| Term | Definition |
|---|
| Fossil | Remains or traces of a once-living organism preserved in rock. |
| Petrified Remains | Fossils that form when some or all of the original materials that made up the organisms are replaced with minerals. |
| Carbonaceous Film | Fossil formed when the remains of a once-living organism are subjected to heat & pressure, leaving only a thin film of carbon behind. |
| Mold | Fossil formed when an organism is buried, decays, and leaves behind a hollow place in the rock. |
| Cast | Fossil formed when sediments fill a mold & hardens into rock. |
| Index Fossil | Fossil of species that existed on Earth for only a short time, were abundant, and widespread geographically; used by scientists to determine the age of rock layers. |
| Principle of Superposition | States that for undisturbed layers of rock, older rocks lie underneath younger & younger rocks. |
| Relative Dating | Method to determine the order of events & relative age of the rocks by examining the position of rocks in a sequence. |
| Unconformity | Gap in rock layers due to erosion, nodeposition, or both. |
| Absolute Dating | Process that uses properties of atoms in rocks & other objects to determine their exact ages, in years. |
| Radioactive Decay | Release of nuclear particles & energy from unstable atomic nuclei |
| Half-Life | Time needed for one-half the mass of a sample of a radioactive isotope to decay; can vary from fractions of a second to billions of years. |
| Radiometric Dating | Process to determine the absolute ages of rocks by measuring the amounts of parent & daughter materials in a rock & by knowing the half-life of the parent. |
| Uniformitarianism | States that Earth processes happening today are similar to those that happened in the past. |
Combine with other sets
Share on Facebook
Share on MySpace