Metamorphic Rocks
FORMED BY HEAT AND
PRESSURE
OLDER ROCKS MAY BE
FORMED INTO A NEW TYPE
OF METAMORPHIC ROCK
- Metamorphic rocks can form from
igneous, sedimentary or other
metamorphic rocks.
EARTHQUAKES AND VOLCANIC
ACTIVITY CAUSE HEAT AND
PRESSURE TO ACT ON ROCKS.
- sometimes temperature and
pressure are great enough to melt
rock, forming magma.
- sometimes pressure flattens
mineral grains in rocks without
melting them.
- as pressure and temperature
continue to increase over time, one
type of rock can change into several
different metamorphic rocks.
METAMORPHIC ROCKS ARE
CLASSIFIED BY Composition AND
TEXTURE
CLASSIFICATION: 1. Foliated
texture: mineral grains flatten and
line up in parallel layers or bands.
2. Nonfoliated texture: mineral
grains grow and rearrange but do
not form layers.
Foliated Rocks
 Original
Rock: shale (sedimentary)
 Metamorphic Rock: slate
Foliated Rock
 Original
Rock: granite (igneous)
 Metamorphic Rock: gneiss
 Original
Nonfoliated Rock
Rock: limestone (sedimentary)
 Metamorphic Rock: marble
 Original
Nonfoliated Rock
Rock: sandstone (sedimentary)
 Metamorphic Rock: quartzite (melted
sand)
USES OF METAMORPHIC ROCK:
1. blackboards, roofs, sidewalks,
floors: slate
2. building stone: gneiss, marble,
quartzite
3. statues, tombstones: marble
AND GRANITE