Researchers at the University of Glasgow just made a wild discovery: steel waste is speeding up the process of rock formation—by thousands of years. According to Gizmodo, the team found that industrial byproducts like slag (a waste product from steel production) are hardening into new rocks in just a few decades, not the millions of years it typically takes.

It’s a shift so dramatic that scientists are calling it a “rapid anthropoclastic rock cycle,” a term highlighted in their GeoScienceWorld study.

“When waste material is first deposited, it’s loose and can be moved around as required,” co-author Amanda Owen said in a statement. “What our finding shows is that we don’t have as much time as we thought to find somewhere to put it where it will have minimal impact on the environment–instead, we may have a matter of just decades before it turns into rock, which is much more difficult to manage.”

The researchers confirmed their timeline using clues hidden in the hardened debris—like a ring pull from a soda can and a King George V coin from 1934. Both were found embedded in rocks formed in West Cumbria, England. That aluminum tab dates the formation to sometime after 1989—meaning the rocks formed in as little as 35 years.

“What’s remarkable here is that we’ve found these human-made materials being incorporated into natural systems and becoming lithified–essentially turning into rock–over the course of decades instead,” Owen said. “It challenges our understanding of how a rock is formed, and suggests that the waste material we’ve produced in creating the modern world is going to have an irreversible impact on our future.”

The process happens when slag mixes with seawater and air—a chemical combo that jumpstarts the rock-making process, according to study co-author David Brown.

The team believes this isn’t just a UK thing—similar rock formations may be appearing around the world, thanks to industrial pollution. That matters, Owen warns, because these rocks could start reshaping our coastlines and ecosystems as climate change brings rising seas and harsher storms.

“The rapid appearance of rock could fundamentally affect the ecosystems above and below the water,” she said, “as well as change the way that coastlines respond to the challenges of rising sea levels and more extreme weather as our planet warms.”

The full study is based on analysis of deposits from the Derwent Howe slag bank in West Cumbria.