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 Absolute dating | Uses the properties of atoms in rocks and other objects to determine the age |
| Angular unconformity | When rock layers become tilted |
| Carbonaceous film | Outline of an organism that forms when the organism is compressed and gases and liquids are forced out of the remains |
| Cast | Copy of an organism that forms when minerals fill a the spaced left when the organism decayed |
| Daughter material | Material that is produced when an isotope decays |
| Disconformity | Layers of rock are removed by erosion and new sediments are deposited on top |
| Fossil | Preserved remains or traces of living things |
| Half-life | Time it takes for half of the atoms in an isotope to decay |
| Index fossil | Fossil that can be used to date rock layers because it was alive for a short period of time |
| Isotope | Atoms of the same element that have different numbers of neutrons in their nucleus |
| Mold | Imprint in rock that forms after an organism decays |
| Nonconformity | Metamorphic or igneous rocks are present in layers of sedimentary rock |
| Original remains | Actual remains of an organism |
| Parent material | Isotope that breaks down and becomes another element |
| Petrified remains | Original material is replaced by minerals and becomes rock-like |
| Principle of Superposition | States that older layers of rock will be at the bottom and younger layers are at the top |
| Radioactive decay | Breakdown of an atom to form another atom |
| Relative dating | Determining the order of events using the position of rocks in a sequence |
| Trace fossil | Show evidence of animal activity |
| Example of petrified remains | dinosaur bones |
| Examples of original remains | frozen wooly mammoth and bugs in amber |
| Example of a mold | Imprint of a shell |
| Example of a trace fossil | Dinosaur footprints |
| Unconformity | Gaps in rock layers |