What does the study rock layers tell us about the layers that are at the surface compared with the layers that are deeper underground

Sedimentary rock layers contain information about the relative ages of events and objects in Earth's history. As you read earlier, sedimentary rocks form from the sediments that fall to the bottom of lakes, rivers, and seas. Over time, the sediments pile up to form horizontal layers of sedimentary rocks

The rock layers above the bone bed are younger than the bone bed. The rock layers below the bone bed are older than the bone bed.