Building a Time Line

3. Rocks or sediment layers that are used as a marker to correlate rock layers.
4. Represents species that existed on Earth for a short length of time, were abundant, and inhabited many locations.
6. Not perfectly horizontal or vertical.
10. Information that shows.
12. Matching rocks and fossils from separate locations.

1. A surface where rock has eroded away, producing a break, or gap, in the rock record.
2. A model of Earth's history from its origin 4.6 billion years ago to the present called the _______ time scale.
5. Different in a way that is easy to notice.
7. To make visible; uncover.
8. To connect things, facts, or ideas where one thing depends on or affects the other.
9. To conclude from facts.
11. The length of time something continues.