The Rock Cycle

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The Rock Cycle

• By
• Sarah Dowling
• Rupa Kamboj
• Joy Kim
• Tony Tavlian
• Jean Young

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Basics

• The Rock Cycle is a group of changes in which
• Igneous rock can change into sedimentary rock or
  into metamorphic rock
• Sedimentary rock can change into metamorphic rock
  or into igneous rock.
• Metamorphic rock can change into igneous or
  sedimentary rock.

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Igneous Rock

• Igneous rock is formed when magma cools and makes
  crystals.
• Magma is a hot liquid made of melted minerals.
  The minerals can form crystals when they cool.
• Igneous rock can form underground, where the
  magma cools slowly or igneous rock can form above
  ground, where the magma cools quickly.

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Igneous Rock
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Sedimentary Rock

• Sedimentary rocks form at or near the earth's
  surface at relatively low temperatures and
  pressures primarily by
• deposition by water, wind or ice
• precipitation from solution (may be biologically
  mediated)
• growth in position by organic processes (e.g.,
  carbonate reefs )

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Sedimentary Rock
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Metamorphic Rock

• Metamorphic Rock is formed when rocky material
  experiences intense heat and pressure in the
  crust of the earth.
• Through the metamorphic process, both igneous
  rocks and sedimentary rocks can change into
  metamorphic rocks, and a metamorphic rock can
  change into another type of metamorphic rock.
• Heat and pressure do not change the chemical
  makeup of the parent rocks but they do change the
  mineral structure and physical properties of
  those rocks.

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Metamorphic Rock
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Pause Here
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Sediment

• Sediment can either be
• Material, originally suspended in a liquid, that
  settles at the bottom of the liquid when it is
  left standing for a long time
• Material eroded from preexisting rocks that is
  transported by water, wind, or ice and deposited
  elsewhere

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Sediment
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Plutonic and Volcanic Rock

• Volcanic rocks, a.k.a extrusive rocks or lava
  rocks, crystallize when the magma reaches the
  earths surface cooling quickly.
• Plutonic or intrusive rocks crystallize within
  the crust of the earth, and as a result plutonic
  rocks cool at a much slower pace then volcanic
  rocks

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Melting

• Melting is the result of continued heating
• Leads to production of magma and new igneous
  rocks which are formed when the the magma cools.
• This process depends on the size of the reservoir
  that it drains and the relative intensity or
  activity of plate tectonics.

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Heat and Pressure

• Metamorphic rocks trapped underground are still
  subject to enormous heat from rising magma, or
  heated water, and pressure. Sometimes the heat
  can get so intense the rocks actually melt.
• Pressure comes from the incredible weight of
  material surrounding the rock on all sides.
• The pressure pushes new minerals into the rock
  and drives other minerals out the result, of
  course, is that the rock is chemically changed.

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Weathering

• The process in which rocks are broken down by
  chemical and/or physical mechanisms into smaller
  particles.
• There are three types of weathering
• Physical weathering physical action which breaks
  up rocks. An example of this is freethaw
  weathering
• Chemical Weathering when the rock is attacked by
  chemicals. An example of this is how acid rain
  breaks down limestone.
• Biological weathering occurs when rocks are
  weakened and broken down by animals and plants. A
  tree root system that is slowly splitting rocks
  is an example of this type of weathering..

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Erosion

• Erosion is the wearing away of exposed surfaces
  by agents such as wind, moving water and ice.
  These agents usually contain weathered rock
  debris. Rock fall under gravity is also erosion.
• Erosion influences orogenesis by changing the
  topography and hence the thickness of the
  deforming orogen, which, in turn results in
  modification of the gravitational force relative
  to the tectonic driving force. Whereas efficient
  erosion tends to localize deformation within a
  relatively narrow belt, decrease in erosional
  efficiency causes deformation to propagate toward
  more distal sites.

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Erosion
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Subduction

• A rock that gets caught up in the subduction
  zone may get dragged down with the oceanic plate.
  
• As the rock gets dragged down, they undergo
  metamorphism.
• Some parts of the rocks get taken all the way
  down to the mantle where they slowly mix with the
  rest of the mantle. this is the only way that
  rocks formed on the continent get recycled with
  the mantle.

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Compaction

• The result of this pressure is a compaction of
  the sediment
• it is squeezed together causing a reduction in
  pore space and a sticking together of the grains.
  
• Under pressure, some chemical sediments, like
  halite, may recrystallize into a solid state.

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Cementation

• Most sediments are deposited in water containing
  dissolved minerals.
• The water flows through the sediment and some of
  these minerals precipitate on the grain surfaces.
  
• With time, this intergranular material
  effectively glues the sediment together into a
  cohesive solid- a sedimentary rock.

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Uplifting

• Because certain rocks are created under the
  Earths surface A process called uplifting occurs
  through orogeny and volcanic process, which then
  bring rocks to the surface. The rock is
  eventually becomes recycled again.

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Transportation

• This process occurs when the particles created by
  weathering are carried by ice, air, or water to a
  region of lower energy known as a sedimentary
  basin.

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Decomposition

• Decomposition takes place when a lowering of
  hydraulic energy, organic biochemical activity,
  or chemical changes occur.

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Crystallization

• When hot conditions that caused magma to melt
  will cool, either because the source of heat
  subsides or the magma moves into cooler regions
  of the Earth.
• When it gets cool enough the minerals that will
  make up the rock begin to crystallize and form an
  intergrown mass of crystals.
• If the crystals begin to form deep in the Earth
  where it is relatively warm the magma cools
  slowly allowing the crystals to grow relatively
  large.
• If the magma reaches the surface, the lava cools
  quickly and the crystals do not have time to grow
  very large.
• If the crystals cannot grow at all and volcanic
  glass is formed.

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Crystallization
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Earthquakes

• An earthquake is the shaking of the Earths
  surface caused by the rapid movement of the
  Earths rocky outer layer.
• Earthquakes occur when energy stored within the
  Earth, usually in the form of strain in rocks,
  suddenly releases.
• This energy is transmitted to the surface of the
  Earth by earthquake waves or seismic tremors.
• Most earthquakes are caused by the sudden slip
  along geologic faults because of movement of the
  Earths tectonic plates.

• The rocky tectonic plates move very slowly,
  floating on top of a weaker rocky layer.
• As the plates collide with each other or slide
  past each other, pressure builds up within the
  rocky crust.
• Earthquakes occur when pressure within the crust
  increases slowly over hundreds of years and
  finally exceeds the strength of the rocks.

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Plates

• The Earth is made up of plates.
• There are 2 kinds of plates
• (1) Continental Plate
• (2) Oceanic Plate
• These plates move past each other and
  occasionally slip above or below one another.
• As the plate sinks lower and lower beneath
  another plate, the heat and pressure it gives off
  causes the rock to melt. ? volcano
• Sometimes if one plate doesnt slide underneath
  another, the the plates will collide and push
  each other upward. ? mountains
• When this happens, they melt and recrystallize
  due to the heat and pressure put on them.

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Continental Plate

• Continental crust is much older, thicker and less
  dense than oceanic crust.
• The thinnest continental crust, between plates
  that are moving apart, is about 15 km (about 9
  mi) thick.
• In other places, such as mountain ranges, the
  crust may be as much as 75 km (47 mi) thick.
• Near the surface, it is composed of rocks that
  are felsic (made up of minerals including
  feldspar and silica).
• Deeper in the continental crust, the composition
  is mafic (made of magnesium, iron, and other
  minerals).

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Oceanic Plate

• Oceanic crust makes up 60 percent of the earths
  solid surface.
• Oceanic crust is thin and dense. Oceanic crust
  averages between 5 and 10 km (between 3 and 6 mi)
  thick.
• It is composed of a top layer of sediment, a
  middle layer of rock called basalt, and a bottom
  layer of rock called gabbro.
• Basalt and gabbro are dark-colored igneous, or
  volcanic, rocks.
• It is constantly produced at the bottom of the
  oceans in places called mid-ocean ridgesundersea
  volcanic mountain chains formed at plate
  boundaries where there is a build-up of ocean
  crust.
• This production of crust does not increase the
  physical size of the earth, so the material
  produced at mid-ocean ridges must be recycled, or
  consumed, somewhere else.
• Oceanic crust is continually recycled so that its
  age is not greater than 200 million years.

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• Plate collision where the oceanic plate (crust)
  will slide beneath the continental plate (crust)
  because it is more dense than the continental
  plate.

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• A plate collision where the continental plates
  (crusts) collide. Thus, they have to go up.

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Bibliography
The Rock Cycle. www.science.ubc.com.ca. 8 Aug.
1997. The University of British Columbia. 19 Sep.
2003 http//www.science.ca/geo/202/rock_cycle/roc
kcycle.htm/ The Rock Cycle. www.rocksandmineral
s.com. 21 Feb. 2003. SciLinks. 19 Sep. 2003.
http//www.rocksandminerals.com/rockcycle.htm. W
hats A Rock Cycle? www.priweb.org.
Paleontological Research Institution. 19 Sep.
2003. http//www.priweb.org/ed/pgws/geology/geolog
y1.html. Plate Tectonics. www.encarta.msn.com.
1993-2003. Encyclopedia Article from Encarta. 19
Spe. 2003 http//encarta.msn.com/encnet/refpages/R
efArticle.aspx?refid761554623pn1para29p29.
The Rock Cycle http//www.shore.ctc.edu/geology/
ProcessesProducts.html 19 Sep. 2003
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Credits
La Canada High School AP Environmental
SciencePD. 5/ Ewoldsen Sarah Dowling Rupa
Kamboj Joy Kim Tony Tavlian Jean Young