This is one of four notes for my feature on forest bathing in Cheasty Greenspace.
For reasons unknown, algae left the sea and decided to give the land a shot 450 million years ago. These adventurers evolved into plants. These plants evolved into tall beings we call trees. The way to tree-ness was opened by the wonderful substance called wood. For millions of years, no living thing could break it down. This victory over life (and also death) gave us the carboniferous period (359 to 299 million years ago).
The dead trees of that age went under as is. Lignin, the key material of wood, was just too tough. It imprisoned the food of wood and buried it. And each burial put pressure on the burial before. As gravitational pressure turns hydrogen clouds into a star, the burial pressure turned the trees into peat. This peat became coal. But think about it for a moment. Beating bacteria and fungi for millions upon millions of years is something that dwarfs all of the achievements of the organ that evolved in the African ape and now calls itself the most complicated thing in the known universe: the human brain.
Then 299 million years ago, the lock of lignin was opened and a new feast began. That feast is still with us to this day; it's all over the forest floor and has a strong smell when it rains. Indeed, this feast is one of the big reasons why the trees of our age will never provide the carbon sink that the pre-feast trees did. The great burial is over. The carbon released by our fossil-burning civilization is never going back into the ground, back into that eonic tomb.