| A | B |
|---|
| remains | fossils are the ____, imprints, or traces of once-living organisms preserved in rock |
| fossil | A _____ may tell a geologist when, where, and how an organism lived |
| mold | A ____ is the cavity left behind in the rock after an organism's hard part has dissolved. |
| hard | The ____ parts of organisms are most likely to become fossils. |
| missing layer | An unconformity is a ____ of rock. |
| trace | Preserved animal tracks are called ____ fossils. |
| radioactive decay | Is measured in half-lives |
| carbon-14 | Fossils up to 75,000 years old can be dated with _____ |
