| A | B |
|---|
| fossils | the traces or preserved remains of once living things |
| paleontologist | scientist who studies fossils |
| sedimentary rock | type of rock fossils form in |
| petrified fossil | the type of fossil in which all or part of a remain is replaced with minerals |
| carbon film | the type of fossil formed when carbon is left behind from the remains of a living thing |
| mold | the part of a fossil represented by the modeling clay in our project |
| cast | the part of the fossil represented by the dried glue in our project, created a replica of the original remains |
| trace fossil | a fossil that tells us something about a living things past activities |
| trace fossil | A footprint is an example of a ___________. |
| tar, amber, and ice | three materials that may preserve remains of a once living thing |
| fossil record | keeps track of the changes in an organism over time |
| evolution | the changes in organisms over thousands of years |
| relative age | the age of a rock found by comparing it to other rocks around it |
| absolute age | the age of a rock based on the number of years that has passed since it was formed |
| relative age | If I said you were older than Suzie and younger than Billy, I'd be talking about your ________. |
| absolute age | If I said you are exactly 16 years, 12 days, and 3 hours old, I'd be talking about your _________. |
| law of superposition | The _________ states that in sedimentary rock layers, the oldest rocks are on the bottom and the newest are closer to the surface. |
| unconformity | a place in sedimentary rock layers where a younger rock meets a rock that is much, much older. |
| unconformity | a gap in the geologic record |
| index fossils | help geologists match rock layers |
| atoms | all matter is made of these tiny particles |
| element | forms when all atoms of a particular type of matter are the same |
| radioactive decay | when unstable elements break down by releasing particles or energy, atoms of one element break down to form atoms of another element |
| half-life | the time it takes for half of that atoms of a radioactive element to decay |
| carbon-14 and potassium-40 | two radioactive elements used to date fossils |
| igneous | type of rock that can be dated with radioactive dating |
| sedimentary | type of rock that can't be dated with radioactive dating, due to particles of differing ages |
| 4.6 billion year old | age of earth |
| geologic time scale | Scientists made the __________ because the time span of Earth's history is so long. |
| changes | Geologists use ______ in the forms of life on Earth as markers to end and begin units of time on the geologic time scale. |
| Paleozoic Era | era that means "ancient life" |
| Mesozoic Era | era that means "middle life" |
| Cenozoic Era | era that means "recent life" |
| Precambrian | period when Earth formed |
| Cambrian | period where life "exploded" or many organisms appeared |
| Devonian | period where animals came to land |
| mass extinction | ended the Paleozoic Era |
| Permian | period when Pangea was formed |
| Mesozoic | era known as the "Age of Reptiles" |
| Triassic | period when mammals appeared |
| asteroid | One theory scientist have on the mass extinction that ended the Mesozoic Era is that an _______ struck Earth and covered the land in dust that killed plants and affected the food chain. |
| climate | Some scientists think that the mass extinction at the end of the Mesozoic Era was caused by a change in ______ due to extreme volcanic activity. |
| Quaternary | In what period of the Cenozoic Era do we live? |
