Mesoarchean

3.2 - 2.8 billion years ago - The Mesoarchean Era spanned from 3.2 to 2.8 billion years ago, a deep geological period defined by a gradually stabilizing planet. The global climate was generally warm, and the atmosphere remained thick with methane and carbon dioxide, lacking any free oxygen. Oceans covered the vast majority of the planet's surface, though early continental landmasses, such as the ancient craton of Ur, began to expand through intense volcanic activity and tectonic collisions. Microscopic life continued to expand across these shallow marine environments. The oldest definitive fossilized stromatolites - layered structures created by the trapping and binding of sediment by microbial mats - date back to this era in Western Australia. These early microbial communities thrived under a faint young sun, steadily adapting to their environment and laying the foundational groundwork for future biological and atmospheric transformations.