About This Chapter
Geologic Time Scale - Chapter Summary
This chapter covers the earth's geologic time scale and examines several subdivisions of the earth's existence. You'll compare and contrast two different theories regarding the earth's formation and find out what preserved fossils can tell us about time.
Each lesson comes with a multiple-choice quiz that's designed to help you check your understanding of geological concepts and definitions. Feel free to reach out to our instructors if you have any questions about the lesson material, and you can supplement your studying by printing out the convenient lesson transcripts. You can also quickly find the information you need using the easy-to-navigate Dashboard and interactive video timelines for each lesson. These bite-sized and engaging lessons are also available to access at any time, day or night, and you can study them using any computer or mobile device. This chapter teaches you things like:
- The division of geological time, including major eons, eras, periods and epochs
- The differences between the theories of catastrophism and uniformitarianism
- How fossils are preserved
- The ways index fossils indicate time
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.
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.
3. Conditions of Fossil Preservation: Rapid Burial, Hard Parts & the Elements
Learn how fossils are formed and how varying conditions affect the preservation of organisms. What is the best way for a dinosaur to become fossilized? Find out here!
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.
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