Neoarchean

2.8 - 2.5 billion years ago - The Neoarchean Era, lasting from 2.8 to 2.5 billion years ago, was a highly dynamic phase that closed out the Archean Eon. During this era, Earth's internal heat flow began to cool slightly, allowing modern-style plate tectonics to establish a stronger foothold. Small crustal plates rapidly collided, forming massive granite-greenstone belts and building Earth's very first true supercontinent, Kenorland. Biologically, a massive revolution was quietly brewing in the global oceans. Oxygenic photosynthesis evolved significantly among early cyanobacteria, which clustered together in shallow waters to build extensive mat structures called stromatolites. While the atmosphere itself remained largely devoid of free oxygen during the Neoarchean, these microscopic organisms were producing the vast oxygen reserves that would completely alter global chemistry and trigger the Great Oxidation Event in the subsequent Proterozoic Eon.