1. archaean - Noun
2. archaean - Adjective
3. archaean - Adjective Satellite
4. Archaean - Proper noun
Ancient; pertaining to the earliest period in geological history.
The earliest period in geological period, extending up to the Lower Silurian. It includes an Azoic age, previous to the appearance of life, and an Eozoic age, including the earliest forms of life.
Source: Webster's dictionaryNevertheless, ancient Archaean lead ores of galena have been used to date the formation of Earth as these represent the earliest formed lead-only minerals on the planet and record the earliest homogeneous lead-lead isotope systems on the planet. Source: Internet
Oxygen levels of the Archaean Eon were negligible and today they are roughly 21 percent. Source: Internet
Temperature Even though during the Archaean solar radiation was reduced by 30 percent and the Cambrian Precambrian boundary by six percent, the Earth has only experienced three ice ages throughout the Precambrian. Source: Internet