S3.11.8 For the adult
Reading Earth's history
How can a rock tell us about a time long before people?
What this chapter teaches
Layers of sedimentary rock settle one on top of another, so the lowest layer is usually the oldest. Fossils in the layers are evidence of what lived there and what the place was like. The Earth is about 4.6 billion years old, and people have lived on it for a tiny part of that time.
Three questions to ask
There is no one right wording. Listen for the idea.
- In a cliff of layers, which layer is usually the oldest, and why?
- What would a fossil shell on a mountain top tell you?
- How could you build a model of layers at home?
After the chapter, the learner can
- Explain why lower rock layers are usually older
- Explain what fossils tell us about life long ago
What they copy into their notebook
Layers settle one on another, so the lowest is usually the oldest. Fossils are evidence of what lived there. The Earth is about 4.6 billion years old.