Transcript Rocks - Think Geography

What things are rocks
used for?
Rocks
What are rocks?
• Rock is a compact mass of mineral matter
Types of Rocks
Igneous Rocks
Metamorphic Rocks
Sedimentary Rocks
Igneous rocks
Igneous Rocks
What are They?
Fire Rocks
 Formed underground by trapped, cooled
magma
 Formed above ground when volcanoes erupt
and magma cools
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Types of Igneous Rocks
Granite
Scoria
Pumice
Obsidian
Igneous Rocks
• These are rocks that are formed by the
cooling and solidification of molten rock
(magma) from beneath the earth’s crust.
They are normally crystalline. Lava
forms igneous rock. Granite and basalt
are the main examples.
Types of Sedimentary Rocks
Sandstone
Limestone
Gypsum
Conglomerate
Shale
Sedimentary Rocks
How They are Made
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Wind and water break down the earth
Bits of earth settle in lakes and rivers
Layers are formed and build up
Pressure and time turn the layers to rock
Sedimentary rock
• This is a group of rocks that is formed from
sediments – they
• Have accumulated overlong periods of time, and
usually under water
• Have a layered structure, and are described as
being stratified
• Often contain fossils
• Sandstone, limestone, chalk and coal are all
examples
Metamorphic Rocks
What are They?
Rocks that have changed
 They were once igneous or sedimentary
 Pressure and heat changed the rocks
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Types of Metamorphic Rocks
Schist
Gneiss
Metamorphic rock
• These are a type of rock which has been altered
from an earlier one by heat and/or pressure.
• For example – marble is a metamorphic rock
which was once limestone, a sedimentary rock.
• Metamorphic rocks are tough and resistant to
erosion and are often used as building materials eg
Slate
Rocks
What is weathering?
What is Erosion?
Weathering is . . . Erosion is . . .
• Weathering is the breakdown of rocks due
to the weather
• Erosion is the breakdown of rock due to
their contact with water, ice, heat or
anything which rubs against the rock