Warrawoona Group

The Warrawoona Group is a geological unit in Western Australia containing putative fossils of cyanobacteria cells. Dated between 3.53–3.427 Ga, these microstructures, found in Archean chert, are considered to be the oldest known geological record of life on Earth.

The fossils in this group were discovered by Arthur Hugh Hickman in 1983 in Warrawoona, 21°42′S 118°0′E / 21.700°S 118.000°E / -21.700; 118.000 (Warrawoona), a region on the Pilbara craton in the northern part of Pilbara province.

Whether or not the fossils were authentic was disputed in the past, as abiotic processes could not be ruled out. Currently the fossils are thought to be of biological origin, however there is no conclusive evidence of fossilized organisms in the formation, and whether the lines in the rock are fossilized stromatolites.

The rocks also include felsic volcanic rocks.