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