Ch. 3 The Rock Cycle

Columns of rock called

hoodoos dot Bryce

Canyon National Park.

Magma - molten material deep

beneath Earth’s surface.

Lava - magma that reaches the surface.

***The melting of any rock type leads to the

production of magma.

Formation• Igneous Rocks form when Magma or lava Cools.

• Cooling can occur either

below or above the surface!

Formation of Igneous Rocks

Intrusive - magma hardens

beneath Earth’s surface (granite). Cools slowly

Have large crystals/grains

Extrusive - formed when lava

hardens at surface (pumice, rhyolite). Cools quickly

Have no/small crystals/grains

Weathering - rocks broken down by water,

air & living things.

Sediments -weathered pieces

of Earth elements. Erosion - sediments are transported by

water, wind or gravity.

produces

Are moved by

• Formed from particles or sediments that have been

transported & deposited by wind, water, ice, gravity.

• Over time, these particles become pressed or cemented together to form

rocks.

• Ex: sandstone

Clastic

Clastic vs Chemical Sedimentary Rocks

• After weathering and Erosion occur sediments must be deposited!

• Deposition - an agent of erosion (water, wind, ice, or gravity) loses

energy & drops sediments.

Formation of Sedimentary Rocks 1. Weathering, Erosion & Deposition

2. Compaction & Cementation

• Compaction - process that squeezes sediments by the weight of

overlying materials driving out water.

• Cementation – Solidification of sediments by the deposition of

dissolved minerals which act like a “glue.”

• Formed when chemical reactions, heat, and/or pressure change

existing rocks into new rocks.

(physical & chemical properties usually quite different from original.)

meta- means change, morph means form.

(Ex: marble, schist, gneiss (pronounced “nice”)

Agents of Metamorphism Heat - provides energy needed to drive chemical reactions.

Pressure - causes a more compact rock with greater density.

How does this happen ?

Contact metamorphism:

magma moves into rock

• Occurs near a body of magma

• Changes are driven by a rise in

temperature

Regional metamorphism:

large-scale deformation• Direct pressures occur during

mountain building

• Produces greatest volume of

metamorphic rock.

Energy That Drives the Rock

Cycle Processes driven by heat from Earth’s

interior are responsible for forming

both igneous & metamorphic rocks.

Weathering & erosion are external

processes powered by energy from the

Sun, produce sedimentary rocks.

IGNEOUS ROCKS

SEDIMENTS

SEDIMENTARY

ROCKS

METAMORPHIC

ROCKS

MAGMA

Weathering and erosionHeat and pressureMeltingCooling

Compaction,

cementation, and

lithification