3.4 3.4 MetamorphicMetamorphic rocks rocks

formform as as existingexisting rocks rocks changechange

Classifying RocksClassifying Rocks

33 rock types rock types SedimentarySedimentary IgneousIgneous MetamorphicMetamorphic

MetamorphismMetamorphismThe process by which The process by which existing existing rock is rock is changedchanged by by pressurepressure or or heatheat

Metamorphic RocksMetamorphic Rocks

““changechange””

Igneous and sedimentary rocks that have Igneous and sedimentary rocks that have changedchanged due to due to heatheat and and pressurepressure

Heat and pressure cause Heat and pressure cause newnew combinations or new crystals to formcombinations or new crystals to form **heating and cooling of in **heating and cooling of in mantlemantle layer layer

may lead to this formationmay lead to this formation

MetamorphicMetamorphic

Parent RockParent Rock The The originaloriginal rock went through rock went through

metamorphismmetamorphism. (the rock . (the rock changedchanged)) Ex: Ex: igneousigneous rock and rock and sedimentarysedimentary rock rock

“melting” together to form this new “melting” together to form this new metamorphic rock)metamorphic rock)

A metamorphic rock A metamorphic rock CANCAN be a be a parentparent to another metamorphic to another metamorphic rock rock One rock, “melting” and turning into One rock, “melting” and turning into

anotheranother

Changes in Changes in MetamorphismMetamorphism

Rocks may Rocks may flattenflatten and and pushedpushed together together

Rocks may “Rocks may “meltmelt” ” together to form together to form newnew rocks rocks

RecrystallizationRecrystallizationThe process by which The process by which bondsbonds between between atomsatoms in in mineralsminerals break and break and re-formre-form in in newnew ways during ways during metamorphismmetamorphism

Bands in RocksBands in RocksFoliationFoliation:: the the arrangementarrangement of of mineralsminerals in in flatflat or wavy parallel or wavy parallel bandsbands..

Found in rocks made of Found in rocks made of

22 or or moremore minerals minerals

Foliated metamorphic Foliated metamorphic rocksrocks

Slate Slate GneissGneiss

NonfoliatedNonfoliated Rock RockMetamorphic rock Metamorphic rock withoutwithout foliation (bands/stripes)foliation (bands/stripes)

Primarily made of Primarily made of 11 mineral mineralNotNot subject to high subject to high pressurepressure

Non foliated Non foliated metamorphic Rocksmetamorphic Rocks

Marble QuartziteMarble Quartzite

Brain PopBrain Pop

http://www.brainpop.com/science/earthsystem/typesofrocks/preview.weml

DiscussionDiscussion

What is metamorphism?What is metamorphism? It is any process that affects the It is any process that affects the

structure or composition of a rock in a structure or composition of a rock in a solid state as a result of changes in solid state as a result of changes in temperature, pressure, or the addition of temperature, pressure, or the addition of chemical fluids.chemical fluids.

Under what conditions do Under what conditions do metamorphic rocks form?metamorphic rocks form? Metamorphic rocks can form due to Metamorphic rocks can form due to

changes in temperature and pressure.changes in temperature and pressure.

DiscussionDiscussion

What type of metamorphic rock has What type of metamorphic rock has layers?layers? Foliated metamorphic rock has layers Foliated metamorphic rock has layers

(stripes).(stripes).

ChallengeChallenge

Refer to book…Refer to book… Compare and contrast contact Compare and contrast contact

metamorphism and regional metamorphism and regional metamorphism.metamorphism. Contact metamorphism occurs where Contact metamorphism occurs where

magma comes in contact with parent magma comes in contact with parent rock. Regional metamorphism occurs rock. Regional metamorphism occurs over a much larger area and results from over a much larger area and results from increases in pressure and temperature increases in pressure and temperature and chemical fluids.and chemical fluids.