Download Metamorphic Rocks

 “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.
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 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 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.
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.
 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.
 Classified
by the arrangement
of the grains.
 Foliated
 Non-foliated
 Usually harder and denser than
the rock they come from.
All
metamorphic rock
has one of two textures.
Foliated Metamorphic
Rock
Non-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.
 Formed
when
shale is subjected
to pressure.
 Denser, more
compacted than
shale.
 Produces flat
plates when
broken.
If
slate is subjected to
even greater pressure
and moderate
temperatures, schist is
formed.
Granite
becomes gneiss
when subjected to heat
and pressure.
Heat
+ Pressure =
metamorphic rock
 Mineral
grains are
randomized.
 Amorphous
 Do not split into
layers
 Usually smoother
and denser than
the parent rock.
Occurs
when sandstone
is compressed by
pressure.
Usually very hard.
Formed
from
metamorphosed
limestone
Much harder and
denser