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LITHOEN

Geological time unit

Archean

The eon following the Hadean, whose base is fixed at the age of the oldest well-dated terrestrial rocks. Ancient rocks of this age are found on every continent.

Classification

rank
eon

How this record is known

2
Settled consensus
Cited as the accepted position of the discipline.

2 of 2 claims on this page cite at least one registered source. Counts describe how each statement is known, not how likely it is to be true.

What Lithoen records

Each claim states how it is known and cites its evidence.

Established4,031 Ma before present

The base of the Archean is placed at 4,031 million years with an uncertainty of 3 million years.

  • definition basis: International Chronostratigraphic Chart v2024/12, which prints this boundary age as 4031 ± 3 Ma.
  • precision note: A boundary fixed near the age of the oldest well-dated terrestrial rocks.

Evidence support: Supported by the cited evidence one source

Evidence: Cohen 2024 Primary authority

Established4,031–2,500 Ma before present

On the International Chronostratigraphic Chart (v2024/12), the Archean spans 4031.0 to 2500.0 million years before present.

Not stated verbatim by the source — derived: base of the unit x base of the next younger unit -> span

A span is not stated anywhere on the chart: the chart gives boundary ages, and the span between two of them is composed from the two lines the premises cite.

  • definition basis: International Chronostratigraphic Chart v2024/12; the chronostratigraphic counterpart of the Archean is the Archean Eonothem.
  • precision note: The chart states that numerical ages are subject to ongoing revision and do not define units; GSSPs do.

Evidence support: Derived from the cited evidence one source

Evidence: Cohen 2024 Primary authority

In the knowledge graph

Record last updated 2026-09-06. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.