| A | B |
|---|
| Absolute Age | The actual age in years of an event or object; can be determined using radioactive dating or tree rings. |
| Carbon Films | Created when an organism is buried in fine-grained sediments and its liquids and gases are squeezed out over time leaving behind a thin film of carbon in the shape of the organism. |
| Casts | These are formed when molds become filled with minerals |
| Crosscut | When an intrusion in rock is crossing the other layers of rock. |
| Extinction | The disappearance of all members of a species from Earth |
| Fossil Molds | These are visible shapes that are left after an animal or plant was buried in sediment and then decayed away. |
| Fossil Record | Information about past life, including the structure of organisms, what they ate, what ate them, in what environment they lived, and the order in which they lived. |
| Fossils | The preserved remains or traces of organisms that once lived on Earth. |
| Ice Cores | Used to analyze changes in Earth's atmosphere over time because they contain air from different periods in Earth's history. |
| Igneous Rocks | Fossils never form in this type of rock. |
| Index Fossil | A common fossil found in many areas from a specific time; used to help identify the age of other formations. |
| Law of Superposition | The geologic principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it. |
| Natural Evidence | Proof found in nature. |
| Original Remains | Fossils of actual bodies or parts of organisms, these are usually found in amber. |
| Petrified Wood | the stone fossil of a tree |
| Relative Age | The age of an event or object in relation to other events or objects. |
| Rocks | Made up of one or more mineral, named by how they are formed. |
| Sedimentary | Most fossils form in this type of rock. |
| Trace Fossils | Any indirect evidence of life preserved as an impression in rock; trails, footprints, tracks, burrows, and bite marks. |
| Tree Rings | These are used for studying the overall weather patterns over time - thin rings show dry years; thicker rings show wetter years. |
