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Metamorphic Rocks
Pages 141-144
Formed by
 Heat
 Pressure
 Hot

fluids
Caused by
 Plate
tectonics
 Igneous
intrusion
 Deeper burial
Change occurs by
 Recrystallization
 Often
lose H2O or CO2
 Mechanical
 No
deformation
minerals are melted
Two types we will mention
 Regional
 Contact
or Barrovian
Regional Metamorphism
 Occurs
over lg areas
-state size
 Cause—
plate tectonics
Contact Metamorphism
 Rocks
that are in
contact with hot
magma or lava
often become
metamorphosed.

The metamorphic
rock that develops
depends upon the
parent rock


What is formed from
limestone?
What is formed from
quartz sandstone?
Two Types of meta rx
 Foliated
 Non-foliated
foliated
Foliated rocks
 Increasing
grades of metamorphism
with increasing heat and pressure
 Slate-Phyllite-Schist-Gneiss
Slate–Phyllite–Schist--Gneiss
Slate-Phyllite-Schist-Gneiss
??????????????????????????????

What rock would come before slate?


What kind of rock is it?


sedimentary
What happens after gneiss? (more heat and pressure)


shale
melting
What kind of rock is it?

After cooling it is igneous
Slate
Very flat--fissile
 Used for
 pool tables
 Roofing
 they can break along
planes of weakness
(cleavage) where soft,
platy minerals like mica
and chlorite grow during
metamorphism

Phyllite
 Shiny,
wavy
surface
 Surface
has
more sheen
than slate
Schist
of mica
visible on surface
 Often has larger
mineral, like
garnet schist
 Flakes
Gneiss—
 alternating
layers
of dark and light
minerals
 Minerals align
perpendicular to
direction of force
Non-foliated

formed around
igneous intrusions
where the
temperatures are
high but the
pressures are
relatively low and
equal in all directions
(confining pressure).
Marble
 Marble
forms from
metamorphosed
limestone
 CaCO3 so it fizzes
Uses of Marble
Buildings like the
Taj Mahal
 Countertops
 Tombstones
 Statues

The Pieta—Michelangelo

Many old tombstones are made
of marble or limestone.
 Rocks
made of
calcium carbonate,
such as these
tombstones, are
readily dissolved by
rainwater.
Marble disintegrates

Marble surfaces exposed
to rain develop a rough
"sugary" texture because
the calcite grains are
loosened as the edges
dissolve in the rain water.
Column capital volute, Jefferson Memorial,
Washington, D.C.
Acid Rain




Distilled water, which contains no carbon dioxide, has a
neutral pH of 7. "Clean" or unpolluted rain has a slightly
acidic pH of 5.6, because carbon dioxide and water in the
air react together to form carbonic acid, a weak acid.
Around Washington, D.C., however, the average rain pH is
between 4.2 and 4.4.
sulfur oxides and nitrogen oxides, react with water in the
air to form strong acids (like sulfuric and nitric acid).
The main sources of these pollutants are vehicles and
industrial and power-generating plants. In Washington, the
main local sources are cars, trucks, and buses.
Quartzite
Forms from
metamorphosed
sandstone
 Often sugary
looking
 Very hard, since
it is made from
quartz

The metamorphic rock depends
on the parent rock
Metamorphic Rock Lab
Separate rocks into foliated and non foliated
 Arrange foliated rocks by increasing grade
of metamorphism


I.e.. Slate, phyllite, schist, gneiss
Test non-foliated rocks to discover which is
marble which is quartzite
 Hint: marble is metamorphosed limestone
(calcite)

For each rock test:
>6
no
no
Sugary looking quartzite
Study Guide
Use your notes!!!!!
Get on Moodle to review
Contact Metamorphism
 Rocks
that are in
contact with hot
magma or lava
often become
metamorphosed.

The metamorphic rock
that develops depends
upon the parent rock
Cooling and
crystallization
magma
Melting
Heat and
pressure
igneous
Weathering, erosion and
deposition
Sediment
Metamorphic
rock
Weathering, erosion and
deposition
WED
Cementation & compaction
Heat
and
pressure
Sedimentary rock