classification of metamorphic rocks

Metamorphic RocksMetamorphic Rocks

FORMED BY HEAT AND FORMED BY HEAT AND PRESSUREPRESSURE

OLDER ROCKS MAY BE OLDER ROCKS MAY BE FORMED INTO A NEW TYPE FORMED INTO A NEW TYPE

OF METAMORPHIC ROCKOF METAMORPHIC ROCK

- - Metamorphic rocks can form from Metamorphic rocks can form from igneous, sedimentary or other igneous, sedimentary or other

metamorphic rocks.metamorphic rocks.

EARTHQUAKES AND VOLCANIC EARTHQUAKES AND VOLCANIC ACTIVITY CAUSE HEAT AND ACTIVITY CAUSE HEAT AND

PRESSURE TO ACT ON ROCKS.PRESSURE TO ACT ON ROCKS.

- sometimes temperature and - sometimes temperature and pressure are great enough to melt pressure are great enough to melt

rock, forming magma.rock, forming magma.

- sometimes pressure flattens - sometimes pressure flattens mineral grains in rocks without mineral grains in rocks without

melting them. melting them.

- as pressure and temperature - as pressure and temperature continue to increase over time, one continue to increase over time, one type of rock can change into several type of rock can change into several

different metamorphic rocks.different metamorphic rocks.

CLASSIFICATION: 1. Foliated CLASSIFICATION: 1. Foliated texture: mineral grains flatten and texture: mineral grains flatten and line up in parallel layers or bands. line up in parallel layers or bands.

2. Nonfoliated texture: mineral 2. Nonfoliated texture: mineral grains grow and rearrange but do grains grow and rearrange but do

not form layers. not form layers.

Foliated RocksFoliated Rocks Original Rock: shale (sedimentary)Original Rock: shale (sedimentary) Metamorphic Rock: slateMetamorphic Rock: slate

Foliated RockFoliated Rock Original Rock: granite (igneous)Original Rock: granite (igneous) Metamorphic Rock: gneissMetamorphic Rock: gneiss

Nonfoliated RockNonfoliated Rock Original Rock: limestone (sedimentary)Original Rock: limestone (sedimentary) Metamorphic Rock: marbleMetamorphic Rock: marble

Nonfoliated RockNonfoliated Rock Original Rock: sandstone (sedimentary)Original Rock: sandstone (sedimentary) Metamorphic Rock: quartzite (melted Metamorphic Rock: quartzite (melted

sand)sand)

USES OF METAMORPHIC ROCK: USES OF METAMORPHIC ROCK: 1. blackboards, roofs, sidewalks, 1. blackboards, roofs, sidewalks,

floors: slatefloors: slate

2. building stone: gneiss, marble, 2. building stone: gneiss, marble, quartzite quartzite

3. statues, tombstones: marble 3. statues, tombstones: marble AND GRANITEAND GRANITE