The Rock Cycle - Denton ISD

The Rock Cycle

What are Rocks? Rocks are the most common material onEarth. They are a naturally occurringcollection of one or more minerals.

The Rock Cycle a cycle that continuously forms and changes rocks

The rock cycle is used to explain how thethree rock types change to each other. Earth movement can change a rock from one type toanother through time

Convection is the driving force of therock cycle !

Rock divisions occur in three major familiesbased on how they formed: igneous,sedimentary, and metamorphic.Plate tectonic movement is responsible for the recycling of rockmaterials. As the earth’s plates slowly move, the rocks that makeup the plates are continuously recycled and change from one formto another

3 Types of RocksHow are they formed?3 Rock TypesSedimentaryWeathering and ErosionMetamorphicIgneousHeat, Pressure,Chemical ActivityMelting,Cooling,andSolidification

IGNEOUS ROCKS Igneousrocks formwhen molten rockcools and becomessolid. Molten rock is called magma when itis below the Earth’s surface. It coolsand hardens to form INTRUSIVEigneous rocks.It is lava when it is above and thencools and hardens to formEXTRUSIVE igneous rock.

Types of Igneous RocksGranite rocks areigneous rocks whichwere formed by slowlycooling pockets ofmagma that weretrapped beneath theearth's surface. Graniteis used for long lastingmonuments and for trimand decoration onbuildings.Pumice rocks are igneousrocks which were formed whenlava cooled quickly aboveground. You can see wherelittle pockets of air had been.This rock is so light, that manypumice rocks will actually floatin water. Pumice is actually akind of glass and not a mixtureof minerals. Because this rockis so light, it is used quite oftenas a decorative landscapestone.Obsidian rocks areigneous rocks thatform when lava coolsquickly above ground.Obsidian is actuallyglass and not amixture of minerals.The edges of this rockare very sharp.

SEDIMENTARY ROCKSThe forces of wind, rain,snow, and ice combine tobreak down or dissolve(weather), and carry away(transport) rocks exposed atthe surface.Rain washes rock awayLittle bits of EarthWash downstreamLayer after layerEroded Earth is pressed on topAny rock (igneous, sedimentary,or metamorphic) exposed at theEarth's surface can become asedimentary rock

Types of Sedimentary RocksSandstone rocksare sedimentaryrocks made fromsmall grains of theminerals quartzand feldspar. Theyoften form inlayers as seen inthis picture. Theyare often used asbuilding stones.Shale rock is a type ofsedimentary rock formedfrom clay that iscompacted together bypressure. They are usedto make bricks and othermaterial that is fired in akiln.Limestone rocks aresedimentary rocks thatare made from themineral calcite whichcame from the beds ofevaporated seas andlakes and from seaanimal shells. This rockis used in concrete andis an excellent buildingstone for humidregions.

METAMORPHIC ROCKSThe term "metamorphic" means "to change form."Sediment sinksPressure and HeatSediment turns into Metamorphic rockmagmaRocks metamorphosewhen they are in aplace that is very hotand pressure is highHave you heardthat caterpillarscanmetamorphoseinto butterflies?Well, rocks canmetamorphosetoo!

Types of Metamorphic RocksSchist rocks are metamorphic.These rocks can be formed frombasalt, an igneous rock; shale, asedimentary rock; or slate, ametamorphic rock. Throughtremendous heat and pressure,these rocks were transformed intothis new kind of rock.Gneiss rocks are metamorphic.These rocks may have been granite,which is an igneous rock, but heatand pressure changed it. You cansee how the mineral grains in therock were flattened throughtremendous heat and pressure andare arranged in alternating patterns.

All rock (except formeteorites!) that is onEarth today is madeof the same stuff asthe rocks thatdinosaurs and otherancient life formswalked, crawled orswam over.Over millions of years,rocks are recycled intoother rocks. Movingtectonic plates help todestroy and formmany types of rocks.While thestuff thatrocks aremadefromstays thesame, therocks donot.

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basalt, an igneous rock; shale, a sedimentary rock; or slate, a metamorphic rock. Through tremendous heat and pressure, these rocks were transformed into this new kind of rock. Gneiss rocks are metamorphic. These rocks may have been granite, which is an igneous rock, but heat and pressure changed it. You can see how the mineral grains in the