Download Cooling Melting Heat and Pressure Weathering and Erosion Heat

Earth Science Notes
Chapter Four-Rocks: Mineral Mixtures
NAME:__________________________
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SECTION 1-Understanding Rock [Petrology]
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1.
2. Classified into three main types-igneous, sedimentary, and metamorphic-depending on how they formed.
3. The rock cycle is a series of natural processes by which rocks are slowly changed from one kind of rock to
another kind of rock. Rocks change slowly both inside the Earth and at the Earth’s surface.
4. Rock Cycle Diagram:
Melting
Weathering and
Erosion
Cooling
Heat and
Pressure
Melting
Weathering
and Erosion
Weathering
and Erosion
Compaction
and
cementation
Heat and Pressure
5. Rocks changed by the following natural processes:
a. Weatheringb. Erosionc. Compaction-a process that occurs when layers of sediment become compressed by the weight of
layers above them.
d. Cementatione. Melting and cooling.
6. Classification of Rocks: (two ways)
a. CompositionExample-the igneous rock granite is made up of the minerals mica, feldspar, and quartz.
b. Texture-the sizes, shapes, and positions of the grains that a rock is made of.
1. Fine-grained2. Coarse-grained-rocks that are made of large grains, such as pebbles. Ex. conglomerate
3. Medium-grainedPage 1
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SECTION 2-Igneous Rock [rock from “fire”]
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1. Igneous rock is formed from hot, molten liquid materials that cool and harden.
a. Magma1. Felsic magma-magma with a high silica content [silicon and oxygen]; it is light colored, thick,
and pasty.
2. Mafic magmab. Lava-molten rock on the Earth’s surface.
3. Magma cools into various types of igneous rock depending on the (1)composition of the magma and (2)the
amount of time it takes the magma to cool and solidify .
4. Two groups of igneous rocks: [Figure 11 page 88]
a. Intrusive1. cooled slowly.
2.
3. have a coarse texture.
b. Extrusive-formed when lava cools on the Earth’s surface. All extrusive rocks...
1.
2.
3.
5. Further classification of Igneous Rocks:
a. Can further classify igneous rocks by the type of magma they formed from.
b. Three types of Igneous Rocks:
1. Basaltic-
a. Hawaii-lava is basaltic in nature. Eruptions on these islands are calm.
2. Granitic-form from felsic magma; thick magma that does not flow easily due to high silica
content. [temp. is below 800oC]. Contains high percent of aluminum, potassium, and sodium, thus
rocks are less dense and light colored.
a. Usually associated with violent volcanic eruptions.
3. Andesitic-
*SEE ROCK TYPE STUDY GUIDE on Igneous Rocks
BASALTI C
ANDESITI C
GRA NITI C
INTR USIV E
Gabbro
Diorite
Granite
EXT RUSI VE
Basalt and Scoria
Andesite
Rhyolite, Obsidian, & Pumice
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SECTION 3-Sedimentary Rock [75% of rocks at Earth’s surface]
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1. Rocks that are produced by weathering-breaking down of rock material into small fragments called
sediments, either mechanically or chemically.
2.
3. Classification of Sedimentary Rock:
* SEE ROCK TYPE STUDY GUIDE on Sedimentary Rocks
a. Three classes of sedimentary rock:
1. Clastic (detrital)Sedimentary Rock2. Chemical Sedimentary Rock-come out of solution or are left behind by evaporation. Chemical
sed. rocks generally have a non-granular texture.
3. Organic Sedimentary Rock------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SECTION 4-Metamorphic Rock [rock that has changed shape, texture, or composition]
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1. Metamorphic Rocks2. Occur at depths of 12-16 km (7-10 miles) below surface where heat and pressure aren’t quite enough to get
the rocks to melt. [If it melts you have magma which cools to form igneous rocks!]
a. Three changes may occur to a rock that undergoes metamorphism:
1.
2. Enlargement of crystals.
3.
3. Two types of metamorphism:
1. Contact Metamorphism-”baking”—
2. Regional Metamorphism-occurs over an area thousands of square kilometers during periods of
tectonic activity (mountain building).
a. The movement of tectonic plates against each other creates tremendous heat and pressure.
This heat and pressure causes chemical changes in the minerals of the rocks.
b.
4. Classification of Metamorphic Rocks done by their textures:
* SEE ROCK TYPE STUDY GUIDE on Metamorphic Rocks
a. Foliated Metamorphic Rocks:
1.
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b. Nonfoliated Metamorphic Rocks:
1.
2. Usually only contain one mineral.
3.
CHAPTER 4 QUESTIONS TO CONSIDER:
1. Distinguish between a rock and a mineral.
2. Describe how each type of rock changes into another as it moves through the rock cycle.
3. List two characteristics of rock that are used to help classify it.
4. Explain how the cooling rate of magma affects the properties of igneous rock.
5. Distinguish between igneous rock that cools deep within the crust and igneous rock that cools at the surface.
What do petrologist call each igneous rock type?
6. Contrast basaltic, granitic, and andesitic igneous rocks.
7. Explain how sedimentary rocks form from sediments.
8. Describe the process by which clastic sedimentary rock forms. How are sandstone and siltstone different
from one another? How are they the same?
9. Describe two ways that a rock can undergo metamorphism.
10. Describe the difference between foliated and nonfoliated metamorphic rock.
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