Origin of Atmospheric Oxygen Discovered

via ScienceDaily, some new evidence has been discovered from the analysis of ancient rocks regarding the origin of oxygen in the Earth's atmosphere 500 million years ago. The surprising part is that the oxygen developed extremely quickly by geologic standards - only 2 million years. Tectonic upheavals led to an increase in terrestrial weathering from the sulferous atmosphere at the time, which caused a decrease in the amount of carbon in the atmosphere, leading to the then much warmer Earth to cool globally. The carbon levels dropped from as much as 20 times greater than today, trapped in seabed sediments after the weathering process. This oxygen increase in turn led to the evolution of oxygen producing algae spreads in the oceans, further tipping the balance of gasses in the atmospheric blanket towards oxygen.

"Tectonic activity led to increased weathering, which pulled carbon dioxide from the air and cooled the climate. Then, as the oceans cooled to more hospitable temperatures, the plankton prospered -- and in turn created more oxygen through photosynthesis."

This set of conditions persisted for around 50 million years, during which time new plant and animal species flourished, but the cooling trend accelerated with new tectonic events creating the US Applachian mountain range, leading to a severe cooling trend that resulted in a ice age so extensive that it killed off nearly half of all species living on the planet at the time, around 450 million years ago.