1) Era 
The Neoarchean (ən; also spelled Neoarchaean) is a geologic era within the Archaean. It spans the period of time from {Ma|Neoarchean|Paleoproterozoic}—the period being defined chronometrically and not referenced to a specific level in a rock section on Earth. Oxygenic photosynthesis first evolved in this era and was accountable for the oxygen c...