Download 3.2 Reinforcing Key Concepts

SECTION
VOLCANOES FORM AS MOLTEN ROCK ERUPTS.
3.2 Reinforcing Key Concepts
BIG IDEA Mountains
KEY CONCEPT
and valleys form as tectonic plates move.
Volcanoes form as molten rock erupts.
1. Volcanoes erupt many types of material. Some
of the heat inside Earth escapes to the
surface through volcanoes. A volcano is an opening in Earth’s crust through which many
types of materials erupt. The table below describes different types of volcanic materials.
Complete the table by filling in the missing information.
Molten Rock
Rock Fragments
cinders
CHAPTER 3
Mountains and Volcanoes
molten rock
after it erupts
tiny rock
fragments
less than 2
mm in size
main gases
in magma
2. Most volcanoes form along plate boundaries. What
are three areas where volcanoes
are likely to form?
3. Volcanoes can be many shapes and sizes. The
drawing below shows a cross section of
a volcano. What type of volcano is this? How can you tell?
4. Scientists monitor volcanoes. What
Copyright © by McDougal Littell, a division of Houghton Mifflin Company
magma
Volcanic Gases
indications do scientists use to predict a possible
volcanic eruption?
162 THE CHANGING EARTH, CHAPTER 3, REINFORCING KEY CONCEPTS
162-162-sean-urb-b0302-rkc 162
3/11/04, 9:07:48 AM