RocksRocks

Pieces of the Earth’s crust.Pieces of the Earth’s crust.

Types of RocksTypes of Rocks

• Igneous- Rocks that formed from the fiery depths of the Earth. They form from magma and lava.– Extrusive– Intrusive

• Sedimentary- Rocks that formed from the eroded sediment of other rocks through lithification (compaction, cementation)

• Metamorphic- Rocks that have been changed or morphed through heat and pressure

Igneous RockIgneous Rock

• Rock that forms from cooled magma or lava.

• Crystalline or glassy structure

• Extrusive or Intrusive

• Felsic- Thick viscous, silica rich, light colored

• Mafic- Hot, thin, fluid-like, often Iron rich, dark colored

Igneous RockIgneous Rock

• Igneous Rock Examples

Igneous RockIgneous Rock

• Structure depends upon freezing temperature of rock and rate of cooling

• Bowen’s reaction series– High freezing temperatures crystallize first– Depends upon composition– Discontinuous series- Mafic magma

• Olivine, pyroxine, amphibole, biotite, potassium feldspar, muscovite, quartz

– Continuous series- Felsic magma• Calcium rich, calcium/sodium rich, sodium rich

Bowen’s Reaction SeriesBowen’s Reaction Series

Igneous RocksIgneous Rocks

• Crystal size depends upon rate of cooling

• Fast cooling lava produces small crystals, or even no crystals (glassy)

• Slow cooling magma produces large crystals.

• When magma cools at different rates, large and small crystals may result creating porphoritic rock

Igneous RocksIgneous Rocks

• Rock Families– Read about the 3 main types of rock families

in your text. pgs 123-125– Summarize each type of igneous rock family

in your notes

Igneous FamiliesIgneous Families

• Granite (Felsic)

• Gabbro (Mafic)

• Diorite (Intermediate)

• Peridotite (Ultramafic)

Granite FamilyGranite Family

• Mostly coarse grained felsic rocks that are generally light in color. Most granite family rocks cool slowly due to the thick sticky magma that they form from.

Gabbro FamilyGabbro Family

• Dark, dense coarse grained mafic rocks.

• Contain the minerals pyroxene, olivine, plagioclase feldspar, amphibole, and biotite.

Diorite FamilyDiorite Family

• A mixture of felsic and mafic rock.

• Darker than granites but lighter than gabbros.

Peridotite FamilyPeridotite Family

• Dense coarse grained ultramafic rock.

• Contain the minerals olivine and pyroxene.

Sedimentary RocksSedimentary Rocks

• Sedimentary rocks form from fragments of other rocks producing clastic rocks.

• Through weathering and erosion, sediment is carried by wind and water.

• This sediment is eventually deposited.

• Deposition occurs when the moving water or wind slows down.

Sedimentary RockSedimentary Rock

• Deposited material often gets sorted by size.

• Large sediment often only makes it part way down rivers.

• Small sediment makes it to the mouth of rivers.

• Fine silts and clays gets carried out to the middle of the oceans and lakes

Sedimentary RockSedimentary Rock

Sedimentary RocksSedimentary Rocks

• Eventually material is formed into rock through lithification

• This sorting gives rise to different types of clastic rock such as– Conglomerate– Sandstone– Shale

ConglomerateConglomerate

SandstoneSandstone

The layering that is shown here is called stratification.

ShaleShale

Sedimentary RockSedimentary Rock

• Other types of sedimentary rock can be formed through chemical processes and organic material– Limestone (organic and chemical)– Halite (chemical)– Coquina (organic)

LimestoneLimestone

HaliteHalite

CoquinaCoquina

Sedimentary RockSedimentary Rock

• Sedimentary Rock Examples

Metamorphic RockMetamorphic Rock

• Metamorphic rock is rock that has been changed over time due to heat and pressure.

• Crystals get squished and the texture becomes foliated

• Foliated metamorphic rocks have a layered or banded appearance that is produced by exposure to heat and directed pressure.

Metamorphic Rock FoliationMetamorphic Rock Foliation

Crystal are flattened

Orientation becomes aligned

Metamorphic RockMetamorphic Rock

• Metamorphic Rock Examples

• Foliation process animation