Relative dating online activity
Hutton determined that the rocks were deposited over time. Hutton knew that deposition and erosion are very slow.
He realized that for both to occur would take an extremely long time.
Early geologists had no way to determine the absolute age of a geological material. What they could do was determine the ages of materials relative to each other.
If they didn’t see it form, they couldn’t know if a rock was one hundred years or 100 million years old. Using sensible principles they could say whether one rock was older than another.
Based on this information, they will learn how to relatively date associated artifacts.
Hutton saw that the lower rock layers are very old. There are no layers in between the ancient and recent layers.
Remember Nicholas Steno, who determined that fossils represented parts of once-living organisms? Superposition refers to the position of rock layers and their relative ages (Figure below).
Steno also noticed that fossil seashells could be found in rocks and mountains far from any ocean. Steno proposed that if a rock contained the fossils of marine animals, the rock formed from sediments that were deposited on the seafloor. Relative age means age in comparison with other rocks, either younger or older.
Then in Phase 2 of the project, the teacher will provide the students with plastic bins each representing a different stratum of the archaeological site.
Using the absolute dating principles provided in Phase 1 of the lesson, students will make decisions of which artifacts to send to a lab for absolute dating.