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Geologic Clock With Events And Periods
2012-10-22 14:17:38

The Archean (formerly Archaeozoic) is a geologic eon between the Hadean and Proterozoic eons. The Archean Eon begins at roughly 3.8 billion years ago (Ga) and ends at about 2.5 Ga. But unlike all other geological ages, which are based on stratigraphy, The Archean eon is defined chronometrically. The lower boundary of 3.8 Ga has also not been officially recognized by the International Commission on Stratigraphy. The name Archean is derived from the ancient Greek (Arkhe), meaning...

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Word of the Day
ultimo
  • In the month which preceded the present; in the last month, as distinguished from the current or present month and all others.
  • In the month which preceded the present; in the last month, as distinguished from the current or present month and all others.
The word 'ultimo' comes from the Latin phrase 'ultimo mense', 'in the last month'.
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