http://www.videojug.com/film/geology-metamorphic-rocks
http://www.youtube.com/watch?v=kRUwchlza88
Metamorphic core of the Himalayan Mountains
Vocabulary


METAMORPHISM
 The process of a
rock changing by
heat or pressure—
or both.

FOLIATION
 Minerals
arranged in flat
or wavy parallel
bands
RECRYSTALLIZATION
 Heat and pressure break
the bonds that join
atoms in minerals. Then
the atoms join differently,
making new minerals.
Heat and Pressure
Changes Rocks
• Pressure
causes minerals to
flatten out in one direction.
• Heat and pressure break
bonds between atoms, and
recrystallization occurs.
• The higher the temperature
and pressure, the greater the
changes.
How Rocks Change…
1. Sedimentary rock, like shale, can
be buried when pushed into the crust.
shale
Increasing Heat & Pressure
2. Shale changes to slate as pressure
causes the minerals to line up in layers.
slate
3. Slate changes to phyllite deeper in
the crust with higher heat/pressure.
phyllite
4. With even more heat and pressure,
phyllite changes into schist and new
minerals are formed.
5. Deep within the crust, schist
changes to gneiss. Recrystallization
separates light and dark minerals.
schist
gneiss
Metamorphic rocks form as existing rocks go
through metamorphism –heat and pressure
Metamorphic Changes
Over Large Areas
• Change
occurs over large areas when
BOTH temperature and pressure forces
are high.
• Mountain ranges can be made.
Metamorphic Changes
Over Small Areas
•Change occurs over small areas with
high temperature OR high pressure.
•Magma can push rocks into layers or
bake surrounding rocks, causing
earthquakes.
Foliated & Nonfoliated Rocks
• Foliation develops when rocks are under
pressure.
• Foliation is common in rocks that have
changed over large areas.
• If a rock is made of mainly one mineral, it is
nonfoliated. There are no minerals to
separate and line up in layers. Marble and
quartzite are examples of this.
Rocks in the World Around Us