Ancient wildfires

[Blob]

UK scientists have traced the history of wildfires by studying lumps of ancient charcoal from around the world.

The fossils show the incidence of fires through time is closely related to the level of atmospheric oxygen.
Andrew Scott and Ian Glasspool say huge swathes of the planet were ablaze when concentrations of the gas peaked some 275 million years ago.

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[Romanus]

That's really cool. Charcoal seems to be incredibly stable; on the "Oceans of Kansas" website, the webmaster shows examples of nearly unaltered late Cretaceous charcoal, preserved in limestone.