Absolute dating lesson plan
Pretty obvious that the dike came after the rocks it cuts through, right?
With absolute age dating, you get a real age in actual years.
You might have noticed that many of the oldest age dates come from a mineral called zircon.
For example, which is older, the bricks in a building or the building itself?
Are there repairs or cracks in the sidewalk that came after the sidewalk was built?
Unlike people, you can’t really guess the age of a rock from looking at it.
Yet, you’ve heard the news: Earth is 4.6 billion years old. That corn cob found in an ancient Native American fire pit is 1,000 years old. Geologic age dating—assigning an age to materials—is an entire discipline of its own.
The narrower a range of time that an animal lived, the better it is as an index of a specific time.