3 types of rocks.ppt

7/21/2019 3 types of rocks.ppt

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3 types of rocks



3 types of rocks• There are 3 types of

rocks found on Earth: – Igneous –

Sedimentary – Metamorphic

• Knowing thedi erences between

these 3 types ofrocks allows us tolearn about Earth spast!



Igneous "ocks # $ormation• Igneous "ocks are

formed by melting,cooling, and crystallization ofother rocks!

• Igneous rocks form asa result of volcanicactivity, hot spots,and melting thatoccurs in themantle !



Igneous rocks• Igneous rocks are common along plate

boundaries or mantle hot spots



Igneous "ocks #%lassi&cation

• Igneous rocks areclassi&ed using theirte'ture in the following

ways: – (lassy – )phanitic *no +isible

crystals, – -haneritic *+isible

crystals, – -orphyritic *Some +isible

and some not +isible

crystals,



Igneous "ocks # Te'ture• %rystal si.e is used

to classify igneousrocks!

•

%rystals form as therock cools/ and thecrystal si.e can tellus a lot about its

cooling history: – The larger the

crystals, theslower it cooled.



Igneous "ocks # Te'ture• Glassy igneous

rocks ha+e nocrystal structure/and probablyformed by +eryrapid cooling *suchas on the surface

of a la+a/ or whena la+a enters thewater!,



Igneous "ocks # Te'ture• Aphanitic rocks

ha+e no +isiblecrystals/ and

probably formed byfast cooling abo+eground!



Igneous "ocks # Te'ture• Phaneritic rocks

ha+e +isiblecrystals/ and

probably formed byslow cooling belowground!



Igneous "ocks # Te'ture• Porphyritic rocks

ha+e both +isibleand non+isible

crystals/ andprobably formed bytwo di erentcooling e+ents!




• Dark igneous rocks areformed from basaltic orma&c magma! *Ma&cbecause it contains a lotof magnesium and iron,!

• The magma that formsthese rocks is usually+ery hot *around01112%, and +iscous*about the same+iscosity as ketchup!,




• Light colored igneousrocks are formed fromsilicic *high silicacontent, or felsicmagmas!

• The magmas that formthese rocks is usuallymore cool/ *lower than

412%,/ and more+iscous *about the+iscosity of peanutbutter!,



Igneous rocks # $ormations•

Structures andformations seen inigneous rocksinclude:

– 5e'agonalcolumnar 6oints

– -ahoehoe la+a7ows

– 8ikes/ sills/ andbatholiths*plutons,

– -illow basalts – 9olcanoes



Igneous "ocks # E'amples• The most common

types of igneousrocks include:

–

"hyolite – )ndesite – asalt – Granite – 8iorite – (abbro



Igneous rocks charted



Sedimentary "ocks #$ormation

• Sedimentary rocks areformed byweathering, erosion,deposition,compaction, andcementation of otherrocks!

• Sedimentary rocks

form in areas wherewater, wind, orgravity depositsediments.



Sedimentary rocks #formation

• Sedimentary rocksare likely to form inareas such as:

–

8eltas – <eaches – "i+ers – (laciers – Sand dunes – Shallow seas – 8eep oceans



Sedimentary rocks #%lassi&cation

• Sedimentary rocksare classi&ed intotwo groups:

–

%lastic rocks – %hemically formed

rocks



Sedimentary rocks =%lassi&cation

• Sedimentary rocksare !lastic if theyare made of piecesof other rocks thatha+e beenweathered anderoded!

•

%lastic rocks aregrouped based onthe si.e of grain thatthey are made from!




• 9ery small particlesmake up mudrock!

• Medium si.ed

particles make upsandstone!

• >arge particlesmake upconglomerates!




• Sedimentary rocksthat form fromchemical processes

are calledbiochemical rocks*formed from li+ingthings, or !hemical

precipitates*formed from lakesor shallow seas!,



Sedimentary rocks #formations

• Structures andformations seen insedimentary rocks

include: – Strati&cation – %ross bedding – (raded bedding – "ipple marks – Mud cracks – $ossils



Sedimentary rocks #E'amples

• Some of the mostcommon types ofsedimentary rocksinclude:

– %onglomerate – Sandstone – Shale – >imestone – (ypsum – ?olites – %hert *including black

7int and red 6asper,



Sedimentary rocks # Story• hat do you know

about the history ofthe Earth in the

place where thisrock was found;



Metamorphic rocks #$ormation

• Metamorphic rocksare formed by heatand pressure changing one type ofrock into anothertype of rock!

• Metamorphic rocksform near lavaintrusions / at platesubduction zones /and in deepmountain roots !




• >a+a intrusions canpro+ide heat thatcauses

metamorphic rocksto form! Thesesmall areas ofmetamorphic rock

form from contactmetamorphosis.




• "ocks thatmetamorphosebecause ofincreasing heat andpressure found atplate subduction.ones and in deepmountain roots form

large areas ofmetamorphic rockthrough regionalmetamorphosis.



Metamorphic rocks #%lassi&cation

• Metamorphic rocksare classi&ed into @ma6or groups:

–

$oliated – Aonfoliated



Metamorphic rocks #%lassi&cation

• "oliated rocks form whendi erential pressurecauses minerals to formin layers!

• These rocks will ha+estripes or planes that theywill break easily along!

• These BstripesC don tusually line up with theoriginal bedding planes insedimentary rocks!



Metamorphic rocks• #on$oliated

metamorphic rocksformed in areas

where the pressurefrom all sides waseDual/ so there isno BlinearC Duality

to the rocks!



Metamorphic rocks #$ormations

• Structures andformations seen inmetamorphic rocks

include: – $olding – -lastic deformation – Stretching – )lternating dark

and light layers*gneissic foliation,



Metamorphic rocks #E'amples

• Some common typesof metamorphic rockinclude:

– Slate – Schist – (neiss – )mphibolite –

Marble – uart.ite – Metaconglomerate



Metamorphic rocks #%harted



Metamorphic rocks # story• hat do you know

about the history ofthe Earth in the

place where thisrock was found;

3 types of rocks.ppt

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