Lesson 5 – Igneous Rock

Earth Unit

Objectives

•Students will identify the characteristics of igneous rock.•Students will understand how rocks are formed.

Vocabulary

• Igneous rock: rocks formed when magma from inside the earth cools and hardens on the earth’s surface.• lava: magma that has

reached the surface of the earth• magma: hot, liquid rock

formed deep inside the earth

a rock is made of two or more minerals.

ROCKS ARE DIVIDED INTO THREE GROUPS BASED ON HOW THE ROCKS FORMED

hOW ARE rOCKS fORMED?

• Today we will be using the rock formation chart to help us understand the formation and location of igneous rocks.

• Materials:• red and orange

crayon• pencil• formation chart

Igneous rocks or fire rocks are formed from hot, molten materials called magma.  They can be found where volcanoes have or do exist.

Magma is is

found beneath

the earth’s

surface.

Igneous rocks are created when molten rock (lava) inside the Earth pushes through the crust (like in a volcanic eruption) and then cools

Intrusive (plutonic) Igneous Rocks

• Intrusive rocks are made when magma that is blocked from reaching the earth’s surface cools slowly below the earth’s surface. Intrusive igneous rocks cool slowly deep within the earth and produces large crystals.

click here for more examples

Color the magma

orange, stop before

reaching the earth’s

surface.

QUARTZ GRANITE

intrusive igneous Rocks

The slow-cooling process creates large crystals and appear coarse-grained. Some examples of these are:

GABBRO

Extrusive (volcanic) igneous rocks

• Lava is the name for liquid magma that reaches the earth’s surface by flowing out of volcanoes. • The lava cools rapidly

forming extrusive rocks which have small, fine grained crystals or glassy appearance.

Color the lave red

click here for more examples

If the cooling is instantaneous a glassy texture

may form

If gas bubbles are trapped as the

lava rapidly cools a vesicular

texture may occur

EXTRUSIVE igneous Rocks

OBSIDIAN PUMICE

is a fine-grained, dark-colored

extrusive igneous rock

BASALT

https://www.youtube.com/watch?v=PrN7jygu4cQ

Review

•With a partner and your chart explain:•How igneous rocks are formed•What magma is and where it can be found•What lava is and where it can be found• Intrusive and extrusive rocks