Ch. 3 The Rock Cycle OBJECTIVES:

• Explain the properties of each type of rock based on physical and chemical conditions under which the rock formed.

• Describe the rock cycle and how rocks change form.

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.

• Formed from particles or sediments that have

been transported & deposited by wind & water.

• Over time, these particles become pressed or cemented

together to form rocks.

• Ex: sandstone

• 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.”

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.

• 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”)

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

CHARACERISTICS OF �IGNEOUS ROCKS

CHARACERISTICS OF �SEDIMENTARY ROCKS

CHARACERISTICS OF �METAMORPHIC ROCKS