Paleoarchean

Paleoarchean
3600 – 3200 Ma Pha. Proterozoic Archean Had.
The Vaalbara continent, a continent dating from 2.7 to 3.6 billion years ago
Chronology
−3600 — – −3550 — – −3500 — – −3450 — – −3400 — – −3350 — – −3300 — – −3250 — – −3200 — – A r c h e a n Eoarchean Paleoarchean Mesoarchean ← Earliest definitive Stromatolites and uncontroversial life forms ← First photosynthetic organisms appeared[1] Events of the Paleoarchean. Axis scale: millions of years ago.
Proposed redefinition(s)	4031–3490 Ma Gradstein et al., 2012
Proposed subdivisions	Acastan Period, 4031–3810 Ma Gradstein et al., 2012 Isuan Period, 3810–3490 Ma Gradstein et al., 2012
Etymology
Name formality	Formal
Alternate spelling(s)	Palaeoarchaean
Synonym(s)	Early Archean
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Era
Stratigraphic unit	Erathem
Time span formality	Formal
Lower boundary definition	Defined Chronometrically
Lower GSSA ratified	1991[citation needed]
Upper boundary definition	Defined Chronometrically
Upper GSSA ratified	1991[citation needed]

The Paleoarchean (/ˌpeɪlioʊ.ɑːrˈkiːən, ˌpæl-/ PAY-lee-oh-ar-KEE-ən, PAL-), also spelled Palaeoarchaean (formerly known as the early Archean), is a geologic era within the Archean Eon. The name derives from Greek "Palaios" ancient. It spans the period of time 3,600 to 3,200 million years ago. The era is defined chronometrically and is not referenced to a specific level of a rock section on Earth. The earliest confirmed evidence of life comes from this era, and Vaalbara, one of Earth's earliest supercontinents, may have formed during this era.^[2][3]