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Clues to Earth's Pas
Term | Definition |
---|---|
Fossils | are the preserved remains or evidence of ancient living things |
Catastrophism | is the idea that conditions and organisms on Earth change in quick, violent events |
uniformitanism | states that geologic processes that occur today are similar to those that have occurred in the past |
carbon film | is the fossilized carbon outline of an organism or part of an organism |
mold | is the impression in rock left by an ancient organism |
cast | is a fossil copy of an organism made when a mold of the organism |
trace fossil | is the preserved evidence of the activity of an organism |
paleontologists | scientists who study fossils |
relative age | is the age of rocks and geologic features compared with other rocks and features nearby |
superposition | is the principle that in undisturbed rock layers, the oldest rocks are on the bottom |
inclusion | a piece of an older rock that becomes part of a new rock |
uncomformity | is a surface where rock has eroded away, producing a break, or gap, in the rock record |
correlation | matching rocks and fossils from separate locations |
index fossil | represent species that existed on Earth for a short length of time, were abundant, and inhabited many locations |
absolute age | to mean the numerical age, in years, of a rock or object |
isotope | are atoms of the same element that have different numbers of neutrons |
radioactive decay | is the process by which an unstable element naturally changes into another element that is stable |
half-lif | is the time required for half of the parent isotopes to decay into daughter isotopes |