Download Name: Date: Earth Science Ms. Whittaker Igneous Rocks

Name: _____________________________________________
Earth Science
Date: ______________
Ms. Whittaker
Igneous Rocks- Note Outline
A. Formation:
1. Igneous rocks form from the _________________________________________ of magma
(_______________________________).
2. Magma is a mixture of liquid __________________________________________________.
3. Magma is less dense than the surrounding rocks, and will therefore
__________________________________________.
B. Types of Igneous Rocks
1. The cooling rate of magma differs causing
__________________________________________________________________________.
a. Intrusive Igneous Rocks

Forms by the ________________________________ underground
- “IN”-trusive / “IN” the ground
- Also known as plutonic

Because underground cooling is _________________________:
-
Rock crystals are ______________________ and have a
________________________ texture
b. Extrusive Igneous Rocks

Fast cooling of _______________ (________________ that has reached earth’s
surface)
-Because the lava ______________________________ (exposed to colder air),
rock crystals are ______________________ and rocks have a
____________________________________ texture
-Pumice is an Extrusive Igneous Rock that is VESICULAR (has gas pockets).
Because pumice formed so quickly, the rock formed around the pockets of gas,
creating “holes” in the rock. This allows the rock to float in water because of its
lower density
Picture: Cooling Time vs. Size of Crystals
KEY IDEA!
- The ______________________ of the igneous rock is determined by the
_____________________________________________________ of the
mineral crystals NOT if it is
________________________________________.
-
Rock texture is by ______________________________, not by
_____________________.
Types of Magma
Felsic Magma
Contains high amounts of
Ex.:
Mafic Magma
Contains high amounts of
Ex.:
The “Bells and Whistles” for Identifying an Igneous Rock:
1. Obvious crystals in a ______________________________________________.
2. ____________________________ texture
3. _____________________________________
If you see these characteristics, you are most likely looking at an igneous rock