Apex Basalt, Australia
The Apex Basalt is a ca. 3.46-Ga-old formation comprising tholeiitic pillow basalts, komatiitic basalts, and komatiites intercalated with thin chert layers. It is located near Marble Bar in the Pilbara Craton of Western Australia. Microfossils, morphological biomarkers, and filamentous carbon structures in the lower chert beds have been interpreted as fossil prokaryotes (mainly cyanobacteria but also thermophiles) and are claimed to represent the oldest fossil record of life on Earth. For this reason, outcrops of this formation are considered one of the most important astrobiological sites on Earth.