21.3 Rocks and the Rock Cycle - PowerPoint PPT Presentation

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21.3 Rocks and the Rock Cycle

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21.3 Rocks and the Rock Cycle Rocks are classified into three major groups based on how they formed Igneous Rocks Can be divided into two categories based on where ... – PowerPoint PPT presentation

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Title: 21.3 Rocks and the Rock Cycle


1
21.3 Rocks and the Rock Cycle
  • Rocks are classified into three major groups
    based on how they formed
  • Igneous Rocks
  • Can be divided into two categories based on where
    they form

2
  • A. Intrusive Rocks igneous rocks that form
    underground from magma
  • Cool slowly allowing crystals to grow large
    giving it a coarse-grain texture

3
  • B. Extrusive Rocks igneous rocks that form at
    the surface from lava
  • Cool quickly resulting in the crystals to be
    small giving it a fine grain texture

4
Igneous Rock Textures

5
  • II. Sedimentary Rock rock that forms over time
    as sediment is squeezed and cemented together
  • Sediment small, solid pieces of material that
    comes from rocks or living organisms
  • Sediment is deposited in layers by running water
    or wind
  • Sediment is cemented together by pressure from
    overlying layers
  • Three Main Groups of Sedimentary Rocks
  • 1. Clastic
  • 2. Chemical
  • 3. Organic

6
  • Clastic Rock sedimentary rocks that form from
    the broken fragments of other rocks
  • Clastic Rocks are classified based on the size of
    their fragments
  • Example Conglomerate rock fragments that
    consist of gravel and pebbles

7
  • Some clastic rocks are made of smaller particles
    (sandstone)

8
  • 2. Chemical Rocks rocks that form when
    minerals precipitate out of solution
  • Example when ocean water evaporates (halite)

9
  • Organic Rocks rocks that form as a result
    of organic processes
  • Shells of marine animals like corals, clams,
    mussels sink to the ocean floor when they die.
  • Example Limestone and calcite (chalk)



10
  • III. Metamorphic Rocks rock that have been
    changed by temperature, pressure, or chemical
    reactions.
  • Most metamorphic rocks form under high
    temperatures and pressures deep underground.
    (slate and schist shown below)


11
Metamorphic Rocks
  • Foliation a layering of minerals in a rock due
    to intense pressure squeezing the crystals
    together.

12
Metamorphic Rock pictures
  • Metamorphic Rocks like gneiss show banding of
    light and dark minerals.

13
Metamorphic Rocks and their Parent Rocks
  • Examples
  • Slate parent is shale
  • Gneiss parent is granite/schist
  • Quartzite parent is sandstone
  • Marble parent is limestone

14
IV. Rock Cycle
  • Rock Cycle series of processes in which rocks
    continuously change from one type to another.
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