Take a Deep Breath--and Thank Mount Everest

From Science:

Next time you pause to view a scenic mountain vista, consider that the oxygen your lungs are taking in resulted from the same process that raised those peaks. Researchers have connected the periodic formation of supercontinents in Earth's geological past to the nourishment of tiny, oxygen-producing sea creatures, and the process continues to this day.

At least seven times, the massive plates that make up Earth's continents have slammed together--sometimes two at a time, and sometimes all of them--forming what geologists call supercontinents. Those gradual collisions severely warped the intervening crust and pushed up high mountain ranges, such as the Himalayas. Each time, over millions of years, wind and rain wore down those mountains into dust that was flushed into the sea. There, minerals containing iron, phosphorus, and other elements became food for microscopic plant life that flourished and, through photosynthesis, boosted the amount of oxygen in the atmosphere. The result, a team reported on 27 July in Nature Geoscience, was that atmospheric oxygen content rose from what they call negligible levels about 2.65 billion years ago to about 21% today.

More here.