| A | B |
|---|
| geology | the study of the earth’s layers of soil and rock,  |
| paleontology | the study of fossils and other ancient life forms,  |
| fossil | the shape of an animal or plant from long ago preserved as rock,  |
| cast fossil | a fossil formed when sediments fill a mold, it takes on the same outside shape as the living thing that shapes the mold,  |
| mold fossil | a fossil imprint made by the outside of a dead plant or animal,  |
| trace fossil | a fossil that shows changes that long-dead animals made in their surroundings,  |
| decay | to break down and return materials to the environment,  |
| remains | what is left after a living thing dies,  |
| extinct | plants and animals that no longer live on Earth,  |
| ancient | very old, belonging to a time long ago,  |
