Geology Reference
In-Depth Information
The areas on the other side of the globe where P waves or S waves do not appear be-
cause they either disappear or are
refracted
(change direction) are called
shadow zones.
For more details about P waves, S waves, and shadow zones and why geologists study
them, be sure to read Chapter 10.
Examining each layer
Another way scientists categorize the layers of earth's geosphere is by their composi-
tion, or the types of elements and minerals (explained in Chapter 5) that are found in
each layer. The different layers of the earth, their estimated depth, and their physical
properties are illustrated in Figure 4-4.
Figure 4-4:
The lay-
ers of the earth.
