Era: The second largest division of time in the Geologic Time Scale, e.g., Mesozoic.
Eon: The largest division of time in the Geologic Time Scale, e.g., Phanerozoic.
Fauna: The animals of a given region or period.
Flora: The plants of a given region or period.
Fossil Record: All of the fossils that have existed throughout Earth’s history, whether they are in the ground or are in a museum.
Geologic Time Scale: A vertical timeline representing events in Earth’s history. The Geologic Time Scale is divided
into blocks of time that represent great changes in Earth’s biodiversity.
Law of Superposition: The formation of new rock layers on top of older ones. This allows us
to determine the relative age of rocks and fossils. "Super" refers to over and "position" refers to place.
Period: The third largest division of time in the Geologic Time Scale, e.g., Cretaceous.
Radiometric dating: A method used to determine the absolute age of a rock by using the rock's chemistry.
Relative age: The age of a rock layer, or the fossils it contains, compared to other layers.