Download Igneous Rocks - Mrs. GM Earth Science 300

Matt Cortright,
Claire Hilton,
Margot Sweeney,
Caylee Waters,
Tommy Watters
IGNEOUS ROCKS
What is the definition of an igneous rock?
 One that has crystallized from a molten material (magma).
What are some examples of igneous rocks?
 Granite can be used for architectural construction, ornamental stone, flooring,
paving, facing stones, worktops, gravestones and monuments. Pumice which can be
used as an abrasive material in hand soaps, soaps, cleansers, and dental products,
emery board, etc. Basalt is a commonly used in floor tiles and in construction
projects. The crushed form of this rock is used for concrete aggregate, asphalt
sidewalk aggregate, railroad ballast, and filter stone in drain fields.
IGNEOUS ROCKS
How common is an igneous rock?
 The most common igneous rock Basalt makes up most of the oceanic plates
and is founds at divergent plate boundaries. Felsic igneous rocks are most commonly
found along continental margins.
Where can they be found?
 An intrusive rock is one that has formed below the surface, and extrusive rock is
one that crystallized on Earth’s surface.
FORMATION
Where do they form?
 Extrusive – made when magma flows on the earth's surface.
 Intrusive - produced when magma solidifies deep beneath the earth.
How do they form?
 Extrusive rocks cool faster than intrusive. Some rocks are shot into the air and cool
pretty fast, others into waterways (also fast cooling).
 Some rocks however are underneath the crust so they cool more slowly.
What can affect their formation?
 Typically, the melting is caused by one or more of three processes that can all affect
their formation: an increase in temperature, a decrease in pressure, or a change in
composition.
FEATURES
Igneous features?
 Batholiths- The largest rock formations in the crust of the Earth. They consist of
granitic forms that cover tens of thousands of square kilometers and extend forward
for up to 60km.
 Sills-Structure produced by the flow of basaltic magma associated with a volcano.
Types of magma?
 Felsic- An igneous rock that is high in feldspar and silica. (e.g. Rhyolite and granite)
 Mafic- Magma or lava that is rich in iron and magnesium. (e.g. Basalt and Gabbro)
PLUTONS & VOLCANIC LANDORMS
http://www.indiana.edu/~geol105/images/gaia_chapter_5/dike&sill.jpg
FEATURES
What can they be changed into or from? How?
 Magma can be changed to igneous rocks by cooling under or above ground. Igneous
rocks can also be changed into metamorphic rock through heat and pressure. When
an igneous rock is weathered and eroded, it turns into sediments. Those sediments
can be compacted to make sedimentary rock. Igneous rocks can melt and cool to
form new igneous rocks.
Are there different types of igneous rocks?
 Igneous rock can be both intrusive and extrusive. Intrusive igneous rocks form within
Earth's crust. Extrusive igneous rocks form when the magma or molten rock pours
out onto the Earth's surface or erupts at Earth's surface from a volcano. If the rock
cools underground, it will take a longer time to cool due to the warmer temperatures,
whereas if it cools above ground, it will take less time to cool due to lower
temperatures. The slower the rocks cool, the bigger they will be.
ROCK CYCLE
http://www.cotf.edu/ete/images/modules/msese/earthsysflr/EFCycleP2.gif
CHARACTERISTICS
How are they classified?
 They are classified by texture, mineralogy, and chemistry. Whether they are extrusive
and Intrusive rocks or if they are fine grained/glassy or large grained.
What can they be used for?
 Igneous rocks can be used for flooring, landscaping, and construction
Projects. The most commonly used igneous rock is granite.
CHARACTERISTICS
What are characteristics of igneous rocks?
 Characteristics of igneous rocks include crystal shape and granularity. Grains range
from about 1mm to 2cm in size. The igneous rocks that formed inside the earth have
larger crystals because the cooling time is longer.
What is the composition of igneous rocks?
 Igneous rocks are mostly silicate minerals. But on rare occasions they can contain
carbon.
COMPARED TO OTHER ROCKS
Crystal size and cooling rate?
 Crystal size is effected by the cooling rate, slower the cooling rate, the greater the
size of the crystal
 When the magma cools rapidly it forms fine-grained rocks, these are called aphanite
igneous rocks
WORKS CITED
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<http://
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Evanstom: McDougal Littell, 2005. 121-126. Print.