1Of, relating to, or denoting the eon that constitutes the earlier (or middle) part of the Precambrian, in which there was no life on earth. It precedes the Proterozoic eon. Also called azoic.
More example sentences
- The answers to questions about early life on Earth are preserved in the oldest rocks, and Canadian earth scientists include some of the world's best Archean geologists and laboratories equipped to study Archean rocks.
- The geological history of Archaean greenstone belts is controversial and, to date, no tectonic model for their evolution has been agreed upon.
- The contacts between the complex and the Archaean metamorphic rocks are intrusive.
The Archean extended from the origin of the earth (see Precambrian) to about 2,500 million years ago. In models that include the Priscoan eon, the Archean began about 4,000 million years ago
late 19th century: from Greek arkhaios 'ancient' + -an.
Definition of Archean in:
- The British & World English dictionary