Scientists have discovered that the meteorite that wiped out Earth’s dinosaurs instantly ignited forest wildfires thousands of kilometers away from its impact zone.
At the end of the Cretaceous Period 66 million years ago, a six-mile-wide meteorite struck the Yucatan peninsula in what is now Mexico, causing a mass extinction that killed off more than 75% of living species.
Uncertainty and debate have surrounded the circumstances surrounding the devastating wildfires caused by the strike, with several theories as to how and when they began, as well as their full extent.
A team of geoscientists from the UK, Mexico, and Brazil recently discovered that some of the fires broke out within minutes, at most, of the impact, in areas stretching up to 2500 km or more from the impact crater, by analysing rocks dating to the time of the strike.
The backwash from the mega-tsunami caused by the impact swept charred trees offshore, putting an end to coastal wildfires.
Geoscientists discovered that fires had already started when the trees were washed away soon after the initial impact by studying the fossilised tree bark.They concluded that this was caused by either a massive fireball or heat from droplets of melted rock falling back through the atmosphere in the immediate aftermath of impact.
Professor Ben Kneller of the University of Aberdeen’s School of Geosciences is one of the study’s co-authors, along with researchers from the Autonomous University of Mexico, the Federal University of Rio Grande do Sul, the University of Leeds, and the University of Manchester. The findings were reported in the journal Scientific Reports.
According to Professor Kneller, “what triggered these forest wildfires, as well as their extent and timing, have been debated for quite some time.”
“It was unclear until now whether the fires were caused directly by the impact or indirectly, as vegetation killed by the post-impact darkness caused by debris thrown up into the atmosphere was set ablaze by things like lightning strikes.”
“By assembling this international team, we were able to use a unique combination of chemical, isotopic, paleontological, palaeobotanic, chemical, and spectroscopic techniques, as well as geological mapping, to first confirm that the rocks we analysed were impacted precisely.”
“Then, to determine the extent of the burning, we examined fossilised bark still attached to the tree trunks, discovering that the bark was already charred as the trees were washed away by the impact-related tsunami. This indicates that the fires must have started within minutes, if not seconds, of impact.”
“Ultimately, our research confirms how and when these devastating fires started, and it paints a vivid and terrifying picture of what happened in the immediate aftermath of the meteorite strike.”
