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