Transcript Metamorphic rocks

Unit 2: Rocks & Minerals
Metamorphic Rocks
What does metamorphism mean?
• Metamorphism means to change form.
• Metamorphic rocks are igneous,
sedimentary, and other metamorphic rocks
that have been changed in form (usually
deep within the Earth).
What causes a rock to undergo
a change in structure?
• Metamorphism of rocks is
a result of high
temperature and pressure
(usually deep within the
Earth). The extreme
temperature and pressure
conditions cause the atoms
in existing minerals to
rearrange (or change
form).
What are the two types of
metamorphism?
Contact Metamorphism
occurs when molten
magma (or lava)
comes in contact with
other rocks and
changes them. The
primary agent of
contact metamorphism
is HEAT.
Regional metamorphism
Regional
metamorphism is the
result of exposure to
extreme HEAT and
PRESSURE deep
within the Earth.
More on Regional
Metamorphism…
• Regional metamorphism
occurs over large areas,
and is generally associated
with mountain building.
The extreme pressures
associated with the
collisions of tectonic
plates (mountain building)
can lead to the
metamorphism of rock
material.
What changes are observed in rocks
due to metamorphic processes?
• Metamorphism is the
result of
recrystalization of
unmelted minerals
under high
temperature and
pressure.
Metamorphic rocks become harder and more
dense than their parent rocks.
High Grade = Most Dense
Original layers can become bent or
distorted.
Banding and foliation are also
products of metamorphic processes.
On what basis are metamorphic
rocks classified?
Foliated metamorphic
rocks contain
alignment of
minerals, flaky layers
or light and dark
bands.
• Foliated
metamorphic rocks
are classified by the
type of foliation they
exhibit.
Nonfoliated
metamorphic rocks
display no foliation
(layering or mineral
alignment).
• Nonfoliated
metamorphic rocks
are classified by
composition.
What is foliation?
• Foliation is an alignment
of minerals, or the
separation of minerals into
flaky layers or light and
dark bands. Thick
banding indicates a high
degree of metamorphism.
(High degree means more
change).
GNEISS
Superhero Rocks
• Sandstone
• Quartzite
Superhero Rocks
• Limestone
• Marble
Superhero Rocks
• Conglomerate
• Metaconglomerate
Reference Table
• Metamorphic Rock Scheme
• Animation
Third Method
• There is a very rare 3rd method to form a
Metamorphic Rock.
NORRISIFICATION
• Chuck Norris can
Morph a Rock!!
Chemical Method
• Chemicals can sometimes cause rocks to
change form.