International Spotlight Shines on Colby Geologists

Natural Sciences4 MIN READ

A new research paper about the origins of wildfires also tells us about the earliest forms of life on Earth

Colby geology research associate and paleobotanist Ian Glasspool spoke with the BBC World Service about his latest research on wildfires. Glasspool and Robert Gastaldo, the Whipple-Coddington Professor of Geology, Emeritus, coauthored a landmark paper dating the earliest wildfires to 430 million years ago.
By Bob KeyesPhotography by Jasper Lowe
July 7, 2022

Two Colby geology professors are receiving international attention for research that concludes the earliest wildfires began burning about 430 million years ago, or 10 million years earlier than previously known.

“Wildfires are in the news in a big way,” said Ian Glasspool, a research associate in Colby’s Geology Department and coauthor of the paper with Robert Gastaldo, the Whipple-Coddington Professor of Geology, Emeritus. “They’re on everybody’s mind not just here in the States, but across the world.”

Geology magazine, a journal of the Geological Society of America, published their paper in mid-June. Since then, their research has received attention in the science press and media outlets in India, Japan, Russia, and elsewhere. Among the interviews Glasspool has given was one with the BBC World Service, which featured him on its Science-in-Action podcast.

Science News,, and Sputnik International also have covered the story. The attention is gratifying, the professors said. “Any time you get picked up by the BBC, you get an immediate international audience,” said Glasspool, who originally hails from the UK but is now a U.S. citizen. “It’s not just a scientific audience, but a very diverse general audience. It’s a huge success for what we are doing here at Colby.”

Colby News reported on their findings last winter, before they finished their paper.

The ability of Glasspool and Gastaldo to date wildfires has generated the headlines, but a significant element of their research is what the presence of that fire means—that atmospheric oxygen levels were higher many millions of years ago than previously known, supporting naturally occurring wildfires and life itself.

Fire requires three ingredients: fuel, a source of ignition, and oxygen. The fuel consisted of plant macrofossils—tiny plants that would have grown along the surface of the Earth. The ignition came from lightning, and there was enough oxygen in the atmosphere to produce and sustain wildfires.

“The significance of our research is understanding the parameters that allow terrestrial life to occur,” said Glasspool, a paleobotanist. “The presence of wildfires indicates an oxygenated atmosphere at levels that would have permitted animal life to dwell on land, just as we experience the world today.”

Gastaldo explained it more directly. “Breathe in, breathe out,” he said. “The concentration of oxygen that we have now is why we are living, and that concentration has not been there over the course of the planet’s history.”

Thanks to the Colby scientists, we now know that both wildfire and evidence of animal life, in the form of charcoalified fecal pellets, was there 430 million years ago. Without sufficient levels of oxygen, animal life on earth could not have evolved.

Today, oxygen accounts for about 21 percent of the gasses in the atmosphere. Based on their research, Glasspool and Gastaldo concluded the ancient atmosphere contained at least 16 percent oxygen, which is the minimum percentage of oxygen required for a wildfire to spread.

With the support of National Science Foundation grants, the Colby scientists have spent many years studying early terrestrial ecosystems to determine wildfire activity over time. Their research has led them to fossils entombed as charcoal from the Silurian geologic period, which dates from about 440 to 416 million years ago.

Gastaldo described their research as akin to a crime-scene investigation. It’s about collecting evidence, analyzing it, and determining how it fits together, and what it means.

The dark, roughly cubic fragments on this rock are fossil charcoal chunks of an extinct enigmatic organism known as Prototaxites that grew to as much as 30 feet in height and up to three feet in diameter. Scientists most commonly consider Prototaxites a basidiomycete fungus.

In examining and analyzing fossils, Glasspool and Gastaldo concluded that plant life during the Silurian geologic period consisted of low-lying plants that spread across the landscape. Most of those plants would have been small in stature, with just a few growing knee-high or waist-high. But the Earth also supported a fungus known as Prototaxites that could have reached 30 feet.

“I am grateful for the National Science Foundation and Colby for giving us the opportunity to conduct this work,” Glasspool said. “We so greatly appreciate that Colby has the vision to see that this work is worthwhile.”