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Rocks, Rocks, and More rocks!

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ROCKS, ROCKS, AND MORE ROCKS! Chapters 5 and 6 (Glencoe Earth Science) What is a rock? A rock is a hard substance made of one or more minerals There are 3 types of ... – PowerPoint PPT presentation

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Title: Rocks, Rocks, and More rocks!


1
Rocks, Rocks, and More rocks!
  • Chapters 5 and 6 (Glencoe Earth Science)

2
What is a rock?
  • A rock is a hard substance made of one or more
    minerals
  • There are 3 types of rocks
  • Igneous
  • Sedimentary
  • Metamorphic

3
Whats an Igneous Rock?
  • Formed by crystallization of magma
  • Igneous comes from the latin word for fire
  • These rocks are associated with fiery lava flows
  • Lava is magma that flows on the Earths surface

4
Types of Igneous Rocks
  • Extrusive
  • Formed from lava on Earths surface that cooled
    quickly
  • Known as volcanic rock
  • Fine-grained
  • Intrusive
  • Formed inside the Earth
  • Magma rises up into pre-existing rocks and
    hardens
  • Coarse-grained
  • Called Plutonic rocks after Pluto, the god of
    the Underworld
  • These rocks commonly produce landforms
  • Granite is most common

5
Igneous Rocks
  • Which is the intrusive rock?
  • Which is the extrusive rock?

6
What About Igneous Rocks?
  • Useful as building materials
  • Interlocking grainy texture provides strength
  • Resistant to weathering
  • Granite is especially durable
  • Used for columns, tiles and countertops, etc.
  • Valuable ore deposits are often associated with
    igneous rocks

7
Its Sedimentary, Watson!
  • Whats a sedimentary rock?
  • A rock formed from sediments
  • Sediments are pieces of material that have been
    carried/deposited by wind, water, etc.
  • Sedimentary rocks form when these pieces are
    cemented together

8
How do Sedimentary Rocks Form?
  • Weathering
  • Processes that break rock into smaller pieces
  • Chemical-minerals in rock are dissolved or
    chemically changed
  • Physical-minerals are unchanged rock fragments
    break off
  • Erosion
  • Movement of materials from one location to
    another
  • Caused by wind, moving water, gravity, glaciers
    (ice)
  • Eroded materials almost always moved downhill

9
Sediments, Classified
  • Clastic Rock
  • Refers to fragments of rock and minerals created
    by weathering and erosion
  • Clastic comes from the Greek word for broken
  • Classified by particle size

10
Deposition
  • Occurs when sediments are laid down on the ground
    or sink to the bottom of a body of water
  • When wind/water slows down, largest particles
    settle out first, etc. Smallest particles settle
    last.
  • Sediments moved by glaciers and landslides are
    not sorted.

11
Burial
  • Most sediments are deposited in basins
    (depressions)
  • As more sediments are deposited, the layers on
    the bottom are exposed to more heat and pressure.
  • Causes lithification
  • Physical and chemical processes that turn
    sediment into sedimentary rock

12
Process of Lithification
  • 1-Compaction
  • Weight of sediments forces them closer together
  • Water is squeezed out of mud
  • Sand resists compaction because of grain-to-grain
    contact

13
Process of Lithification
  • 2-Cementation
  • Temperatures increase
  • Buried sediments can be chemically changed
  • Mineral growth cements sediments together into
    solid rock
  • Two types of cementation
  • A new mineral grows between grains OR
  • The same mineral grows between or over grains

14
Features of Sedimentary Rock
  • Horizontal layering (bedding)
  • Graded bedding particle size becomes more
    coarse/heavy toward bottom layers
  • Cross-bedding formed as inclined layers of
    sediment move forward across a horizontal surface
  • Fossils
  • Evidence of once-living organisms

15
Types of Sedimentary Rock
  • Clastic Rock
  • Most common formed from deposits of loose
    sediments
  • 1/3 or more is pebble-called conglomerate
  • Not as common as rock w/ smaller pieces
  • If made with sandy grains-called sandstones
  • Very common
  • Particles smaller than sand-called shale

16
Types of Sedimentary Rock
  • Chemical Rocks
  • Formed when water evaporates leaving minerals
    behind
  • Ex Rock salt, some limestone
  • Stalactites, stalagmites
  • Organic Sedimentary Rocks
  • Formed from remains of a once-living thing
  • Ex coal

17
Why are Sedimentary Rocks Important?
  • Energy Resources
  • Coal, Oil, Natural gas are found in sedimentary
    rock
  • Many metals are mined from sedimentary rocks
  • Used in making cement (limestone)
  • Used in making blocks for walls (sandstone,
    limestone)

18
Metamorphic Rock
  • Changing one type of rock into another as a
    result of extreme heat, pressure, and/or chemical
    reactions
  • Can be formed from any of the three types of rock
  • The new rocks have different properties than
    the rock did before the morph

19
The Rock Cycle
  • Continuous changing and remaking of rocks
  • Rocks are constantly being recycled from one type
    to another

20
Example of the Path of a Rock Through the Rock
Cycle
  • Granite (igneous rock)
  • Wind/rain erodes exposed rock, bits flake off,
    carried to bottom of stream ? carried to river,
    along with other sediments ? carried to sea,
    deposited
  • Deposits build up ? form sandstone (sedimentary
    rock)?
  • Sediments continue to be buried and are under
    more pressure/higher temps ? pressed together
    even more ? form quartzite (metamorphic rock)?AND
    THE CYCLE CONTINUES
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