Rocks

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Rocks

• 8th grade Earth Science

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Classifying Rocks

• Mineral Composition rocks are made of mixtures
  of minerals and other materials. Some contain a
  single mineral. Others contain several minerals.
• Color color provides clues to the rocks
  mineral composition.
• (Ex granite light basalt dark)
• Texture the look and feel of the rocks
  surface.
• They use shape, size and pattern.
• Origin how the rock is formed.

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3 Types of Rocks

• There are 3 major groups of rocks
• Igneous
• Sedimentary
• Metamorphic

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Igneous Rocks

• The name igneous comes from a Latin word meaning
  fire.
• Igneous rocks can be either intrusive or
  extrusive rock.
• Extrusive formed from lava that erupted onto
  the Earths surface.
• Basalt is the most common extrusive rock.
• Intrusive formed from magma that hardens
  beneath the Earths surface.
• Granite is the most common intrusive rock.

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Igneous Rocks

• Obsidian
• extrusive
• Granite
• intrusive

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Sedimentary Rocks

• Sedimentary rocks are formed through a series of
  processes
• Erosion
• Deposition
• Compaction
• Cementation

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Sedimentary Rocks

• Erosion water, wind or ice loosen and carry
  away fragments of rock.
• Deposition sediment settles out of the water or
  wind carrying it.
• Compaction process that presses the sediments
  together.
• Cementation dissolved minerals crystallize and
  glue particles of sediment together.

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Types of Sedimentary Rocks

• There are 3 major groups of sedimentary rocks
• Clastic forms when rock fragments are squeezed
  together.
• Organic remains of plants or animals are
  deposited in thick layers.
• Chemical when minerals that are dissolved in a
  solution crystallize.

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Sedimentary Rocks

• Clastic
• sandstone
• Organic
• coal
• Chemical
• limestone

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Metamorphic Rocks

• Heat and pressure deep beneath Earths surface
  can change any rock into metamorphic rock.
• Geologists classify metamorphic rocks according
  to the arrangement of the grains that make up the
  rocks.

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Metamorphic Rocks

• There are 2 classifications for metamorphic
  rocks
• Foliated have their grains arranged in parallel
  layers or bands.
• Nonfoliated mineral grains are arranged
  randomly. They do not split into layers.

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Metamorphic Rocks

• Foliated
• gneiss
• Nonfoliated
• quartzite

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The Rock Cycle

• The rock cycle is the series of processes on
  Earths surface and in the crust and mantle that
  slowly change rocks from one kind to another.

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