Chapter 10
Chapter 10: Deep Time: How Old Is Old?
Animation
A cross-section through the earth reveals the variety of geologic features. View 1 of this animation identifies a variety of geologic features; View 2 animates the sequence of events that produced these features, and demonstrates how geologists apply established principles to deduce geologic history. For more information, see 10.3 Physical Principles for Defining Relative Age starting on p.279 and Figure 10.2 in your textbook.
The photo shows the Siccar Point unconformity in Scotland, on the coast about 60 km east of Edinburgh; the sketch shows a geologist’s interpretation of the unconformity. For more information, see 10.4 Unconformities: Gaps in the Record starting on p.281 and Figure 10.4 in your textbook.
This animation shows the stages in the development of three main types of unconformity in cross-section, and explains how an incomplete succession of strata provides a record of Earth history. View 1 shows a disconformity, View 2 shows a nonconformity and View 3 shows an angular unconformity. For more information, see 10.4 Unconformities: Gaps in the Record starting on p.281 and Figure 10.5 in your textbook.
When geologists examine a sequence of rocks exposed on a cliff, they see a record of Earth history that can be interpreted by applying the basic principles of geology, searching for fossils, and using radiometric dating. For more information, see The Record in Rocks: Reconstructing Geologic History on p. 291 in your textbook.
The succession of rocks in the Grand Canyon can be divided into formations based on notable changes in rock type and changes in fossil assemblages. For more information, see 10.5 Stratigraphic Formations and Their Correlation starting on p.282 and Figure 10.6 on p. 284 in your textbook.