Download Metamorphic rock

 Rocks are classified by their mineral
composition and their color. Ex. Basalt
is usually a dark-colored rock with a low
silica concentration.
 Geologists observe the shape and color
of crystals in a rock to identify the
minerals that the rock contains.
 Rocks are also classified by their
texture, the look and feel of their
surface. Geologists look at grain size,
shape, and pattern.
 Geologists classify rocks into
three major groups: igneous
rock, sedimentary rock, and
metamorphic rock.
 Igneous rock forms from the
cooling of magma or lava.
 Sedimentary rock forms when
particles of other rocks or the
remains of plants and animals are
pressed and cemented together.
 Metamorphic rock forms when an
existing rock is changed by heat,
pressure, or chemical reaction.
 Extrusive rock is an igneous rock that
formed from lava. Basalt is the most
common extrusive rock found in oceanic
crust.
 Intrusive rock is an igneous rock that
formed from magma. Granite is the most
common intrusive rock found in continental
crust.
Granite
People throughout
history have used
igneous rocks for
tools and building
materials.
Basalt
 Sediment is small, solid pieces of material that
come from rocks or living things.
 Most sedimentary rocks are formed through a
series of processes: erosion, deposition,
compaction, and cementation.
 Erosion is the destructive process in which water,
wind, or gravity loosens and carries away
fragments of rock.
 Deposition is the process by which sediment
settles out of the water or wind carrying it.
 The process that presses
sediments together is
compaction. Layers of
sediments build up over
time and often remain
visible, like the
Badlands of SD.
 Cementation is the
process in which
dissolved minerals
crystallize and glue
particles of sediment
together.
 A clastic rock is a
sedimentary rock that
forms when rock
fragments are squeezed
together. EX. Shale,
sandstone, and breccia.
 Organic rock forms
where the remains of
plants and animals are
deposited in thick
layers. EX. Coal and
limestone.
Shale
Sandstone
 When minerals
that are dissolved
in a solution
crystallize,
chemical rocks
form. EX.
Limestone and
rock salt.
Coal
Rock Salt
 Geologists classify metamorphic rocks according
to the arrangement of the grains that make up
the rocks.
 Metamorphic rocks that have their grains
arranged in parallel layers or bands are said to be
foliated.
 Examples of foliated rocks: slate, schist, and
gneiss.
 Mineral grains in nonfoliated rocks are arranged
randomly and do not split into layers. EX. Marble
& quartzite.
Gneiss
Heat &
Pressure
Quartzite
Gneiss
Metamorphic
& foliated
Sandstone
Shale
sedimentary
sedimentary
Heat &
Pressure
Heat &
Pressure
Quartzite
Metamorphic &
foliated
Metamorphic
& nonfoliated
 Certain
metamorphic rocks
are important
materials for
building and
sculpture (marble &
slate).
 Marble & slate come
in a variety of colors.
Lincoln Memorial in
Washington D.C.