Download Igneous Rocks: Notes Outline

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Section _________
Igneous Rocks: Notes Outline
Holt Science & Technology Earth Science, Chapter 4: Section 3
I.
Igneous Rocks –
- What do igneous rocks come from?
-
What is a melting point?
§
Magma “_________________” between _____________ and __________
§
The ________________________ of magma is ALSO between _____________ and
_____________
§
That means, ____________________________BECOME a solid and _________________
___________________________ BECOME a liquid.
II.
Three Ways that Magma Can Form:
1. A Decrease in Pressure -
2. An Increase in Temperature –
3. A Change in Composition –
Igneous Rocks: Notes Outline (continued)
III.
Texture
§
How is the texture of igneous rocks is a direct result of the rate at which the magma they were
formed from cooled?
§
Explain what happens to the mineral crystals in igneous rocks if the magma they came from
cooled slowly.
§
Describe what happens to the mineral crystals in igneous rocks if the magma they came from
cooled quickly.
A. Intrusive Igneous Rock –
-
Describe the rate at which intrusive igneous rocks cool and the texture they have:
B. Extrusive Igneous Rock –
-
IV.
Describe the rate at which extrusive igneous rocks cool and the texture they have:
Three Ways that Igneous Rocks Can Form FROM Magma:
(For each method listed, describe the rate at which the magma would cool and the resulting
texture of the igneous rocks formed)
1. “Spew” out of a volcano –
2. “Ooze” out of a volcano –
3. Get trapped somewhere on the way up to the surface -
Igneous Rocks: Notes Outline (continued)
V.
VI.
Deciphering Earth’s History with Igneous Rocks
(Describe how each of the three bullet points affects geologists ability to decipher Earth’s
History)
-
The ocean floor is MADE from lava flows.
-
Pre-existing landforms are often buried by lava flows.
-
Geologists can identify rock that was formed from lava flows.
Homework
1. Draw a picture of a volcano in the space below. Color it.
2. Label on the picture magma from which a fine-grained extrusive igneous rock will be formed.
3. Label on the picture magma from which a course-grained intrusive igneous rock will be
formed.
4. Label on the picture magma from which a medium grained igneous rock might be formed.