Eoarchean

The first era of the Archean Eon, spanning approximately 4.0 to 3.6 billion years ago. Its rocks preserve evidence about early crust, oceans, and possible life.

Archean: A geologic eon lasting from about 4.0 to 2.5 billion years ago, before the Proterozoic Eon. The Eoarchean is the Archean’s first era.
Acasta Gneiss: A Canadian rock formation containing some of the oldest known remnants of Earth's continental crust. Its oldest dated rocks approach the beginning of the Eoarchean.
Plate tectonics: The movement and interaction of lithospheric plates over Earth's ductile mantle. Whether modern-style plate tectonics operated in the Eoarchean remains debated.
Origin of life: The emergence of the first living systems from nonliving chemical processes on Earth. The Eoarchean may contain evidence relevant to when life first emerged.
Hadean: The earliest geologic eon, preceding the Archean and ending about 4.0 billion years ago. It immediately precedes the Eoarchean, though its rock record is sparse.
Isua Greenstone Belt: A region in southwest Greenland containing some of Earth's oldest extensively studied supracrustal rocks. Its rocks record Eoarchean conditions near the era's end.
Mantle convection: The slow circulation of Earth's mantle driven by internal heat and buoyancy differences. It supplied heat and helped drive early crust formation and recycling.
Evidence of early life: Geological and chemical traces used to assess whether ancient environments hosted living organisms. Claims for Eoarchean life depend on interpreting ambiguous traces in altered rocks.
Paleoarchean: The second era of the Archean Eon, spanning approximately 3.6 to 3.2 billion years ago. It begins where the Eoarchean ends.
Nuvvuagittuq Greenstone Belt: A rock belt in Quebec whose proposed age and interpretation remain contested. Its disputed antiquity bears on how much crust formed during the earliest Archean.

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