentary

Metamorphic

These terms refer to how the

rocks in each group formed.

3 Types of Rock

Igneous Rocks

From the Latin word igni (fire)

form from the cooling of molten rock (lava and magma).

Igneous rock

Intrusive rock

Magma

Lava

Extrusive RockSmall Crystals

Large Crystals

Inside Earth

At or near surface

Fine GrainedCoarse-grained

Cools fast

Cools slowly

How do

Igneous

rocks Form?

from the cooling

of molten rock

(lava and magma

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• Explosive eruption, Kilauea 1924Mt. St. Helens, 1980

Are lava and magma the same?

LAVA is molten material found on the surface of the

earth.

MAGMA is molten material found beneath the surface

of the earth.

What is Lava?

What is Magma?

molten material found on the surface of the earth.

molten material found beneath the surface of the earth.

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Classified by Formation:

Extrusive Rock is formed from lava erupted onto Earth’s surface.

Exits the Earth

(Basalt)

Classified by Formation:

Intrusive Rock is formed when magma hardens beneath

Earth’s surface.

Inside the Earth

(Granite)

How does Extrusive Rock form?

How does Intrusive Rock form?

When lava erupts onto Earth’s surface

When magma hardens beneath Earth’s surface

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How was Mount Rushmore made?

https://www.youtube.com/watch?v=Bvj2URpgRc8

Intrusive Igneous Rock

• Stone Mountain, Georgia

Classified by Texture:

Fast Cooling Lava (Extrusive)

Fine-Grained, small crystals, smooth

Slow Cooling Magma (Intrusive)

Coarse-Grained, large crystals, rough

How fast do

these rocks

cool?

Extrusive: Fast cooling lava (Fine-Grained or glassy texture.)

Intrusive: Slow cooling Magma. (Ex. Coarse-Grained, large crystals. Smooth & rough.)

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An intrusive igneous rock would have what type of texture? Why?

Coarse-Grained, large crystals. Smooth & rough.

It is hotter in the earth than on the outside of the earth so it takes longer for magma

to cool down.

Igneous rock

Intrusive rock

Magma

Lava

Extrusive RockSmall Crystals

Large Crystals

Inside Earth

At or near surface

Fine GrainedCoarse-grained

Cools fast

Cools slowly

• Granite has a coarse-grained texture

An extrusive igneous rock would have what type of texture? Why?

Fine-Grained or glassy texture

It is cooler on the surface of the Earth so the rocks can cool faster.

• Rhyolite has a fine-grained texture

• Obsidian has a glassy texture

Classified by Mineral Composition:

Mafic describes dark colored rocks because of low silica (basalt,

peridotite)

Felsic describes light colored rocks because of high silica (granite, rhyolite

)

Dark vs.

Light

Minerals?

Mafic describes darkcolored rocks

Felsic describes lightcolored rocks

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Mineral Composition Igneous Rocks

Granite is made of:

Feldspar, Mica, Quartz, Horneblende (dark)

Rhyolite is made of:

Feldspar, Mica, Quartz, Horneblende

Obsidian is made of:

Quartz, Iron, Magnesium

How do you use igneous rocks?

Tools Gravel

Buildings Cleaning

Streets Polishing

Bridges Gardening

Formation

Sedimentary Rock

Sedimentary rocks are classified based on formation

Sedimentary rocks form at or near the surface

Formation

Where do

Sedimentary

rocks form?

form at or near the surface of the earth

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Breaking down of material by wind, water, ice, sunlight, & gravity

Weathering

What is weathering?

It is the breaking down of material by wind, water, ice, sunlight, & gravity

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Movement of sediment

Erosion

What is

erosion?

The movement of sediment

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Rock & mineral fragments

Sediment

Sediment is dropped into a new place

Sediment deposited in layers- lithification

Deposition

Layers of sediment build up and are pressed down

Pushed together

Compaction

What is

compaction?Layers of

sediment build up and are pushed together

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Dissolved minerals such as quartz or calcite act as a natural glue cementing sediment together

Cementation

Layers found in sedimentary rock

Strata

What is cementation?

What are Strata?

Dissolved minerals act as a natural glue cementing sediment together

Layers found in sedimentary rocks

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Rock & mineral fragments compacted & cemented together

Classified by grain size

Ex. Sandstone, breccia, conglomerate, shale

Clastic

Formed from solutions of dissolved minerals & water

Minerals crystallize out of solution

Ex. Halite, limestone, gypsum

Chemical

Contain remains, fossils of ocean animals

Ex. Fossiliferous limestone

Ex. Coal- forms underground from plant material buried under sediment & changed to coal over millions of years

Organic

What are the three types of sedimentary rock?

Clastic: (Rock & mineral fragments compacted & cemented together)

Chemical: (solutions of dissolved minerals & water)

Organic: (Contain remains, fossils of ocean animals)

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Sedimentary Rocks

Breccia Sandstone Limestone Coal

(clastic) (clastic) (organic) (organic)

FYI: In 1631, the Emperor of India was grief stricken when his wife died. He loved her so much that he

created the Taj Mahal as a place where she would be entombed. His body was also placed there after

he died. The Taj Mahal was built of white marble inlaid with semi-precious stones.

.

Metamorphic

Rocks

Metamorphic Rock

Formed when tremendous

pressure and heat beneath

Earth’s surface changes

one type of rock into

another type of rock.

2 Kinds of Metamorphic

Rock

1) Foliated

2) Nonfoliated

FoliatedEx – Slate, schist, and gneiss

Nonfoliated

Ex – Marble and Quartzite

ite

Granite

(intrusive

igneous)

Gneiss (foliated

metamorphic)

Shale (clastic

sedimentary)

becomes Slate

(foliated

metamorphic)

Sandstone

(clastic

sedimentary)

Quartzite

(nonfoliated

metamorphic)

Limestone (organic sedimentary)

Marble (nonfoliatedmetamorphic)

Limestone Marble

Draw this box in your IAN. Use your notes

and write the definition

Definition Characteristics

Examples Non-examplesMetamorphic