Fossil Record Flashcards
a break in the geological record created when rock layers are eroded or when sediment is not deposited for a long period of time
uniformitarianism
a principal that states that geologic change occurs suddenly
catastrophism
the scientific study of fossils
paleontology
any method of determining whether an event or abject 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 as other atoms of the same element do but that has a different number of neutrons
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 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
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous.
unconformity
A mass extinction event is when species vanish much faster than they are replaced. This is usually defined as about 75% of the world’s species being lost in a ‘short’ amount of geological time
mass extinction
