Download intrusive rock

Earth Science
Chapter 8: Rocks
Lesson 2: Igneous Rocks
• Learning Targets
• By the end of the lesson, I will be able to:
1. Explain how igneous rocks form
2. Compare intrusive and extrusive igneous rocks
3. Identify samples of igneous rocks
• Pg 181 Textbook
How igneous rocks form
• Deep below earth’s surface temperatures reach around 1,400
degrees C
• Minerals melt to form magma (hot liquid rock formed inside the
earth)
• Magma sometimes rises through gaps in the surface of the
earth
• The rock cools thus forming igneous rock
Intrusive Rocks
• Igneous rock that forms underground is called intrusive rock
• Rock forms slowly (large crystals due to this)
• The size of the minerals crystals in an igneous rock are called
the rock’s texture
• Intrusive rocks have a course-grained texture
• Most common is granite
• Can be any color (mixture of minerals)
Extrusive rocks
• When magma reaches the earth’s surface it is called lava
• Lava cools and forms extrusive rock
• Cools quickly so does not have many crystals (fine-grain texture)
• Most common is basalt
• Volcanic eruptions
• Glassy texture
Recap
• Learning Targets
• By the end of the lesson, I will be able to:
1. Explain how igneous rocks form
2. Compare intrusive and extrusive igneous rocks
3. Identify samples of igneous rocks
• Assignment