||the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
||the unchanged fossilized remains of animals and plants.
||a core removed form an ice sheet
||The geologic age of a fossil organism, rock, or geologic feature or event defined relative to other organisms, rocks, or features or events rather than in terms of years.
||a fossil that is useful for dating and correlating the strata in which it is found.
||the true age of a rock or fossil.
||the time taken for the radioactivity of a specified isotope to fall to half its original value.
||the theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes.
|geological time scale
||a system of chronological measurement that relates stratigraphy to time,