3 types of rocks ppt

3 types of rocks• There are 3 types of rocks found on Earth: – Igneous – Sedimentary – Metamorphic • Knowing the differences between these 3 types of rocks allows us to learn about Earth

3 types of rocks

3 types of rocks

• There are 3 types of

rocks found on Earth:

– Igneous

– Sedimentary

– Metamorphic

• Knowing the differences

between these 3 types

of rocks allows us to

learn about Earth’s past

Igneous Rocks - Formation

• Igneous Rocks are

activity, hot spots, and

melting that occurs in

the mantle.

Igneous rocks

• Igneous rocks are common along plate

boundaries or mantle hot spots

Igneous Rocks - Classification

• Igneous rocks are classified

using their texture in the

following ways:

– Glassy

– Aphanitic (no visible crystals)

– Phaneritic (visible crystals)

– Porphyritic (Some visible and

some not visible crystals)

Igneous Rocks - Texture

• Crystal size is used to

classify igneous rocks

• Crystals form as the

rock cools, and the

crystal size can tell us a

lot about its cooling

history:

– The larger the crystals,

the slower it cooled.

Igneous Rocks - Texture

• Glassy igneous rocks

have no crystal

structure, and probably

formed by very rapid

cooling (such as on the

surface of a lava, or

when a lava enters the

water.)

Igneous Rocks - Texture

• Aphanitic rocks have no

visible crystals, and

probably formed by fast

cooling above ground

Igneous Rocks - Texture

• Phaneritic rocks have

visible crystals, and

probably formed by

slow cooling below

ground

Igneous Rocks - Texture

• Porphyritic rocks have

both visible and

nonvisible crystals, and

probably formed by two

different cooling events

Igneous Rocks - Classification

• Dark igneous rocks are

formed from basaltic or

mafic magma (Mafic

because it contains a lot

of magnesium and iron)

• The magma that forms

these rocks is usually very

hot (around 1000°C) and

viscous (about the same

viscosity as ketchup.)

Igneous Rocks - Classification

• Light colored igneous

rocks are formed from

silicic (high silica content)

or felsic magmas

• The magmas that form

these rocks is usually

more cool, (lower than

850°C), and more viscous

(about the viscosity of

peanut butter.)

Igneous rocks - Formations

– Pahoehoe lava flows

– Dikes, sills, and

batholiths (plutons)

– Pillow basalts

– Volcanoes

Igneous Rocks - Examples

• The most common

types of igneous rocks

Igneous rocks charted

Igneous rocks - Story

• What do you know

about the history of the

Earth in the place where

this rock was found?

Sedimentary Rocks - Formation

• Sedimentary rocks are

• Sedimentary rocks form

in areas where water,

wind, or gravity deposit

sediments

Sedimentary rocks - formation

• Sedimentary rocks are

likely to form in areas

Sedimentary rocks - Classification

• Sedimentary rocks are

classified into two

groups:

– Clastic rocks

– Chemically formed rocks

Sedimentary rocks – Classification

• Sedimentary rocks are

Clastic if they are made

of pieces of other rocks

that have been

weathered and eroded

• Clastic rocks are

grouped based on the

size of grain that they

are made from

Sedimentary rocks - Classification

• Very small particles

Sedimentary rocks - Classification

• Sedimentary rocks that

form from chemical

processes are called

Sedimentary rocks - formations

Sedimentary rocks - Examples

• Some of the most

– Chert (including black

flint and red jasper)

Sedimentary rocks - Story

• What do you know

about the history of the

Earth in the place where

this rock was found?

Metamorphic rocks - Formation

• Metamorphic rocks are

formed by heat and

pressure changing one

type of rock into

another type of rock

Metamorphic rocks - Formation

• Lava intrusions can

provide heat that

Metamorphic rocks - Formation

• Rocks that

metamorphose because

of increasing heat and

pressure found at plate

subduction zones and in

deep mountain roots

form large areas of

metamorphic rock

through regional

metamorphosis.

Metamorphic rocks - Classification

• Metamorphic rocks are

classified into 2 major

groups:

– Foliated

– Nonfoliated

Metamorphic rocks - Classification

• Foliated rocks form when

differential pressure causes

minerals to form in layers

• These rocks will have

stripes or planes that they

will break easily along

• These “stripes” don’t

usually line up with the

original bedding planes in

sedimentary rocks

Metamorphic rocks

• Nonfoliated

metamorphic rocks

formed in areas where

the pressure from all

sides was equal, so

there is no “linear”

quality to the rocks

Metamorphic rocks - Formations

– Alternating dark and

light layers (gneissic

foliation)

Metamorphic rocks - Examples

• Some common types of

Metamorphic rocks - Charted

Metamorphic rocks - story

• What do you know

about the history of the

Earth in the place where

this rock was found?