chapter 6, section 2
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CHAPTER 6, SECTION 2Standards 3c. Students know how to explain the
properties of rocks based on the physical and chemical conditions in which they are formed, including plate tectonic properties.
Objective 1 Summarize 3 factors that affect whether rock melts.
Objective 2 Describe how the cooling rate of magma and lava affects the texture of igneous rocks.
Objective 3 Classify igneous rocks according to their composition and texture.
Objective 4 Describe intrusive and extrusive igneous rock structures.
Assessment End of Section Questions, Daily Quiz, Chapter Test
Review Daily Bellwork, Science Starters, Standards Practice
KEY TERMS
Create a flash card for the following key terms (p. 129 in textbook):
Igneous RockIntrusive Igneous RockExtrusive Igneous RockFelsicMafic
If you finish early, study your flash cards!
IGNEOUS ROCKMost Igneous Rock (formed from cooled magma) is crystalline (made of crystals).
Magma forms when rocks melt.
3 Factors determine when rock melts: temperature, pressure, and pressure of fluids in the rock.
IGNEOUS ROCK VIDEO CLIP
PARTIAL MELTING Different minerals have different melting
points. Minerals with lower melting points, melt first. The process of different minerals in the rock
melting at different temperatures is called PARTIAL MELTING.
FRACTIONAL CRYSTALLIZATION
When magma cools, the opposite of partial melting occurs: freezing.
Different minerals have different freezing points.
As some minerals freeze, the composition of the remaining magma changes, creating new minerals.
This is called fractional crystallization.
FRACTIONAL CRYSTALLIZATION
Crystals that freeze/form early tend to be the largest.
TYPES OF IGNEOUS ROCK• Magma that
cools deep inside the crust
Intrusive
• Lava that cools at the Earth’s surface
Extrusive
INTERACTIVE! Create and Acrostic Poem using the word
IGNEOUS. I G N E O U S
TEXTURES OF IGNEOUS ROCKSCoarse-Grained
• Intrusive• Large, well-
developed mineral crystals
• Ex.: Granite
Fine-Grained• Extrusive• Small Mineral
Grains• Grains cannot be
seen with human eye
• Ex: Basalt
Other• Mixture of large and
small crystals• Forms as a result of
slow cooling at first then rapid cooling.
• Highly viscous magma that cools quickly results in very few crystals• If this magma has
little gas=GLASSY• If this magma has
lots of gases=VESICULAR (holes)
TEXTURES VIDEO CLIP
QUICK CHECK!!1. Name the 2 types of Igneous Rock:
____________________________________________2. Give an example of a Course-Grained Igneous
Rock: ______________________________________
COMPOSITION OF IGNEOUS ROCKSMineral Composition of igneous
rocks is determined by the chemical composition of the magma from which the rock formed.
Three families of igneous rock:FelsicMaficIntermediate
COMPOSITION FAMILIESFe
lsic
Roc
k • Forms from Magma that has large amount of Silica.
• Light coloring
• Contains feldspar
Mafi
c Ro
ck
• Forms from Magma that has low amounts of silica and lots of iron and magnesium
• Dark in color
Inte
rmed
iate
Ro
ck
• Contains less silica than Felsic but more than Mafic
INTRUSIVE ROCK STRUCTURES Igneous Rock masses that form underground are called
INTRUSIONS. 5 types of intrusions:
Batholiths—largest of all intrusions, larger than 100 km squared, form the core of mountains
Stocks—same as a batholith but smaller than 100 square km.
Laccoliths— “lake of rock”, when magma flows between rock layers and spreads upward into a dome shape.
Sills-when magma flows between the layers of rock and hardens. Always parallel to the layers of rock below and above.
Dike-Magma that forces itself through vertical fractures and solidifies.
EXTRUSIVE ROCK STRUCTURESIgneous rock masses that form on Earth’s surface are called EXTRUSIVE ROCK STRUCTURES.
Lava from a volcano that cools and becomes rock is an EXTRUSIVE ROCK STRUCTURE.
ANIMATED INTRUSIVE AND EXTRUSIVE FEATURES
QUICK CHECK!!1. What is the difference between Intrusive and
Extrusive Rock Structures? __________________________________________________________________________________________________________________________________________
2. What is Felsic Rock? ____________________________________________________________________________________________
3. Name and Define 2 types of Intrusive Rock Structures: ________________________________________________________________________________________________________________________________________________________________________________________
ASSESSMENT In groups create posters for one of the
following: Intrusive Extrusive Course-Grained Fine-Grained Felsic Mafic Intermediate
DAILY QUIZ
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