Download unit 8: Metamorphic Rocks

unit 8: Metamorphic Rocks
Student Information
Metamorphic rock is the type of rock formed
when sedimentary rock or igneous rock undergoes a
change due to pressure or heat in the earth. Marble is
an example of a metamorphic rock. Limestone changes under heat and pressure, transforming into a new
kind of rock, marble.
Metamorphism means "change" in rocks. Heat,
pressure, and fluids that contain chemicals can convert
mineral composition in rocks, thereby forming new,
different rocks. Metamorphism can occur beneath the
surface of the earth, where the magma from the asthenosphere comes in contact with the bottom of the
crust of the earth. Here, heat is the greatest metamorphic agent. Tremendous amounts of heat and pressure
can also be found along plate lines that are converging.
Ultimately, metamorphism causes chemical changes
in the composition of the rocks. Metamorphism can
occur to varying degrees depending upon the levels/
amounts of heat, pressure, and chemically active fluids.
ated.
There are two.general classifications or families of metamorphic rocks: foliated and nonfoli-
Foliated metamorphic rocks form with layered bands. Foliated rocks are sometimes confused with sedimentary rocks because
of the layered bands. Common examples of foliated metamorphic
rocks include slate, schist, and gneiss.
foliated meamorphic rock
Nonfoliated metamorphic rocks form without layered bands.
Common examples of nonfoliated metamorphic rocks include marble and quartzite.
nonfoliated meamorphic rock