ROCKS

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ROCKS

• Rocks naturally formed, non-living masses of
  solid Earth material that are made up of
  minerals.
• There are three types of rocks
• 1) Sedimentary sediments
• 2) Metamorphic change in form
• 3) Igneous from fire (magma/lava)

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Sedimentary Rocks

• Form from the compaction and cementation of
  sediments
• Compaction means squeezing together of sediment
  layers
• Cementation means binding or gluing together of
  sediment particles
• Lithification is the formation of loose sediments
  into solid rock
• Sedimentary rocks form in horizontal layers and
  have horizontal sorting
• Sedimentary rocks usually contain fossils.

As sediments become deposited, compaction and
cementation occur because of the pressure pushing
down represented by the arrows.
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Types of Sediment Particles

• Clastic sediments rock/mineral fragments from
  weathered rocks (clay, silt, sand, pebbles,
  cobbles, boulders)
• Organic sediments particles produced by life
  activities of plants or animals.
• ex shells (clams), skeletons (limestone
  coquina), calcium carbonates. Peat plants that
  lived in swamps.
• Plant life ? peat ? soft coal ? hard coal ?
  diamonds
• 3) Chemical evaporites when ions (atoms with
  charges) join together, forming crystals that
  settle (precipitate) out of solution.
• ex halite and gypsum

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List of Sedimentary Rocks

• Conglomerate
• Sandstone
• Shale
• Breccia
• Rock Salt (halite)
• Gypsum
• Limestone
• Coal
• Dolostone

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Metamorphic Rocks

• Metamorphic means to change form
• Metamorphic rocks are formed when great heat and
  pressure are applied to existing rocks
  (sedimentary, metamorphic or igneous)
• The existing rock before metamorphism is called
  the parent rock.

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Types of Metamorphic Rocks

• Contact when molten material comes into contact
  with surrounding rocks.
• Regional Large areas associated with mountain
  building (orogeny). When deeply buried rocks are
  squeezed, movement of these layers will occur.
• EX The Adirondack mountains are formed by
  regional metamorphism.

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Characteristics of Metamorphic Rocks

• 1) Crystalline texture pressure can create
  large and small crystals to form. Pressure may
  cause large crystals to break into smaller ones.
  Most metamorphic rocks have crystalline texture.
• 2) Increased density grains are compressed
  closer to each other. Smaller volume, higher
  density.
• 3) Foliation and Banding
• a) Foliation crystals arranged in layers or
  bands in along which rocks are broken easily.
• b) Banding minerals of different densities
  recrystallize with great pressure and separate
  into layers.
• 4) Distortion of layers softened by heat and
  squeezed by pressure.

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List of Metamorphic Rocks

• Slate parent rock is shale
• Phyllite
• Schist
• Gneiss parent rock is granite
• Hornfels
• Quartzite parent rock is sandstone
• Marble parent rock is limestone

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Igneous Rocks

• Formed by recrystallization of molten rock
  material (magma)
• Igneous rocks contain crystal grains!
• 1) The crystal size is directly related to the
  cooling time.
• a) Slow Cooling large crystals, feels rough.
• b) Fast Cooling small crystals, feels
  smooth.
• c) Very Fast Cooling no crystals, looks and
  feels like glass.
• There are TWO MAJOR groups
• 1) Intrusive (from magma) cooled
  beneath/inside the surface
• 2) Extrusive (from lava) cooled at or near
  the surface.
• All igneous rocks are silicates (contain Si
  and O) but they vary in composition, color and
  density. They can be felsic (contain Al) or mafic
  (containFe).

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Igneous Rocks
Obsidian Pumice Rhyolite Andesite Basalt Granite Diorite Gabbro