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Precambrian Reference Libraries

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Neoproterozoic
2012-11-18 19:10:56

The Neoproterozoic is the third of three subdivisions of the Proterozoic Eon (occurring from 1 billion years ago to 542 million years ago). This terminal era of the Proterozoic is itself divided into three sub-periods called the Tonian, Cryogenian, and Ediacaran Periods. The most severe glaciation known in the geologic record occurred during the Cryogenian Period, when ice sheets reached the...

Archean
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...

Hadean Eon
2012-06-26 19:51:17

The Hadean is the unofficial geological period of time that lies just before the Archean time period. The Hadean began with the formation of the Earth roughly 4.5 billion years ago (Ga) and ended about 3.8 Ga; the latter date varies according to different sources. Hadean is derived from Hades, Greek for “underworld,” referring to the hellish conditions on the planet at the time. The term...

Word of the Day
saggar
  • A ceramic container used inside a fuel-fired kiln to protect pots from the flame.
The word 'saggar' may come from 'safeguard'.
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