Paleoarchean

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Paleoarchean Eon
3600–3200 million years ago
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Millions of years
A stromatolite formed by Paleoarchean miocrobial mats, preserved as a fossil, from Pilbara craton, Western Australia

The Paleoarchean (pronunciation: /ˌplɪ..ɑːrˈkən/; also spelled Palaeoarchaean (formerly known as early Archean)) is a geologic era within the Archaean. It spans the period of time 3,600 to 3,200 million years ago—the era being defined chronometrically and not referenced to a specific level in a rock section on Earth. The name derives from Greek "Palaios" ancient. The oldest ascertained life form (well-preserved bacteria older than 3,460 million years found in Western Australia) is from this era. 3,480 Ma: Fossils of microbial mat found in 3.48 billion-year-old sandstone discovered in Western Australia.[1][2] The first supercontinent Vaalbara formed during this period.

During this era, a large asteroid, about 37 to 58 kilometres (23–36 mi) wide, collided with the Earth about 3.26 billion years ago, creating the features known as the Barberton greenstone belt.[3]

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