Paleoarchean

Paleoarchean Eon 3600–3200 million years ago

The geological eons and eras view • discuss •  -4500 — – -4000 — – -3500 — – -3000 — – -2500 — – -2000 — – -1500 — – -1000 — – -500 — – 0 — Hadean Archean Protero -zoic Phanero -zoic Eo Paleo Meso Neo Paleo Meso Neo Paleo Meso Ceno     Scale: Millions of years

A stromatolite formed by Paleoarchean miocrobial mats, preserved as a fossil, from Pilbara craton, Western Australia

The Paleoarchean (/ˌpeɪlɪ.oʊ.ɑːrˈkiːən/; 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. 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.