FOSSIL RECORD Flashcards
Uniformitarianism
A principle that states that geologic processes that occurred in the past can be explained by current geologic processes.
Catastrophism
A principle that states that geologic change occurs suddenly.
Paleontology
The scientific study of fossils.
Relative Dating
Any method if determining whether an event or object is older or younger than other events or objects.
Superposition
A principle that states that younger rocks lie above older rocks if the layers have not been disturbed.
Geologic Column
An arrangement of rock layers in which the oldest rocks are at the bottom.
Absolute Dating
Any method of measuring the age of an event or object in years.
Isotope
An atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but has a different number of neutrons (and thus a different atomic mas).
Radioactive Decay
The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element.
Radiometric Dating
A method of determining the age of an object by estimating the relative percentages of a radioactive (parent) isotope and a stable (Daughter) isotope.
Half- Life
The time needed for half of a sample of a radioactive sub-stance to undergo radioactive 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 moment of an animal.
Mold
A mark or cavity made in a sedimentary surface by a shell or other body.
Cast
A type of fossil that forms when sedimentary fill in the cavity left by a decomposed organism.
