This episode explores aspects of geologic time or “deep time” beginning with a review of humankind’s thinking about the Earth’s age. Students learn about the concept of relative time by exploring superposition, unconformities and event sequencing. Students learn about the history of the geologic time scale and the scale’s division into eras, periods and epochs. Students examine problems involved with using relative dating to determine exact dates of events. The video also introduces absolute time. Students visit the radiometric laboratory at the University of North Carolina at Chapel Hill where radioactive decay is explored as a method for dating rocks. This episode concludes with a walk through Earth’s history using a football field for scale.

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