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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 – PowerPoint PPT presentation

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Title: ROCKS

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

Sedimentary Rocks
  • Form from the compaction and cementation of
  • Compaction means squeezing together of sediment
  • 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.
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 ?
  • 3) Chemical evaporites when ions (atoms with
    charges) join together, forming crystals that
    settle (precipitate) out of solution.
  • ex halite and gypsum

List of Sedimentary Rocks
  • Conglomerate
  • Sandstone
  • Shale
  • Breccia
  • Rock Salt (halite)
  • Gypsum
  • Limestone
  • Coal
  • Dolostone

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.

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.

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
  • 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.

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

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
  • 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

Igneous Rocks
Obsidian Pumice Rhyolite Andesite Basalt Granite Diorite Gabbro
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