Fossil Record Flashcards
uniformitarianism
a principle that states that geologic processes that occured in the past can be explained by current geologival processes
catastrophism
a principle that states that geologic change occurs suddenly
paleontology
the scientific study of fossils
relative dating
any method of determining whether an event or object is older or younger than other events or objects
absolute dating
any method of measuring the agent an event or object in years
superposition
a principle that stated that younger rocks lie above older rocks if the layers hav not been disturbed
isotope
A form of a chemical element in which the atoms have the same number of protons (part of the nucleus of an atom) but with a different number of neutrons (part of the nucleus of an atom)
radioactive decay
the process in which a radioactivity isotope tends to break down into a stable isotope of the same element or another element
half-life
the time needed for half of a sample ofa radioactivitysubstance to undergo radioactivite decay
fossil
the remains or physical evidence of an organism preserved by geological processes
trace fossil
a fossilized mark that is formed in soft sediment by the movement of an animal
mold
a mark or cavity made in a sedimentary surface by a shell or other body
cast
a type of fossils that forms when sediment fill in the cavity left by a decompsed organism
unconformity
a break in the geologic record created when rock layers are eroded or when sediment is not depostied for a long period of time
mass extinction
when species vanish much faster than they are replaced.
