The white glass blends in with quartzite samples in the area, making them a challenge to pick out. White Darwin glass fragments make up less than 3 percent of all finds. The authors suggest that, in less well-preserved fields, the tiny fraction of white glass could easily remain undiscovered.
Howard and his team weren't originally looking for organics. But when they examined the glass, they found surprising evidence of crystalline quartz.
"I went looking for crystals in the glass, only to discover the spherical inclusions," Howard said.
Inside the tiny crystal pockets, spheres up to 200 micrometers in diameter contained organics including cellulose, lignin, aliphatic biopolymer, and protein. The signature from the biomarkers suggested that fragments of peat were trapped in the molten glass, rapidly heating and degassing to create a frothy, bubble-like texture.
Trapped inside of glass, the organics would have been prevented from breaking down via oxidation. Howard's samples showed no signs of fossilizations, indicating that such trapped organics could last as long as the glass around them.
"Providing the glass seal isn't broken, it's a good preservation method," said organic geochemist Stephen Bowden at the University of Aberdeen in Scotland. Bowden, who was not involved in the research, has previously studied fossil organic matter within impact rocks and its survival during atmosphere re-entry.
"[It's] like setting something in resin or amber — like a scorpion novelty in a glass paperweight."
Fossil organic matter — fossil fuels — have been found in rocks formed by meteorite impacts and glasses from experimental collisions, but never before organics with such a well-preserved biological character
The research was published in the journal Nature Geoscience on November 10.
Finding organics inside of glass could have extensive ramifications. Though Howard found glass spheres that crashed back to Earth, other spheres could have been hurled into space, if their velocities were high enough.
"Survival in or transfer to ejecta is a 'big deal' because of the conditions of its formation — it's surprising — and the fact that it can leave Earth's atmosphere," Bowden said. (7 Theories on the Origin of Life)