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Ch 9: Geological Time

About This Chapter

Use the following video lessons and quizzes to study the geologic time scale. Find out about theories in geological evolution and about geological dating.

Geological Time - Chapter Summary and Learning Objectives

As you make your way through this chapter, you'll find out how fossils are used to indicate time and what two primary methods are used in geological dating. You can learn about the Law of Superposition and the principles of original horizontality, along with the cross-cutting relationships principle.

Instructors will lead you through lessons on fossil preservation and the geologic time scale. You can impress your friends with your knowledge of the theories of catastrophism and uniformitarianism. Once you've watched all the video lessons in this chapter, you should be able to:

  • Explain major eons, eras, periods and epochs
  • Compare the two major theories in geological evolution
  • Define numerical and relative dating
  • Discuss the principles of radiometric dating
  • Describe the significance of half-life
  • Identify the conditions of fossil preservation
  • Explain the use of fossils in relative dating

Experienced and knowledgeable instructors lead these lessons on geological time. They create short, engaging video lessons that are easy to follow and provide all the information you need to know about this topic. After you watch the video lessons, you can gauge your understanding of the subject matter with the self-assessment quizzes that accompany each lesson.

Other resources available to you include lesson transcripts and links to text lessons that provide more detailed information on critical vocabulary terms. If you want to refer back to a major point in one of the lessons, you can also use the video tags that are provided in each lesson.

7 Lessons in Chapter 9: Geological Time
Test your knowledge with a 30-question chapter practice test
Geologic Time Scale: Major Eons, Eras, Periods and Epochs

1. Geologic Time Scale: Major Eons, Eras, Periods and Epochs

The geologic time scale is an essential tool for understanding the history of Earth and the evolution of life. In this lesson, explore the principal eons, eras, periods, and epochs that help us track major events in geologic history.

Theories of Geological Evolution: Catastrophism vs Uniformitarianism

2. Theories of Geological Evolution: Catastrophism vs Uniformitarianism

Geologists haven't always agreed about the history of our planet. They have debated between catastrophism and uniformitarianism over the last few hundred years! Learn about the two main theories of geologic evolution and how scientists came to resolve the dispute.

Methods of Geological Dating: Numerical and Relative Dating

3. Methods of Geological Dating: Numerical and Relative Dating

Learn how scientists determine the ages of rocks and fossils. We'll explore both relative and numerical dating on our quest to understand the process of geological dating. Along the way, we'll learn how stratigraphic succession and radioactive decay contribute to the work of paleontologists.

What is Relative Dating? - Law of Superposition, Principles of Original Horizontality & Cross-Cutting Relationships

4. What is Relative Dating? - Law of Superposition, Principles of Original Horizontality & Cross-Cutting Relationships

Discover how geologists study the layers in sedimentary rock to establish relative age. Learn how inclusions and unconformities can tell us stories about the geologic past. We'll even visit the Grand Canyon to solve the mystery of the Great Unconformity!

Principles of Radiometric Dating

5. Principles of Radiometric Dating

Radiometric dating is a method used to determine the age of rocks and other materials based on the rate of radioactive decay. Learn about three common types of radioactive decay: alpha decay, beta decay and gamma decay.

Radiometric Dating: Methods, Uses & the Significance of Half-Life

6. Radiometric Dating: Methods, Uses & the Significance of Half-Life

Radiometric dating is used to estimate the age of rocks and other objects based on the fixed decay rate of radioactive isotopes. Learn about half-life and how it is used in different dating methods, such as uranium-lead dating and radiocarbon dating, in this video lesson.

Relative Dating with Fossils: Index Fossils as Indicators of Time

7. Relative Dating with Fossils: Index Fossils as Indicators of Time

You may already know how to date a fossil with a rock. But did you know that we can also date a rock with a fossil? Watch this video to find out how we use index fossils to establish the relative ages of rocks.

Chapter Practice Exam
Test your knowledge of this chapter with a 30 question practice chapter exam.
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Practice Final Exam
Test your knowledge of the entire course with a 50 question practice final exam.
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