The Rock Cycle

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The Rock Cycle
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What is the Rock Cycle?

• The idea that rocks are continually changing from
  one type of rock to another through Earths
  natural processes.

Are any of these rocks being created or destroyed
throughout the processes of the rock cycle?
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Key Words to Understanding the Rock Cycle

• Igneous Metamorphic Sedimentary
• Intrusive Extrusive Magma Lava
• Cooling Melting Crystallization (Crystal
  Size)
• Heat Pressure Weathering
  Erosion
• Sediment Compacting Cementing
  Deposition

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Igneous Rock
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Igneous Rock

• Igneous rock is formed when magma or lava cools
  and crystallizes
• INtrusive when magma cools INside
• cools slower larger crystals
• EXtrusive when lava cools OUTside
• cools faster smaller crystals

What is the difference between lava and magma?
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Metamorphic Rock
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Metamorphic Rock

• Metamorphic rock forms from heat pressure
• Metamorphic means to change form represents a
  chemical change
• Usually forms deep in Earths crust BUT it can
  form anywhere there is a lot of heat pressure

Where could these regions of heat or pressure
occur?
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Sedimentary Rock
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Sedimentary Rock

• Sedimentary rock is formed by layers of sediment
  being pressed together over time.
• Erosion and weathering near Earths surface
• Sediments are transported from one place to
  another deposited in layers with the oldest
  sediment on the bottom
• The layers become compacted and cemented together

What could these sediments be composed of?
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Extra Vocabulary Help

• Please read through the next slides if you need
  clarification on any of the vocabulary presented
  in this lesson!
• Slides 16-18 Igneous Vocab
• Slide 19 Metamorphic Vocab
• Slides 20-27 Sedimentary Vocab

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Melting Cooling

• Melting is the result of continued heating
• Leads to production of magma or lava and new
  igneous rocks which are formed when the the magma
  or lava cools.
• Cooling leads to the magma or lava forming a
  solid igneous rock.
• Magma is molten rock that is still inside of
  Earth
• Lava is molten rock that is on Earths surface

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Crystallization

• When the magma or lava 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.
• This is what causes intrusive or extrusive
  igneous rocks

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Crystallization
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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, but
  often the change occurs when the rock is still a
  solid!
• Pressure comes from the incredible weight of
  material surrounding the rock on all sides. Or,
  for example millions of years of sediment on top
  of each other.
• 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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Sediment

• Examples of sediment can be pretty much anything
  like
• Materials, originally suspended in a liquid,
  (usually water) that settles at the bottom of the
  liquid when it is left standing for a long time
  stream beds, mouth of rivers etc
• Material eroded from preexisting rocks that is
  transported by water, wind, or ice and deposited
  elsewhere
• Organic material such as fossil fragments,
  shells, seeds, bones etc.

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Sediment
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Weathering

• The process in which rocks are broken down by
  chemical and/or physical processes into smaller
  particles.
• There are three types of weathering
• Physical Weathering physical action which breaks
  up rocks. An example of this is freezing
  thawing of water trapped in the cracks or pores
  of rocks.
• 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, or mass wasting of
  exposed surfaces by natural forces such as wind,
  moving water and ice. Rock fall under gravity is
  also erosion.
• This is the removal process that follows
  weathering.

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Erosion
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Compaction

• The result of this pressure is a compaction of
  the sediment
• The sediment is squeezed or compacted together
  causing a reduction in pore space and a sticking
  together of the grains.
• The pressure is often a result of the layers of
  sediment on top pressing down on older layers.

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Cementation taking Compaction a step further

• 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, the liquid material effectively glues
  the sediment together into a cohesive solid - a
  sedimentary rock.

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Deposition Transportation

• The transportation process occurs when the
  particles created by weathering are carried or
  moved by ice, air, or water to a different
  location.
• The sediment is then deposited or laid to rest in
  that new location.