Elevated Landforms
Castle Rock, CO
Shiprock NM
Mt. Cotopaxi Ecuador
Pikes Peak CO
Igneous Rocks
If you can’t take the heat, stay out of the kitchen.
H. S Truman
Igneous Rocks
• Formed from cooled magma (melted rock)
Inner core
Outer core
Mantle
Crust
Mantle and outer core are melted
Igneous Rocks
• Parts of the crust can be melted
Igneous Rocks
• (Notice the ocean floor?)
The most common type of igneous rock—basalt!
Igneous Rocks
• Magma on the surface is called lava
Igneous Rocks
• We will study the motion of these lithospheric plates in the next unit
Igneous Rocks
• (Notice the difference in the crust?)
• The slower it cools, the larger the crystals grow
• Intrusive— cools inside the crust
• Extrusive— cools outside the crust
Igneous Rocks
• The slower it cools, the larger the crystals grow
• Intrusive— cools inside the crust
--cools slowly
• Extrusive— cools outside the crust
--cools fast
Igneous Rocks
• The slower it cools, the larger the crystals grow
• Intrusive— cools inside the crust
--cools slowly —large crystals
• Extrusive— cools outside the crust
--cools fast —small crystals
Igneous Rocks
• The slower it cools, the larger the crystals grow
• Intrusive— cools inside the crust
--cools slowly —large crystals--rough
• Extrusive— cools outside the crust
--cools fast —small crystals--smoother
Igneous Rocks
Igneous Rocks
• Q: What about a rock that cools slowly for a while, then gets exposed so it cools quickly at the end?
Igneous Rocks
• Q: What about a rock that cools slowly for a while, then gets exposed so it cools quickly at the end?
• A: You get large
crystals in a fine
gray background
• Vary in color due to the differences in the mineral content of the magma
Light Minerals Dark Minerals
Quartz Amphibole
Potassium Feldspar Biotite mica
Muscovite mica Pyroxene
Olivine
Igneous Rocks
• Magma varies depending on where it’s found
Ocean Floor Continental
darker color lighter color
denser lighter (less dense)
thinner fluid thicker fluid
less gas bubbles more gas bubbles
Igneous Rocks
• Magma varies depending on where it’s found
Ocean Floor Continental
darker color lighter color
denser lighter (less dense)
thinner fluid thicker fluid
less gas bubbles more gas bubbles
Igneous Rocks
More gas bubbles makes a more violent volcanic eruption!
• Classified by color and texture
• See Table on pU20
Igneous Rocks
• Classified by color and texture
• See Table on pU20
Igneous Rocks
• Types: (By color and texture)
Light and Coarse—pegmatite (and granite)
Light and Medium—Granite
Light and Fine—rhyolite
Continental Igneous Rocks
• Types: (By color and texture)
Medium and Coarse—pegmatite (and diorite)
Medium and Medium—Diorite
Medium and Fine—Andesite (and basalt)
Intermediate Igneous Rocks
• Types: (By color and texture)
Dark and Coarse—pegmatite (and gabbro)
Dark and Medium—Gabbro
Dark and Fine—Basalt
Oceanic Igneous Rocks
• Types:
• Special: Glassy—obsidian
Light and Frothy—Pumice
Dark and Frothy—Scoria
Very Dark—peridotite
Igneous Rocks
• Types:
• Special: Glassy—obsidian
Light and Frothy—Pumice
Dark and Frothy—Scoria
Very Dark—peridotite
Igneous Rocks
Continental—gas is trapped in the rock
Continental—tossed into the air to cool by expanding gasses
Oceanic