Fossils

fossil: are the remains, imprints, or traces of prehistoric organism.

Permineralized remains: are fossils in which the spaces inside are filled with monerals from groundwater.

Carbon film: a thin film of carbon residue is left, forming a silhoutte of the original organism.

Mold: the hard part might decay and dissolved, leaving behind a cavity in the rock.

Cast: a type of fossil that forms when crystals fill a mold or sediments wash into a mold and harden into the rock.

Index Fossils: remains of fossils that existed on Earth for a relatively short period of time, where abundant and widespread geographically.

Principle of superposition: states that in udisturbed rock layers, the oldest rocks are on the bottom and the rocks become progressively younger toward the top.

Relative age: is its age in comparison to other thing.

Unconformity: gap in the rock layer that was abundant in Paleozic oceans and is considered to be a index fossil.

Abosute age: age, of a rock or other object; can be determined by using properties of the atoms that make up materials.

Radioactive decay: process of breaking down.

Half-life: time it takes for half the atoms of an isotope to decay.

Radiometric dating: process used to calculate the absolute ageof rock by measuring the ratio of parent isotope to daughter product in a mineral and knowing the half-life of the parent.

Uniformitarianism: principle stating that Earth process ocurring today are similar to those that occured un the past.