Download The Rock Cycle

Cycle
Rock
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Rock
Cycle
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let’s review some basic information …
Adapted from a Powerpoint by Michigan Department of Environmental Quality
Geological Survey Division - http://www.deq.state.mi.us/gsd
Natural elements
and compounds
are minerals.
Elements combine to
make compounds.
Rocks are mixtures
of minerals.
Rocks make the Earth
The Earth is made of 3
kinds of rock that are
recycled in the
Rock Cycle
Sedimentary Metamorphic
Rocks
Rocks
Igneous
Rocks
Igneous Rocks
Sedimentary Rocks
Metamorphic Rocks
Enough about rocks,
on to the cycle
…
James Hutton
Developed the Rock Cycle
explaining that rocks don’t
stay the same forever;
natural physical processes
cause them to change from
one type to another.
The Rock Cycle.
Rocks are neither created nor destroyed, they just
change from one type to another.
Sedimentary
weathering
Igneous
The Rock Cycle
does not go in
Metamorphic
just one
direction.
Any given rock
can go through
any part of the
cycle any number
of times.
The Earth can be thought of as a
giant recycling machine
http://www.science.ubc.ca/~geol202/rock_cycle/rockcycle.html March 2000
Google “rock cycle”
Rock cycles
Igneous Rocks
Igneous Rocks
Igneous Rocks
Formed from
molten material
Igneous= made from fire
Mt. St. Helens
Videocam
• Igneous rocks start
as molten rock or
magma which may
become solid before
ever reaching the
surface
• Sometimes magma is
full of gases like a pop
with the cap on.
• When magma reaches
the surface pressure
is released, gases
begin escaping and it’s
lava
Igneous Rock
• Crystals interlock (grew together )
forming a strong rock.
• Magma cools slowly and crystals have
time to grow.
• Lava cools quick and the crystals
don’t have time to grow so they’re
small or there are none.
• Bigger crystals = slower cooling =
deeper
Crystal Size
Rate of cooling
determines size
of crystals
Fast cooling: no
crystals or small
crystals
Slow cooling:
large crystals
Extrusive: Cool Fast
No Crystals
.
Extrusive: Cool Fast
Small Crystals
Examples:
Extrusive
• Obsidian
Examples: Extrusive
• Pumice
Examples: Extrusive
• Basalt
Intrusive: Cool slowly
• Large crystals
Examples: Intrusive
• Granite
Clues it’s Igneous
• If crystals are large, the colors
are randomly spread.
• If crystals are small, the color is
even and there may be an
occasional big crystal
• May have bubbles
• May be made of broken fragments
• May be glass.
Sedimentary Starts with Rocks Being
Broken into Smaller Pieces
• Heating and
cooling causes
rock to expand
and shrink.
• Water gets into
cracks, freezes
and expands,
splitting the rock.
• Lichens & plants
make acids that
dissolve rock.
Plant roots split
rock.
A process called
weathering
Weathered Rock Erodes
• Wind, water and gravity, cause
weathered rock to erode
• Eroding fragments of rock get
smaller and more rounded the
more they erode.
• Faster water can carry bigger
fragments, pieces settle out as
the current slows and the water
deepens.
Sediment Deposition
• Sediment Becomes Rock
• New layers are always on top of old layers
• Sediment builds up and increased weight causes
sediment to compact
• Minerals grow between compacted pieces turning them
into rock
Sedimentary Rocks
Sed. Rocks often form into layers
From Sediment to Rock
• Most sedimentary rocks are formed through a
series of processes: erosion, deposition,
compaction, and cementation.
Clues it’s Sedimentary
• Earthy colors (browns, oranges, reds,
black, gray, white, clear, sand, mauve,
buff, tan, etc.)
• Rounded pieces
• Fossils
Metamorphic
Pressure, heat and fluids
cause preexisting
materials to become
Metamorphism
metamorphic rocks
Metamorphic mountain
ranges like the Rockies, Alps
and Himalayas are caused by
colliding plates
Himalaya
formation
Rocks
Metamorphic Rock
Metamorphism: Changing of one type
of rock to another by:
Heat
Pressure
Chemical reactions
Metamorphism makes rocks
stronger or more resistant
Contact Metamorphism
–hot magma pushes through
existing rock, heating
surrounding rock and changing it
to metamorphic.
Classification of
Metamorphic rock
Foliated
&
Non-foliated
Foliated Rocks:
• Have visible layers
• Mineral grains are flattened and aligned
when pressure is added
PRESSURE
Gneiss has banded foliation
Granite
Gneiss
Gneiss
Slate has banded foliation
Shale
Slate
Slate
Slate
Non-foliated Rocks:
• These DO NOT have layers of
crystals.
Quartzite has no foliation (layers)
Sandstone
Quartzite
Quartzite
Marble has no foliation (layers)
Limestone
Marble
Marble
• Unfinished Marble
• Finished Marble
Clues it’s Metamorphic
• Often black and white, or green.
• May be red (garnet) or shiny
(mica)
• Often foliated (lines)