Igneous rocks ► Crystallize from a molten rock: magma ► Magma: liquid rock beneath earth’s surface ► Lava: liquid rock above earth’s surface ► Igneous.

Igneous rocksIgneous rocks

►Crystallize from a molten rock: magmaCrystallize from a molten rock: magma►Magma: liquid rock Magma: liquid rock beneathbeneath earth’s earth’s

surfacesurface►Lava: liquid rock Lava: liquid rock aboveabove earth’s surface earth’s surface► Igneous rocks classified on Igneous rocks classified on

Mineral sizeMineral size compositioncomposition

Igneous rocksIgneous rocks

► IntrusiveIntrusive igneous rocks igneous rocks Cool below ground (slowly)Cool below ground (slowly) All minerals visible w/out microscopeAll minerals visible w/out microscope

►ExtrusiveExtrusive igneous rocks igneous rocks Cool above ground (fast)Cool above ground (fast) Most minerals too small to see w/out Most minerals too small to see w/out

microscopemicroscope

Igneous rocksIgneous rocks

► Intrusive igneous rocksIntrusive igneous rocks►Extrusive igneous rocksExtrusive igneous rocks

Intrusive or extrusive?Intrusive or extrusive?

Slow or fast cooling?Slow or fast cooling?

Intrusive or extrusive?Intrusive or extrusive?

Slow or fast cooling?Slow or fast cooling?

Light colored igneous rocksLight colored igneous rocks

►Granite and rhyoliteGranite and rhyolite

Intermediate igneous rocksIntermediate igneous rocks

► AndesiteAndesite

Dark colored igneous rocksDark colored igneous rocks

►Gabbro and basaltGabbro and basalt

Aphanitic Texture – Rapid Cooling Small Crystals

Phaneritic Texture – Slow Cooling Large Crystals

Glassy Texture - Very Rapid Cooling - No Crystal Structure

Where do igneous rocks form?

What is left behind when igneous rocks cool?

Rock CycleRock Cycle► Igneous rocks can become what other kind of rocks?Igneous rocks can become what other kind of rocks?

Metamorphic rocks

►Formed by transformation of other rocks

►Heat and pressure do this transforming!

►End up with New minerals And/or texture changes

Metamorphic textures►Foliated:

alignment of minerals Rock looks

banded/layered

►Nonfoliated: random orientation of minerals

Foliated or nonfoliated?

Foliated metamorphic rocks

►Smallest minerals

►Slate►Clue: like

shale/mudstone but harder

Foliated metamorphic rocks

►Schist►Shiny with

bigger minerals

Foliated metamorphic rocks

►Gneiss►Big minerals►Looks like a

granite with bands of color

Nonfoliated met. rocks

►Marble►Made of calcite►Best way to ID?

Nonfoliated met. rocks

►Quartzite►Can look like

marble, but no fizz with acid

Nonfoliated met. rocks

►Greenstone►Clue: green

basalt

Rock Cycle

Sedimentary rocksSedimentary rocks

►ClasticClastic sed rock: made of solid sed rock: made of solid particles once part of other rocksparticles once part of other rocks Classified by grain sizeClassified by grain size

►ChemicalChemical sed rock: made from sed rock: made from dissolved material in waterdissolved material in water Classified by chemical compositionClassified by chemical composition

►BiochemicalBiochemical sed rock: made of dead sed rock: made of dead plants and animalsplants and animals

Biochemical, chemical, or Biochemical, chemical, or detrital?detrital?

ClasticClastic sed rocks sed rocks►Big particlesBig particles Conglomerate Conglomerate►Sand size SandstoneSand size Sandstone►Small particles Mudstone (shale)Small particles Mudstone (shale)

Clastic sed rocksClastic sed rocks

►ConglomerateConglomerate►Clue: Clue:

Particles of Particles of lots of lots of different sizesdifferent sizes

Clastic sed rocksClastic sed rocks

►SandstoneSandstone►Clue: feels Clue: feels

sandysandy

Clastic sed rocksClastic sed rocks

►Mudstone Mudstone (shale)(shale)

►Clue: Clue: very small very small

particlesparticles No grit when No grit when

you taste ityou taste it

Chemical sed rocksChemical sed rocks

►LimestoneLimestone Made of calciteMade of calcite Clues: Clues:

►fizzes with acid fizzes with acid

►Often contains Often contains fossilsfossils

Chemical sed rocksChemical sed rocks

►Rock salt/haliteRock salt/halite Clue: tastes Clue: tastes

saltysalty►GypsumGypsum

Clue: easily Clue: easily scratched, not scratched, not saltysalty

Biochemical sed rocksBiochemical sed rocks

► Category of Category of chemical sed rockschemical sed rocks

► CoalCoal► Limestone if with Limestone if with

fossilsfossils

Importance of sed rocksImportance of sed rocks

►Key to interpreting Earth’s historyKey to interpreting Earth’s history

Homework

►Go to website and complete the relative age assignment.

►Other website for checking to see if you are on the right track!

►Websites are on our class page