Section Warm-Up
How well could you tell the story of the history of the United States if you did not know the order in which major events took place? To tell America’s history, you need to know when events happened, relative to each other. For example, the signing of the Declaration of Independence came before the Revolutionary War and the expansion westward took place after transportation developments, like the invention of the steam engine.
Telling a story of geologic history is similar: You need to know the order in which things took place so you can tell the story of how Earth has changed over time. Relative dating is all about placing things in sequential order. The scientists who do it have to be good rock detectives. Study the image on the right and then answer the question below.
