Transcript Metamorphic Rocks ppt

METAMORPHIC
ROCKS
c. Classify rocks by their process of formation.
d. Describe processes that change rocks and the
surface of the earth.
METAMORPHIC ROCK
 “Meta”
is ancient Greek for
change.
 “Morphosis” is ancient
Greek for form.
 Metamorphic rock then is
rock that has changed from
one form to another.
ORIGINS OF
METAMORPHIC ROCK


Metamorphic rocks are rocks in which
the structure, texture, or composition of
the rock have changed. All three types of
rock can be changed by heat, pressure,
or a combination of both.
A rock’s texture or mineral composition
can change when its surroundings
change. If the temperature of pressure of
the new environment is different from
the one in which the rock formed, the
rock will undergo metamorphism.
CONTACT
METAMORPHISM


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Contact Metamorphism when
magma moves through the crust, the
magma heats the surrounding rock
and changes it.
Some minerals in the surrounding
rock are changed into other minerals
by this increase in temperature.
The greatest change occurs where
magma comes into direct contact
with the surrounding rock.
REGIONAL
METAMORPHISM
Regional metamorphism occurs
when pressure builds up in rock
that is buried deep below other
rock formations, or when large
pieces of the Earth’s crust
collide with each other.
 The increased pressure and
temperature causes rock to
become deformed and
chemically changed.

METAMORPHISM
HOW METAMORPHIC
ROCKS FORM
 Deep
below the Earth’s
surface the intense heat
and pressure can change
rocks.
 Their appearance, texture,
crystal structure and
mineral content can change.
 Fossils will be destroyed.
ALMOST MELTED!
 Metamorphic
rocks are often
squished, smeared out, and
folded.
 Despite these uncomfortable
conditions, metamorphic
rocks do not get hot enough
to melt, or they would
become igneous rocks.
CLASSIFYING
 Classified
by the arrangement
of the grains.
 Foliated
 Non-foliated
 Usually harder and denser than
the rock they come from.
TEXTURE OF
METAMORPHIC ROCK
All
metamorphic
rock has one of two
textures.
Foliated
Metamorphic Rock
Non-foliated
Metamorphic Rock
FOLIATED METAMORPHIC
ROCK
Grains are in parallel
layers of bands.
 “Foliated” is the
Latin word for leaf.
 Describes the thin
layering found in
many metamorphic
rocks.
 These rocks will split
these bands.

SLATE
 Formed
when
shale is subjected
to pressure.
 Denser, more
compacted than
shale.
 Produces flat
plates when
broken.
SLATE TO SCHIST
If
slate is subjected to
even greater pressure
and moderate
temperatures, schist
is formed.
GRANITE TO GNEISS
Granite
becomes
gneiss when subjected
to heat and pressure.
KEY IDEA!
Heat
+ Pressure =
metamorphic rock
NON-FOLIATED ROCK
 Mineral
grains are
randomized.
 Amorphous
 Do not split into
layers
 Usually smoother
and denser than
the parent rock.
QUARTZITE
Occurs
when
sandstone is
compressed by
pressure.
Usually very hard.
MARBLE
Formed
from
metamorphosed
limestone
Much harder and
denser