IV. METAMORPHIC ROCK
- metamorphism – the process in which one type of rock
changes into metamorphic rock because of chemical processes
or changes in temperature and pressure
A. Formation of Metamorphic Rock
1. heat, pressure and hot fluids cause some minerals to
change into other minerals
2. minerals may change in size and shape
3. minerals may separate into parallel bands
4. type of rock may indicate conditions the rock formed
under
5. Contact Metamorphism
a. a change in the structure or chemical composition of
a rock due to contact with magma
b. only a small volume of rock that surrounds the
magma is changed
6. Regional Metamorphism
a. a change in the structure or chemical composition of
a rock due to changes in temperature and pressure
over a large area, generally as a result of tectonic
forces
b. tremendous heat and pressure at the edge of rocks
during tectonic activity
c. heat and pressure cause chemical changes in the rock
d. most metamorphic rock is formed this way
B. Classification of Metamorphic Rock
1. foliated rocks
a. foliation – the metamorphic rock texture in which
mineral grains are arranged in planes and bands
b. slate, schist and gneiss
2. Non-foliated Rocks
a. non-foliated – the metamorphic rock texture in
which mineral grains are not arranged in planes or
bands
b. quartzite, marble, granite