fossil record Flashcards
a principle that states that geologic processes that occurred in the past can be explained by current geologic process
uniformitarianism
a principle that states that geologic change occurs suddenly
catastrophism
the scientific study of fossils
paleontology
any method of determining whether an event or object is older or younger than other events or objects
relative dating
any method of measuring the age of an event or object in years
absolute dating
a principle that states that younger rocks lie above older rocks if the layers have not been disturbed
superposition
an atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and thus a different atomic mass)
isotope
the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element
radioactive decay
the time needed for half of a sample of a radioactive substance to undergo radioactive decay
half-life
the remains or physical evidence of an organism preserved by geological processes
fossil
a fossilized mark that is formed in soft sediment by the movement of an animal
trace fossil
a mark or cavity made in a sedimentary surface by a shell or other body
mold
a type of fossil that forms when sediments fill in the cavity left by a decomposed organism
cast
a surface of contact between two groups of unconformable strata
unconformity
the extinction of a large number of species within a relatively short period of geological time
mass extinction
