| A | B |
|---|
| Age of the earth | 4.6 billion years old |
| James Hutton | The first to suggest the age of the earth |
| Principle of uniformitarianism | states that current geologic processes, such as volcanism and erosion, are some processes that were at work in the past |
| Strata | layers of rocks |
| Relative Age | Indicates that one layer is older or younger than another layer |
| Law of superposition | Attempting to determine the relative age of layer of sedimentary rock |
| Ripple marks | Small waves formed on the surface of the sand by the action of wind or water |
| Unconformity | Indicates that for a period of time deposition stopped, rock was removed by erosion, and then deposition resumed. |
| Stratified | Sedimentary rock |
| Stratified | Deposited in layers |
| Unstratified | metamorphic and igneous rock |
| Wnstratified | deep |
| nonconformity | an uncoformity in which stratified rock rests upon unstratified rock |
| Angular unconformity | occurs when rocks are deposited in horizontal layers are folded or tilted and then eroded |
| Discomformity | layers of rock are eroded, and a new layer of rock is placed on top of the eroded layer indicating a great lapse of time |
| law of crosscutting relationships | states that the fault or an intrusion is always younger than the rock layers it cuts through |
| Absolute age | the actual age of a rock layer |
| varve | layers of dark colored sediment and light colored sediment |
| Radioactive decay | some radioactive elements decay into other elements at a set and definite time |
| paleonologists | study fossils and learn about the earth's past |
| Evolution | the change in living things over time |
| Paleontology | the study of fossils |
| mummification | preservation of a dead organism by dying |
| amber | preservation in hardened tree sap |
| tar beds | preservation of an organism in thick petroleum oozing to the earth's surface |
| Freezing | preeservation of an organism in frozen soil and ice because not all bacteria can survive in those conditions |
| Petrification | the process by which minerals solutions such as ground water remove the original organic materials and replace them with other minerals |
| Trace fossils | tracks,footprints, borings, and burrows that are used to study the past |
| imprints | carbonized prints of leaves, stems, flowers, and fish made in clay or soft mud in clay sedimentary rock |
| molds | empty cavities where shells,trees, and other parts of organic material can collect; the mold retains the shape of the artifact |
| cast | a replica of the outer surface of the original organism |
| Coprolites | fertilized dung or waste materials from ancient animals |
| Gastroliths | stones found in the digestive tracts of some dinosaurs that were used to help grind food |
| Index Fossils | fossils that are found exclusively in rock layers of a particular geologic age |
