3. What are Rocks?
Rocks are aggregates of 2 or
more minerals.
Petrology is the study of
rocks.
There are three
classifications of rocks:
igneous, sedimentary, and
metamorphic.
4. Igneous Rocks
Granite is an igneous rock
• Igneous rocks are formed when molten rock
(magma) cools and solidifies, with or without
crystallization, either below the surface as coarse-
grained, intrusive (plutonic) rocks or on the surface
as fine- grained, extrusive (volcanic) rocks.
5. Sedimentary Rock
Sedimentary rock is formed in three main ways:
Limestone and shale are both types of
sedimentary rock
1. by the deposition of the
weathered remains of other
rocks (known as clastic
sedimentary rocks)
2. by the deposition of the
results of biogenic activity
(organic)
3. by precipitation from
solution (evaporites)
6. Metamorphic Rock
Metamorphic rock is the result of the transformation of
a pre-existing rock type.
The pre-existing rock type is called the protolith.
Pressure and heat physically and chemically change the
protolith.
Metamorphic means "change in form“.
Slate is a type of
metamorphic rock
7. Finally, The Rock Cycle!
• The Rock Cycle
refers to the
constant sequence
of one type of rock
turning into
another.
Click Here for an Animation that Further
Explains the Rock Cycle
Magma
Sediment
Sedimentary Igneous
Metamorphic
8. What Do You Think?
• Now that you have seen the
animation, what do you think energy
has to do with the progression of the
Rock Cycle?
• What are the keys to the change in
the rocks?
• Can rocks shortcut the cycle? Does
igneous always have to form
sediment or can it go straight back to
being magma?
