Title: Rocks and The Rock Cycle
1Rocks and The Rock Cycle
2Igneous 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.
4Course-Grained Igneous Texture
5Fine-Grained Igneous Texture
6Obsidian Exhibits a Glassy Texture.
7Basalt
8Igneous Rocks
The term "igneous" comes from the Latin word
meaning "fire."
9Igneous Rocks
- Continental Crust Mostly Granite and Andesite
- Oceanic Crust Mostly Basalt
- Pillow Basalt - common in ocean
- Composition depends on rate of cooling
10Igneous Rocks
Minerals of Granite
Granite is an intrusive igneous rock
GRANITE
11Igneous Rocks
12Igneous 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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15Igneous Rocks
Batholith
16Igneous Rocks
- Extrusive Rocks - form at Earths surface
- Examples
- Obsidian
- Pumice
- Scoria
17Igneous Rocks
Extrusive Rock
18Igneous Rocks
Granite at Yosemite
How are they formed?
19Igneous Rocks
203.3 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.
213.3 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.
223.3 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
23Shale with Plant Fossils
243.3 Sedimentary Rocks
? Two Main Groups
2. Chemical sedimentary rocks form when dissolved
substances precipitate, or separate, from water.
- limestonemost abundant chemical rock
- microcrystalline quartz known as chert, flint,
jasper, or agate
- evaporites such as rock salt or gypsum
- coal
25Fossiliferous Limestone
26Sedimentary Rocks
- Remains of pre-existing rocks
- Usually forms layers
- Results from weathering and erosion
- May be mechanical or chemical
27Sedimentary Rocks
EXAMPLES
28Sedimentary 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
29Sedimentary Rocks
Conglomerate
Breccia
SANDSTONE
shale
Classification based on particle size
Clastic - particles cemented or compacted together
30Sedimentary Rocks
Limestone Formation
Forms from the buildup of Calcium Carbonate
Shells of once living sea organisms.
31Sedimentary Rocks
The Mississippi Delta is a large area of
sedimentary debris which has been carried from
North America.
32Sedimentary Rocks
Cave stalactites and stalagmites form when
minerals in water make deposits.
How are they formed?
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37Part II
383.4 Metamorphic Rocks
? Heat
- Provides the energy needed to drive chemical
reactions
? Pressure
- Causes a more compact rock with greater density
39Origin of Pressure in Metamorphism
40Metamorphic Rocks
- Rocks which have undergone change
- Result when sedimentary or igneous rocks
experience heat/pressure - Change - recrystallization or deformation
Marble
41Metamporhic Rocks
Expose the following to heat and
pressure potters clay limestone shale
And the following new rocks will
form ceramic marble slate
423.4 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
43Metamorphic Rocks
Layered texture - results from pressure on both
sides of rock - pressing components into layers
Foliated
Marble, Quartzite pressure insufficient to
foliate
Non-foliated
44Metamorphic Rocks
Foliated
slate
gneiss
45Metamorphic Rocks
Quartzite
Marble
Nonfoliated
How are they formed?
46Gneiss Typically Displays a Banded Appearance
47MarbleA Nonfoliated Metamorphic Rock
48The Rock Cycle
49Rock Cycle
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51The Rock Cycle
52Rock Cycle