Rocks and the Rock Cycle

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Rocks and the Rock Cycle
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ROCKS!

• Rocks are naturally formed solid that is
  usually made up of one or more types of minerals.
  
• They are divided into three groups based on how
  they form.

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• The 3 types are
• Igneous Rocks formed when molten rock cools and
  becomes solid.
• Made frommolten rock or magma
• Classified according to origin, texture, and
  mineral composition

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• Four textures
• Glassy
• Fine Grain
• Coarse Grain
• Porphyritichas large crystals scattered on a
  background of much smaller crystals
• 2 main categories of igneous rocks are
• Intrusiveforms when magma cools inside Earth
• Extrusiveforms when lava cools on Earth's
  surface

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Basalt Forming--Extrusive
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Textures

• Glassy
• Fine-grained

• Coarse-grained
• Porphyritic

Obsidian
Granite
Basalt
Granite
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• Extrusive- Formed from lava volcanic
• Intrusive- Formed deep within the earth

Obsidian
Pumice
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Uses of Igneous Rock

• Many igneous rocks are hard, dense, and durable
  These qualities make them very useful for tools
  and building materials.
• Granite is one of the most abundant igneous
  rocks and it has a long history of being used as
  a building material.
• Basalt is crushed to make gravel that is used in
  construction
• Pumice has a rough surface which makes it a good
  abrasive for cleaning and polishing.
• Perlite comes from obsidian and is often mixed
  with soil for starting vegetable seeds.

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• Sedimentary Rocks forms when pieces of older
  rocks, plants, and other loose material get
  pressed or cemented together.
• Made from--particles deposited by wind and water
  after being eroded from other rock.

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Lithification

• The process by which sediment becomes
  sedimentary rock.
• The four steps that make sedimentary rock.
• Erosion
• Deposition
• Compaction
• Cementation

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Erosion

• Occurs when water or wind loosens rock and soil
  and carries it away.
• Erosion is a destructive force.

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Deposition

• The process by which the sediment settles out of
  the water or air carrying it.
• Sediment is deposited when the wind or water
  slows down.
• After sediment has been deposited, the processes
  of compaction and cementation change the sediment
  into sedimentary rock.

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Compaction

• As the sediments settle they will loosely fit on
  top of each other.
• As the years go by, more and more sediment is
  added.
• The bottom layers get compacted by the weight of
  the layers above them.
• Compaction is the process that presses sediments
  together.

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• Classified into 3 categories according towhat
  they are made of.
• These categories are
• Clastic formed when rock fragments are squeezed
  together.
• Organic formed from the remains of living
  things.
• Chemical formed when dissolved minerals
  crystallize

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Common Clastic Sedimentary Rocks
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Organic Rocks
Fossiliferous Limestone

• Limestone

Coquina
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Coal

• Formed from the remains of ancient swamps.
• As layer upon layer of dead plants built up, the
  bottom layers were compacted into coal.
• Stored chemical energy from the sun.
• Fossil fuel.

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Chalk

• Formed from the shells of ancient sea life.

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Seven Sisters in Sussex
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Chemical Sedimentary Rocks
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Halite Forms large crystals
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Uses of Sedimentary Rock

• Sandstone and Limestone as building materials.
• Whitehouse in Washington D.C. is built of
  sandstone.
• Limestone has many industrial uses, including
  being used in smelting iron ore and making cement.

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• Metamorphic rocks rock that has changed from one
  form to another.
• Made when--heat or pressure causes older rocks to
  change into new types of rocks
• This is called a metamorphism.

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Metamorphic Rock Pictures
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• Divided into 2 basic groups based onthe
  arrangement of the grains
• These 2 groups are
• Foliatedthe thin layering found in many
  metamorphic rocks. These rocks will split along
  these bands.
• Nonfoliated--Mineral grains are randomized. Do
  not split into layers.

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Granite to Gneiss-foliated

• Granite becomes gneiss when subjected to heat
  and pressure.
• The atoms end up lining up in bands.
• Gneiss is foliated.

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Shale to Slate-foliated

• Slate is formed when shale is subjected to
  pressure.
• Slate is denser, more compacted than shale and
  the slate becomes foliated.
• Slate produces flat plates when broken.

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Slate to Schist-foliated

• If slate is subjected to even greater pressure
  and moderate temperatures, schist is formed.

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Quartzite-Nonfoliated

• Occurs when sandstone is compressed by pressure.
• It is formed when weakly cemented quartz
  particles in sandstone recrystallize.
• Usually very hard.

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Marble - Nonfoliated

• Formed from metamorphed limestone.
• Much harder and denser.

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Economic Importance of Minerals

• Minerals are in many things we see and use
  everyday such as bricks, glass, cement, plaster,
  iron, gold.
• Marble is extremely useful for building for
  these reasons
• It has a fine, even grain.
• It is relatively easy to cut into thin slabs.
• It can be polished easily.
• The Taj Mahal in Agra, India is made of gleaming
  white marble.

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Taj Mahal
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Coral Reefs

• Coral reefs are responsible for the creation of
  one of the 2 types of organic sedimentary rocks
  limestone.
• Limestone is produced from the hard shells of
  coral left behind when they die and become
  compressed and cemented together.
• Coral reefs only live in warm, clear, shallow
  tropical water
• Two locations they can be found in the U.S. are
• 1. Florida
• 2. Hawaii

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• There are 3 types of coral reefs
• 1. Fringing reef
• 2. Barrier reef
• 3. Atoll
• Limestone from coral can be found on continents
  in places where uplifting has raised ancient sea
  floors above sea level.

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Fringing Reef Polynesian island of Mooréa
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Barrier Reef The Great Barrier Reef in Australia
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Atoll Maldives in the Indian Ocean
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The Rock Cycle
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• The rock cycle is a series of processes on
  Earths surface and inside the planet that slowly
  change rocks from one kind to another.
• Earths constructive and destructive forces
  including plate tectonics move rocks through
  the rock cycle.
• The rock cycle can follow many different
  pathways.

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IGNEOUS
Crystallization
MAGMA
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Weathering
Volcanic IGNEOUS Plutonic
Crystallization
MAGMA
Uplift
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SEDIMENT
SEDIMENT
Weathering
Volcanic IGNEOUS Plutonic
Crystallization
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Volcanic IGNEOUS Plutonic
SEDIMENTARY
Crystallization
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Volcanic IGNEOUS Plutonic
SEDIMENTARY
Crystallization
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Volcanic IGNEOUS Plutonic
SEDIMENTARY
Increased PT
METAMORPHIC
Crystallization
Burial
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Volcanic IGNEOUS Plutonic
Can you see any shortcuts?
SEDIMENTARY
Increased PT
METAMORPHIC
Crystallization
Melting
Burial
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Volcanic IGNEOUS Plutonic
SEDIMENTARY
Increased PT
METAMORPHIC
Crystallization
Melting
Burial
MAGMA
Uplift
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The Rock Cycle

• The diagram of the rock cycle shows how the
  earth's rocks are changed again and again

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Distribution of Rocks in the U.S.
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