Prentice Hall EARTH SCIENCE

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Prentice Hall EARTH SCIENCE

• Tarbuck Lutgens

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Chapter 3 Rocks!
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Ch. 3.1 Rock Cycle Verbal Notes

• Whats the difference between Rocks and Minerals
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• Rocks are a combination of minerals!
• Rocks also contain clues about the environments
  in which they were formed, therefore the
  information obtained from rocks is essential to
  understanding the Earth.

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? Rocks are any solid mass of mineral or
mineral-like matter occurring naturally as part
of our planet.
? There are three types of rocks.

• IGNEOUS
• SEDIMENTARY
• METAMORPHIC

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The Three Types of Rocks
1. Igneous rocks are formed by the
crystallization of molten magma.
2. Sedimentary rocks are formed from the
weathered products of preexisting rocks that have
been transported, deposited, compacted, and
cemented.
3. Metamorphic rocks are formed by the alteration
of pre-existing rock deep within Earth (but still
in the solid state) by heat, pressure, and/or
chemically active fluids.
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• Interactions among the Earths water, air, land,
  and living things can cause rocks to change from
  one type to another.
• This continual process of change is called
• The Rock Cycle shows the interrelationships among
  the three rock types Igneous, Sedimentary,
  Metamorphic

The Rock Cycle
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• Igneous rocks are created
• 1. When magma cools and hardens beneath the
  surface.
• Magma is molten material that forms deep beneath
  the Earths surface.

• 2. When lava is erupted onto the surface from
  volcanic activity.
• Lava is magma that reaches the surface.

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What happens when a rock formed deep within the
Earth is brought to the surface ?
Sedimentary Rocks are formed through several
processes

• Weathering is a process in which rocks are broken
  down by water, air, and living things either
  physically or chemically.
• Sediments are weathered pieces of rocks that are
  often moved by water, gravity, glaciers, or wind.

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Sedimentary Rocks are formed through several
processes

• Eventually, sediments are compacted and
  cemented to form sedimentary rock.
• Compaction is the process in which sediments are
  squeezed together from weight to form rocks.
• Cementation is the process in which dissolved
  minerals form a cement that is deposited
  among sediments holding them together.

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Rocks buried deep in the Earth can become
Metamorphic Rocks

• Under extreme temperature and pressure rock will
  change into metamorphic rock.
• Metamorphic rock often melts due to increased
  pressure and/or temperature and becomes magma,
  which starts the cycle over by crystallizing and
  forming igneous rock.

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Where does the energy that drives the Earths
rock cycle come from?
? Processes driven by heat from the Earths
interior are responsible for forming both igneous
rock and metamorphic rock.
? Weathering and the movement of weathered
materials are external processes powered by
energy from the sun.
? External processes also produce sedimentary
rocks.
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Paths in the Rock Cycle

• The purple arrows show only one way in which rock
  may form and change.
• The blue arrows show some of the alternate paths
  that rocks take as they go through the rock cycle.

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The Rock Cycle