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Rocks and The Rock Cycle

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Rocks and The Rock Cycle Agents of Metamorphism 3.4 Metamorphic Rocks Heat Pressure Provides the energy needed to drive chemical reactions Causes a more compact ... – PowerPoint PPT presentation

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Title: Rocks and The Rock Cycle


1
Rocks and The Rock Cycle
2
Igneous Rocks
  • Volcanic Rocks
  • Form when magma/lava cools
  • Intrusive rocks - form below Earth's surface
  • Extrusive rocks - form at Earth's surface
  • Compose 95 of Earth's crust

All rocks originally come from igneous rock.
3
Igneous Rocks
? Igneous rocks can be classified based on their
composition and texture.
1. Texture
Coarse-grained texture is caused by slow
cooling resulting in larger crystals.
Fine-grained texture is caused by rapid
cooling resulting in smaller, interconnected
mineral grains.
4
Course-Grained Igneous Texture
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Fine-Grained Igneous Texture
6
Obsidian Exhibits a Glassy Texture.
7
Basalt
8
Igneous Rocks
The term "igneous" comes from the Latin word
meaning "fire."
9
Igneous Rocks
  • Continental Crust Mostly Granite and Andesite
  • Oceanic Crust Mostly Basalt
  • Pillow Basalt - common in ocean
  • Composition depends on rate of cooling

10
Igneous Rocks
Minerals of Granite
Granite is an intrusive igneous rock
GRANITE
11
Igneous Rocks
12
Igneous Rocks
  • Plutons - large intrusive rock bodies
  • Dike - intrusion of magma up through existing
    rock (page 547)
  • Sill - intrusion of magma parallel to horizontal
    rock layers
  • Laccolith - mushroom shape (page 547)
  • Batholith - very large, many mountain range cores

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Igneous Rocks
Batholith
16
Igneous Rocks
  • Extrusive Rocks - form at Earths surface
  • Examples
  • Obsidian
  • Pumice
  • Scoria

17
Igneous Rocks
Extrusive Rock
18
Igneous Rocks
Granite at Yosemite
How are they formed?
19
Igneous Rocks
20
3.3 Sedimentary Rocks
? Weathering, Erosion, and Deposition
Erosion involves the weathering and the
removal of rock.
Deposition occurs when an agent of
erosionwater, wind, ice, or gravityloses energy
and drops sediments.
21
3.3 Sedimentary Rocks
? Compaction and Cementation
Compaction is a process that squeezes, or
compacts, sediments.
Cementation takes place when dissolved
minerals are deposited in the tiny spaces among
the sediments.
22
3.3 Sedimentary Rocks
? Two Main Groups
1. Clastic sedimentary rocks are composed of
weathered bits of rocks and minerals.
Classified by particle size
Common rocks include
- Shale (most abundant)
- Sandstone
- Conglomerate
23
Shale with Plant Fossils
24
3.3 Sedimentary Rocks
? Two Main Groups
2. Chemical sedimentary rocks form when dissolved
substances precipitate, or separate, from water.
  • Common rocks include

- limestonemost abundant chemical rock
- microcrystalline quartz known as chert, flint,
jasper, or agate
- evaporites such as rock salt or gypsum
- coal
25
Fossiliferous Limestone
26
Sedimentary Rocks
  • Remains of pre-existing rocks
  • Usually forms layers
  • Results from weathering and erosion
  • May be mechanical or chemical

27
Sedimentary Rocks
EXAMPLES
28
Sedimentary Rocks
  • Sediment may be clastic or chemical
  • Clastic sediment consists of particles - may be
    compacted or cemented together
  • Examples sandstone, shale, conglomerate
  • Chemical sediments form when minerals precipitate
    from water
  • Examples limestone, halite, dolomite

29
Sedimentary Rocks
Conglomerate
Breccia
SANDSTONE
shale
Classification based on particle size
Clastic - particles cemented or compacted together
30
Sedimentary Rocks
Limestone Formation
Forms from the buildup of Calcium Carbonate
Shells of once living sea organisms.
31
Sedimentary Rocks
The Mississippi Delta is a large area of
sedimentary debris which has been carried from
North America.
32
Sedimentary Rocks
Cave stalactites and stalagmites form when
minerals in water make deposits.
How are they formed?
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Part II
38
3.4 Metamorphic Rocks
? Heat
  • Provides the energy needed to drive chemical
    reactions

? Pressure
  • Causes a more compact rock with greater density

39
Origin of Pressure in Metamorphism
40
Metamorphic Rocks
  • Rocks which have undergone change
  • Result when sedimentary or igneous rocks
    experience heat/pressure
  • Change - recrystallization or deformation

Marble
41
Metamporhic Rocks
Expose the following to heat and
pressure potters clay limestone shale
And the following new rocks will
form ceramic marble slate
42
3.4 Metamorphic Rocks
? Two main categories
1. Foliated Metamorphic Rock
  • Has a banded or layered appearance

2. Nonfoliated Metamorphic Rock
  • Does not have a banded texture

43
Metamorphic Rocks
Layered texture - results from pressure on both
sides of rock - pressing components into layers
Foliated
Marble, Quartzite pressure insufficient to
foliate
Non-foliated
44
Metamorphic Rocks
Foliated
slate
gneiss
45
Metamorphic Rocks
Quartzite
Marble
Nonfoliated
How are they formed?
46
Gneiss Typically Displays a Banded Appearance
47
MarbleA Nonfoliated Metamorphic Rock
48
The Rock Cycle
49
Rock Cycle
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The Rock Cycle
52
Rock Cycle
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