Each sedimentary layer of rock represents 1,000 years of Earth's age, much like the rings of a tree. In undisturbed layers of sedimentary rock, the upper rock layers are older than the lower rock layers. In undisturbed layers of sedimentary rock, the lowest layers contain the older rocks. Rocks that form near volcanoes are older than surrounding rock.
I gave my students this multiple choice question: Which statement best describes the Law of Superposition?

Only one answer is correct among these 4 choices:
- Each sedimentary layer of rock represents 1,000 years of Earth's age, much like the rings of a tree.
- In undisturbed layers of sedimentary rock, the upper rock layers are older than the lower rock layers.
- In undisturbed layers of sedimentary rock, the lowest layers contain the older rocks.
- Rocks that form near volcanoes are older than surrounding rock.

Could you tell me which one is correct?

In undisturbed layers of sedimentary rock, the lowest layers contain the older rocks.