| A | B |
|---|
| Sediments deposited in layers form _________ rocks. | sedimentary |
| Gaps in rock layers are called _______. | unconformitites |
| Some unconformities are the result of ________. | erosion |
| Dinosaurs were alive on Earth for about ___ million years. | 160 |
| When the isotope decays, a new _______ is formed. | element |
| Calculating the absolute age of a rock is called ___________. | absolute dating |
| States that Earth's processes occurring today are similar to those that occurred in the past. | uniformitatianism |
| Fossil from a species that existed on Earth for a short period of time. | index fossil |
| Fossil made from a thin film of carbon atoms and molecules | carbon film |
| Remain, imprint, or trace of a once-living organism. | fossil |
| Hard and rocklike fossil. | petrified remain |
| Cavity left in rock by a decayed organism. | mold |
| Produced when a cavity is filled in with solid matter. | cast |
| Organisms have a better chance of being preserved if they have _____ parts. | hard |
| Scientists think that a _________ collided with earth and killed the dinosaurs. | meteorite |
| Sometimes layers of rock are overturned by forces generated by ___________. | tectonic activity |
| Determining the age of rocks examining their position in a layer is called __________. | relative dating |
| The time it takes for half of the atoms in the isotope to decay | half-life |
| States that the older rocks are at the bottom,and the younger at the top. | law of superposition |
| When a species becomes _______ there are no longer any living members of its kind. | extinct |
