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