LITHOSPHERE ROCK CYCLE
Theage of PlanetEarth ... • Earth is about4,6 billionyearsold! • In the beginning Earthconsisted of moltenmetal and rocks. • Heavymetalssunkdeeper and lightermetalsfloatedatthe top.
Earth is ahugeball and consists of fourconcentriclayers Crust Mantle Outercore Inner core
THE CRUST • Thecrust of theearthlookssolid, butmovesconstantlyonthemoltenmantle. • Thecrust is dividedintohugeplates, thetectonicplates. • Thecrusts of thecontinentsconsistofgranite and quartz, whiletheoceaniccrustconsists of basalt. • Theoutermostlayer of themantle and thecrustformthelithosphere.
Threemaintypes of rock • Igneousrock • Sedimentaryrock • Metamorphicrock
Igneousrock • FromGreek word meaning„fire”. • Moltenrock is called magma. • Whenmagma coolsdown and solidifies, igneousrockis formed. • Graniteformswhen magma coolsslowly and form big crystals. • Basalt and pumiceformwhen magma coolsfaster and formsmallcrystals. • Pumice also hasmanyholes – spacesfilledwith air/ bubbleswhenstill hot.
SEDIMENTARY ROCK – it is difficulttobelievethatthe Karoo was onceaninlandsea, untilyou see the koppies and layers of sedimantaryrock
Different types of sediment form different types of sedimentaryrock
Sedimentaryrock • Sedimentaryrockformswhenrockfragments and mineralparticlessettleatthebottom of thesea, alakeorariver. • Overtimethelayers of sand, silt and claybecomecementedtogetherunderhighpressure. • Sandstone, shale and limestone are examples of sedimentaryrock.
Metamorphicrock • Metamorphicrockformswhenigneousorsedimentaryrock are heatedor put underhighpressurefor a long time. • Marble and slate are metamorphicrocktypesthatcamefromsedimentaryrock put underheat and pressure.
Marble • Marble formswhenlimestone, asedimentaryrock, undergoesheat and pressure. • Themainmineral in marble (and limestone) is calciumcarbonate (CaCO3), givingitawhitecolour. • Thecolours of marble are duetootherminerals e.g. red marblecontainsironoxide.
White marblequarry in Tuscany Statue of Herakles