igneous rocks
Post on 30-Dec-2015
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Igneous rock begins as magma
What is the origin of Igneous Rock?
http://www.webquest.hawaii.edu/kahihi/sciencedictionary/images/magma_flow_up.gif
There are three ways magma can form:
1. when rock is heated,
2. when pressure is released,
3. when rock changes composition.
What are the ways that magma can form?
The longer it takes for the magma or lava to cool, the more time mineral crystals have to grow.
The more time the crystals have to grow, the larger the crystals.
The larger the crystals are the coarser the texture of the resulting igneous rock is.
What happens
to magma when it cools at different
rates?
The less time magma takes to cool, the less time crystals have to grow. Therefore, the rock that is formed will be fine grained.
What happens
to magma when it cools at different
rates?
Fine-grained igneous rock contains very small crystals, or if the cooling is very rapid, it contains no crystals.
What happens
to magma when it cools at different
rates?
What is Intrusive Igneous Rock?
Magma that intrudes, or pushes, into surrounding rock below the Earth’s surface and cools.
What is Intrusive Igneous Rock?
Usually has a coarse-grained texture because it is well insulated by surrounding rock and cools very slowly. The minerals that form are large, visible crystals.
What are the different
masses of intrusive
igneous rock named and
why?
Masses of intrusive igneous rock are named for their size and shape
PlutonsBatholithsStocks Dikes
Plutons are large, irregular-shaped intrusive bodies.
The largest of all igneous intrusions are batholiths.
Stocks are intrusive bodies that are exposed over smaller areas than batholiths.
Dikes sheetlike intrusions that cut across previous rock units.
Sills are sheetlike intrusions that are oriented parallel to previous rock units.
Plutons
Batholiths
Stocks
Dikes
Sills
Where would I find
Extrusive Igneous Rock?
Magma that erupts, or extrudes, onto the Earth’s surface. Extrusive rock is common around volcanoes.
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