History of Earth Vocab Review

Front

Age of rocks/fossils compared to others

Back

Relative Age

Front

Age of a rock in years since formation; the exact age.

Back

Absolute Age

Front

Geologic law stating that in horizontal sedimentary layers, each layer is older than the one above and younger than the one below.

Back

Law of Superposition

Front

Preserved remains or traces of living things.

Back

Fossils

Front

Determining the age of an object using the half-life of radioactive isotopes.

Back

Radioactive dating

Front

Nuclei of radioactive elements break down, releasing fast-moving energy particles.

Back

Radioactive Decay

Front

Record of geologic events and life forms in Earth's history, divided into Eons/Era/Periods/Epochs.

Back

Geologic Time Scale

Front

One of 3 long units of geologic time between the Precambrian & the present (Cenozoic/Mesozoic/Paleozoic)

Back

Era

Front

Unit of geologic time dividing eras: Cretaceous, Jurassic, Triassic

Back

Period

Front

Animal without a backbone

Back

Invertebrate