Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
A Closer Look At Rocks
Do you remember the names of the 3 rock families?
That’s Right!
Igneous
Sedimentary
Metamorphic
Let’s Take a Closer Look at Igneous Rocks!
These rocks are formed from either magma or lava
Intrusive igneous rock are formed inside the Earth from magma
– Usually take a long time to cool and have large crystals
Extrusive igneous rock is formed on the Earth’s surface from lava
– Take a shorter time to cool and have small crystals
Igneous rocks are usually the hardest type of rock and last longer than any other type of rock
Sedimentary Rocks
These rocks are formed from sediment
– Rock particles, decaying animals, plants and minerals
– Layers can be made on land or in water
Particles are moved around by water, wind and ice
Forming Loose Sediment into Rock
Rock particles get pressed together forming layers that make up sedimentary rock
Some small particles may be formed into rock by pressure alone examples silt and clay
In some sedimentary rocks the particles are held together by minerals that have crystallized acting as a cement
Metamorphic Rock
Heat and Pressure Change Rocks
When a rock changes by heat and or pressure it undergoes metamorphism
– The original igneous or sedimentary rock is called the parent rock
– It changes into a metamorphic rock
A metamorphic rock can also be a parent rock
– It changes into another metamorphic rock
Metamorphism
Pressure causes the minerals to flatten out
It remains as a solid
Rocks DO NOT MELT when they undergo metamorphism
Recrystallization
Heat and pressure break bonds. Then the atoms rejoin in a new way and form new bonds
Crystals can become larger as more atoms join the crystal structure
Atoms can combine in a different way and new minerals can be formed.
Metamorphic Rocks Develop Bands of Minerals
Foliation – Arrangement of minerals in flat or wavy parallel
bands
Foliated rocks – Foliation occurs when a rock is under pressure
– This develops when minerals flatten out
Non-foliated rocks – May not display foliation because it is made up of
one mineral
– Example – marble
– It may not have been subjected to high pressure