Scientists have tracked down the oldest wildfires ever discovered thanks to 430-million-year-old charcoal deposits from Wales and Poland. They give us an invaluable insight into what life on Earth was during the Silurian period.
Plant life hampered heavily by water to reproduce and most likely wouldn''t have happened in areas that were dry for about half the year. The wildfires discussed in the study would have burned through very short vegetation, plus the occasional knee- or waist-high plant.
The scientists predicted that the landscape would not be represented by trees, but by the ancient fungus Prototaxites. It''s unlikely that the fungus is known to be capable to grow as high as nine meters (or about 30 feet tall).
One of the samples used in the study is Glasspool et al., Geology, 2022.
"It appears now that our fire evidence is closely related to our evidence of the early land plant macrofossils," says the paleobotanist.
"So as soon as there''s fuel, at least in the form of plant macrofossils, there is pretty much instant wildfire."
Fires need fuel (plants), an ignition source (which here would have been lightning strikes) and enough oxygen to burn.
According to researchers, the possibility that fires were capable of propagating and leaving charcoal deposits suggests that Earth''s atmospheric oxygen levels were at least 16 percent.
Today, the level is 21 percent, but it has dramatically altered in the course of Earth''s history. Based on their findings, the researchers believe that atmospheric oxygen levels 430 million years ago might have been 21 percent or higher.
It''s all fantastic information for paleontologists. A study suggests that increased plant life and photosynthesis would have contributed to the oxygen cycle during these wildfires, and that understanding the details of that oxygen cycle across time gives scientists an idea of how life might have evolved.
"The Silurian landscape required sufficient vegetation across it to prevent wildfires and to maintain a record of that wildfire," says a paleontologist.
"At points in time that we''re sampling windows of, there was enough biomass around to be able to provide us with a record of wildfire that we can identify and exploit to identify the vegetation and process in time."
The landscape that is now Europe was quite different hundreds of millions of years ago, and the two sites that the researchers used for their investigation would have been on the ancient Avalonia and Baltica continents during the time these wildfires raged.
Wildfires would have influenced both carbon and phosphorus cycles, as well as the movement of sediment on the Earth''s surface. It''s a complex combination of things that requires a lot of cleaning.
This discovery certainly aids in decomposing the previous record for the oldest wildfire on record by 10 million years, but it also highlights the importance that wildfire research may have in recharging Earth''s history.
"Wildfire has been an integral component in Earth-system processes for a long time, and its role in these systems has almost certainly been underemphasized," says Glasspool.
Geology has produced this research.