| Term | Definition |
|---|
| fossil | preserved remains or traces of living things |
| paleontologist | scientists who study fossils |
| sedimentary rock | type of rock made from hardened sediment |
| evolution | process in which all the different kinds of living things have changed over time |
| petrified fossil | fossil in which minerals have replaced all or part of an organism |
| mold | fossil formed when an organism buried in sedient dissolves, leaving a hollow area |
| cast | fossil that is a copy of an organisms shape, formed when minerals seep into the mold |
| trace fossil | fossil that provides evidence of the activities of ancient organisms |
| scientific theory | well-tested concept that explains a wide range of observations |
| extinct | type of organism that no longer exists anywhere on Earth |
| relative age | age of rock compared to age of other rocks |
| absolute age | nuber of years since rock formed |
| law of superposition | in horizontal layer of rock, the oldest layer is on the bottom |
| unconformity | a place where an old, eroded rock surface is in contact with a newer rock layer |
| fault | break or crack in Earth's lithosphere along which the rocks move |
| intrusion | igneous rock layer formed when magma hardens beneath Earth's surface |
| extrusion | igneous rock layer formed when lava flows into Earth's surface and hardens |
| index fossil | fossils of widely distributed organisms that lived during only on short period |
| atom | smallest particle of an element |
| element | type of matter in which all the atoms are the same |
| radioactive decay | breakdown of a radioactive element, releasing particles and energy |
| half-life | time it take for half of the atoms of a radioactive element to decay |
| geologic time scale | record of the geologic events and life forms in Earth's history |
| era | on of 3 long units of geologic time between the Precambrian and the present |
| invertebrate | animal without a backbone |
| period | one of the units of geologic time into which geologists divide eras |
| epoch | subdivisions of the periods of the geologic time scale |
| vertebate | animal with a backbone |
| amphibian | vertebrate that lives part of its life in the water and part on land |
| reptile | vertebrate with scaly skin that lays eggs with tough, leathery shells |
| mass extinction | when many types of living things became extinct at the same time |
| mammal | warm-blooded vertebrate that feeds its young milk |
Combine with other sets
Share on Facebook
Share on MySpace