About This Chapter
Geologic History - Chapter Summary
These comprehensive and engaging geology lessons summarize the geological history of the planet Earth. You'll begin the chapter by reviewing the principles of uniformitarianism and taking a close look at radioactive dating using fossils. The chapter continues with a summary of the entire geologic time scale and a differentiation between relative and absolute time in the study of geology. After completing the lessons in this chapter, you should be able to:
- Understand the principles of uniformitarianism
- Share the law of superposition
- Define and explain rock strata
- Understand how index fossils are indicators of time
- Know what radioactive dating is
- Differentiate between relative and absolute time in geology
- Summarize the major eons, eras, periods and epochs on the geological time scale
- Identify the characteristics of various fossil types
- Explain geologic history and Earth processes
This geology chapter is taught by expert instructors who craft each lesson with simplicity and efficiency in mind. This way, you can be sure you're covering the most important geology topics as quickly as possible. After you complete a lesson, try taking its accompanying self-assessment quiz to make sure you comprehend the material. These lessons can be reviewed as many times as needed, and you can print the word-for-word transcripts for further study. The chapter is also available at any time that fits your schedule. You can access it using your desktop, laptop, mobile device or tablet.
1. Uniformitarianism: Definition, Principles & Examples
Uniformitarianism is an important concept in geology that addresses the consistent behavior of geological processes over time. Learn about the concept and significance of uniformitarianism in this lesson, and then test your knowledge with a quiz.
2. Law of Superposition: Definition & Concept
Superposition is one of the fundamental principles of stratigraphy. It is also a statement of the obvious (or seems to be). You will learn all about the concept in this lesson.
3. Rock Strata: Definition & Explanation
Rock strata are found almost everywhere, even on the tops of mountains. In this lesson, we'll learn what rock strata look like, how they form, and their importance to geologists. Then you can test your knowledge with a short quiz.
4. 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.
5. What is Radioactive Dating? - Definition & Facts
Discover how scientists determine the age of fossils, rocks, and other geologic phenomena by using the known half-lives of isotopes within each specimen, a technique known as radioactive dating.
6. Relative vs. Absolute Time in Geology
You may not associate geology with time, but the former greatly depends on the latter. In this lesson we'll discuss both absolute and relative time, and how they work together to give us a detailed history of Earth.
7. 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.
8. Fossil: Definition, Types, Characteristics & Examples
Fossils provide scientists with many clues about Earth's history, offering evidence of dinosaurs and strange plants that existed in the past. This lesson will define a fossil, look at different types and characteristics of fossils, and then describe how fossils are formed.
9. Fossil Record: Definition & Examples
This lesson teaches you about the fossil record. It explains how scientists learn about Earth's distant past and highlights what fossils can tell scientists about ourselves and other organisms.
10. Earth Processes & Geologic History
In this lesson we will learn about Earth's myriad geologic processes and examine how they have changed its surface and materials over the course of geologic history.
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