Download Reinforcing Key Concepts

SECTION
EARTH HAS SEVERAL LAYERS.
BIG IDEA The
movement of tectonic plates causes geologic changes on Earth.
KEY CONCEPT
Earth has several layers.
Over millions of years,
Earth’s main layers, composed of dense and less dense materials, have formed. What
layers contain the densest materials? What layers contain the least dense materials?
1. Earth is made up of materials with different densities.
Scientists have been able to describe what
each layer is made of and how thick the layers are. In the diagram below, label each of
Earth’s layers. In the space provided, explain what each layer is made of.
Copyright © by McDougal Littell, a division of Houghton Mifflin Company
2. Earth’s layers have different properties.
B
C
D
A
These plates, called tectonic plates, fit
together like pieces of a jigsaw puzzle. Each plate has both continental crust and oceanic
crust. Because of this, an entire tectonic plate is actually much larger than the landmasses
seen on a world map. What part of a tectonic plate does a continent represent?
3. The lithosphere is made up of many plates.
EARTH’S HISTORY AND RESOURCES, CHAPTER 1, REINFORCING KEY CONCEPTS 21
CHAPTER 1
Plate Tectonics
1.1 Reinforcing Key Concepts