Geologic Time Scale Vocab

Front

Technique to date materials (rocks) via radioactive decay rates.

Back

radiometric dating

Front

Division of geologic time, a subdivision of an era, further divided into epochs.

Back

period

Front

Fossils of organisms that existed in large numbers for a short geologic time; used to date rocks.

Back

index fossil

Front

Beginning of the Paleozoic Era, 540-485 million years ago

Back

Cambrian Period

Front

Longest division of geologic time scale

Back

eon

Front

Biological process in plants, algae, and some bacteria that converts water and CO2 into organic compounds using solar energy.

Back

photosynthesis

Front

Age in years of a fossil, rock, feature, or event, usually via radiometric dating.

Back

absolute age

Front

A large landmass formed by converging continents.

Back

supercontinent

Front

Record of geologic time divided into eons, eras, periods, epochs, and ages.

Back

Geologic time scale.

Front

Rapid growth in life's diversity (540-485 million years ago)

Back

Cambrian explosion