Transcript The Rock Cycle

The Rock Cycle
The Rock Cycle: the process that makes
new rock from old rock material; changes
rock from one type to another
• A rock is a naturally occurring mixture of
crystals of one or more minerals.
• Processes that drive the rock cycle:
– Weathering, erosion, & deposition
– Heat & pressure: increased temp. &
squeezing
Processes that drive the
Rock Cycle
• Processes that drive the rock cycle:
– Weathering, erosion, & deposition
• Weathering: Breaking down of rock by wind,
rain, ice, water, & heat
• Erosion: transport of rock
• Deposition: dropping off rock, soil, dead
animals
– Heat & pressure: increased temp. &
squeezing
Weathering: Breaking down of rock
by wind, rain, ice, water, & heat
(see an example of ice in action
below)
Weathering
Erosion
Erosion & Deposition
Weathering, erosion, & finally deposition
The Rock Cycle
Weathering & erosion
Interactive rock cycle
Three types of rocks:
• Sedimentary:
– formed from deposits by compaction &
cementation; can be formed by any type
of rock exposed at the surface of the
Earth
– Example: limestone
Sedimentary Rock
• After any type of rock is exposed on top
of the Earth & undergoes weathering,
the materials are eroded & deposited.
• This forms sed. rock through
cementation and compaction of soil,
rock, dead animals, etc. (lithification)
• Remains of plants and animals become
trapped in the layers and over long
periods of time become fossils.
• Thus, sed. rock is nicknamed fossil rock.
Compaction and Cementation
• Over time these grains and pieces of rock are
compacted and cemented together in layers.
• The compaction and cementation occurs when
sediment is squeezed by the weight of the
sediment layers above it.
• Each layer may be different from the next
layer depending on the type of sediment that is
deposited.
• Fossils are often found in sedimentary rock.
Igneous Rock
• Igneous: rocks formed from the
cooling of magma
– Two types: extrusive (think exit) &
intrusive (think inside)
– Example: pumice
Igneous Rock: Greek word for fire
• form from hot molten rock (magma)
• Melting occurs deep in the Earth near
active plate boundaries or hot spots,
then rises toward the surface.
• Two groups:
– intrusive or extrusive, depending
upon where the molten rock solidifies
Extrusive Igneous Rock
• Produced when magma exits and cools outside
of or very near the Earth's surface
• Form at erupting volcanoes
• The magma cools and solidifies almost instantly
when it is exposed to the cool temperature of the
atmosphere.
• Cooling time determines the type of rock that
forms
Pumicecooled quickly
Obsidian-cooled
slowly
Black Sand Beach: Hawaii
Intrusive Igneous Rock
• Intrusive, or plutonic, igneous rock forms when magma
is trapped deep inside the Earth.
• Great globs of molten rock rise toward the surface. Some
of the magma may feed volcanoes on the Earth's
surface, but most remains trapped below, where it cools
very slowly over many thousands or millions of years
until it solidifies.
• Intrusive igneous rock can be pushed to the surface by
plate movement.
Granite
Metamorphic Rock
• Metamorphic: sedimentary rock that
gets changed by heat & pressure as
earth’s crust is recycled
– Examples: slate & marble
Metamorphic Rock: rocks that
have changed/morphed
• Once igneous or
sedimentary rocks
• How do sedimentary
and igneous rocks
change?
– When large pieces of
crust collide, rock is
forced downward.
• Heat and pressure
squeeze the
sedimentary or igneous
rock and change it
into metamorphic rock.
Metamorphic Rocks
Shale, a sedimentary rock, is
changed by heat and pressure into
slate
shale
Limestone, a sedimentary rock, is
changed by heat and pressure into
marble. Marble is used to make
statues and countertops.
Limestone
slate
Marble
Rock Cycle Song
(Sing to the tune of "Row, Row,
Row Your Boat")
• SEDIMENTARY rock
Has been formed in layers
Often found near water sources
With fossils from decayers
• Then there's IGNEOUS rock
Here since Earth was born
Molten Lava, cooled and hardened
That's how it is formed
• These two types of rocks
Can also be transformed
With pressure, heat and chemicals
METAMORPHIC they'll become.