| A | B |
|---|
| fossil | preserved remains or evidence of organsims |
| trace fossil | evidence of an organism's activities |
| petrifaction | process in which minerals replace an organsim's tissues |
| permineralizatioon | process in which the pores in an organism's hard tissue is filled with minerals |
| replacement | process in which minerals take the place of all of an organism's tissue |
| amber | hardened tree sap |
| asphalt | thick, oily, petroleum substance |
| burrow | underground shelters |
| coprolite | petrified feces |
| trail | imprint left by animals such as slugs, snail |
| mold | cavity made in a sediment surface after an organism decays |
| cast | solid outer replica of an organsim formed when sediments or minerrals fill in a cavity |
| index fossils | fossils that are widely distributed geographically and lived during a brief period |
| ammonites | index fossil similar to a modern squid that lived between 230 and 208 million years ago |
| trilobite | index fossil that lived about 400 million years ago |
| geologic time scale | standard division of Earth's history based on geologic events and life forms |
| eon | largest division of geologic time |
| era | second-largest division of geologic time; includes two or more periods |
| period | third-largest division of geologic time |
| epoch | smallest division of geologic time; subdivision of a period |
| Cenozoic Era | means recent life |
| Paleozoic Era | means ancient life |
| Mesozoic Era | means middle life |
| Cenozoic Era | Age of Mammals |
| Mesozoic Era | Age of Reptiles |
| Paleozoic Era | Age of Amphibians |
| Paleozoic Era | Age of Invertebrates |
| Paleozoic Era | Age of Fishes |
| extinction | death of every member of a species |
| ice core | tubular or cylinder-shaped sample of ice |
| Phanerozoic | most recent eon |
| Phanerozoic | means visible light |
| Holocene | the current epoch |
| Quaternary | the current period |
| principle of superposition | when rock layers are undisturbed, the oldest are on the bottom |
| principle of cross cutting relations | features such as intrusions, folding, faulting are always younger than the rocks through which they cut |
| principle of horizontality | rock layers are deposited parallel to Earth's surface |
| intrusion | igneous rock that cuts through rock layers beneath Earth's surface |
| half-life | the amount of time required for half of a radioactive isotope to decay to daughter isotope |
| radiometric decay | the process by which unstable isotopes (parent) break down into stable isotopes (daughter) |
| radioactive dating | finding ages of rocks and fossils based on the ratio of parent to daughter isotopes in rock or fossils |
| absolute dating | finding the age in years |
| relative dating | comparison of an object or event to another object or event to determine age from oldest to youngest |
