Rocks and the Rock Rocks and the Rock CycleCycleLEQ: How have different processes LEQ: How have different processes created the mineral and rocks that created the mineral and rocks that are found in Earth’s crust?are found in Earth’s crust?

RocksRocks

Rocks are Rocks are made of made of minerals minerals from Earth’s from Earth’s crust and crust and mantle.mantle.

Igneous RocksIgneous Rocks

Also known as firestones Also known as firestones because they form from because they form from either magma or lava.either magma or lava.

Intrusive Igneous Rocks Intrusive Igneous Rocks form below Earth’s form below Earth’s surface (magma).surface (magma). Cools slowly and form Cools slowly and form

large mineral crystalslarge mineral crystals Ex: Granite, Diorite, Ex: Granite, Diorite,

GabbroGabbro

Igneous RocksIgneous Rocks

Extrusive Igneous Extrusive Igneous Rocks form above Rocks form above Earth’s surface Earth’s surface (Lava).(Lava). Cools quickly and Cools quickly and

forms small crystals forms small crystals or no crystals (glass).or no crystals (glass). Ex: Obsidian, Basalt, Ex: Obsidian, Basalt,

RhyoliteRhyolite

Igneous RocksIgneous Rocks

Along with crystal size, igneous rocks Along with crystal size, igneous rocks are also classified by color or mineral are also classified by color or mineral composition.composition. Mafic rocks are dark in color and usually Mafic rocks are dark in color and usually

contain the minerals OLIVINE OR contain the minerals OLIVINE OR CALCIUM PLAGIOCLASE.CALCIUM PLAGIOCLASE. Example: Basalt from the black beaches of Example: Basalt from the black beaches of

HawaiiHawaii

Igneous RocksIgneous Rocks

Intermediate rocks are Intermediate rocks are dark and light in color dark and light in color (Dalmatian speckled).(Dalmatian speckled). Ex. DioriteEx. Diorite

Felsic rocks are light in Felsic rocks are light in color and usually contain color and usually contain minerals quartz and minerals quartz and muscovite (high in silica).muscovite (high in silica). Ex. RhyoliteEx. Rhyolite

Sedimentary RocksSedimentary Rocks

Formed from the processes of erosion, Formed from the processes of erosion, deposition, compaction, and lithofication.deposition, compaction, and lithofication. Erosion: Breaking up and wearing down rocks.Erosion: Breaking up and wearing down rocks. Deposition: Rock sediments sinking to the bottom of Deposition: Rock sediments sinking to the bottom of

lake, river, ocean, glacial deposits.lake, river, ocean, glacial deposits. Compaction: Pressing sediments together.Compaction: Pressing sediments together. Lithofication: Process where dissolved minerals Lithofication: Process where dissolved minerals

crystallize and “glue” sediments together.crystallize and “glue” sediments together.

Classification of Classification of Sedimentary RocksSedimentary Rocks

Chemical CompositionChemical Composition Clastic: formed from the Clastic: formed from the

cementation (lithofication) cementation (lithofication) of other rock sedimentsof other rock sediments

Chemical: formed from Chemical: formed from precipitation out of precipitation out of solution.solution. Ex. Rock Salt or some Ex. Rock Salt or some

forms of limestone forms of limestone (caves)(caves)

Organic: formed from the Organic: formed from the remains of once living remains of once living creatures.creatures. Ex. Coal, Coquina Ex. Coal, Coquina

(special limestone from (special limestone from shells)shells)

Classification of Classification of Sedimentary RocksSedimentary Rocks

Rock TypeRock Type Fragment SizeFragment Size

BrecciaBreccia Fragments are > 2mm(gravel) in Fragments are > 2mm(gravel) in size, fragments are jagged.size, fragments are jagged.

ConglomerateConglomerate Fragments are > 2mm (gravel) in Fragments are > 2mm (gravel) in size, fragments are rounded.size, fragments are rounded.

SandstoneSandstone Fragments are 1/16-2mm in sizeFragments are 1/16-2mm in size

SiltstoneSiltstone Fragments are1/16-1/256mm in Fragments are1/16-1/256mm in sizesize

ShaleShale Fragments are <1/256 mm in size Fragments are <1/256 mm in size (clay)(clay)

MudstoneMudstone Composed of 50% shale and Composed of 50% shale and 50%silt50%silt

Limestone/CoquinaLimestone/Coquina Formed from skeletons of corals Formed from skeletons of corals and mollusksand mollusks

Metamorphic RocksMetamorphic Rocks

Form from heat and Form from heat and pressure applied to pressure applied to igneous, sedimentary or igneous, sedimentary or other metamorphic other metamorphic rocks.rocks.

Metamorphic ProcessesMetamorphic Processes Contact Metamorphism is Contact Metamorphism is

when an igneous intrusion when an igneous intrusion (magma) causes (magma) causes surrounding rock to surrounding rock to “bake”.“bake”. Pressure is not a factor.Pressure is not a factor.

Metamorphic RocksMetamorphic Rocks

Regional Regional Metamorphism is Metamorphism is when heat from when heat from pressure causes pressure causes metamorphism.metamorphism. Often seen in events Often seen in events

such as continental such as continental collisions.collisions.

Types of Metamorphic Types of Metamorphic RocksRocks

Foliated Rocks: Rocks Foliated Rocks: Rocks that have grains that have grains arranged in parallel arranged in parallel layers or bands.layers or bands. Gneiss, SlateGneiss, Slate

Non-Foliated: Rocks that Non-Foliated: Rocks that have mineral grains have mineral grains arranged randomly.arranged randomly. Marble or quartziteMarble or quartzite

Rock CycleRock Cycle