Two StFX researchers, Dr. Donnelly Archibald and Dr. Brendan Murphy, are part of a new study published in the journal Geology that has revealed how massive ancient glaciers acted like giant bulldozers, reshaping Earth's surface and paving the way for complex life to flourish.
The full study, titled The Neoproterozoic Glacial Broom,' is a collaboration between Curtin University, St. Francis Xavier University, and the University of Portsmouth.
L-r, Dr. Donnelly Archibald and Dr. Brendan Murphy
Chemically analyzing crystals in ancient rocks, the researchers discovered that as glaciers carved through the landscape, they scraped deep into the Earth's crust, releasing key minerals that altered ocean chemistry.
This process had a profound impact on our planet's composition, creating conditions that allowed complex life to evolve.
"Our study focused on a crucial time in Earth's evolution, some 600 million years ago, when the Earth was so cold, the oceans froze all the way to the equator," Dr. Murphy says.
"At that time, no life existed on land, it only existed in the oceans and on continental shelves. The atmosphere had no source of water, so the water cycle that kids learn about at school was shut off. But beneath the ice, in the deep oceans, geological processes, including volcanic activity, sustained life by pumping essential nutrients of life into the oceans. If that didn't happen, we would not exist!"
Dr. Archibald says about 600 million years ago, glaciers scoured the continents, grinding surface rock into fine sediment. "When the climate warmed and the glaciers melted, all this sediment was rapidly transported into the oceans. Some of this sediment carried essential nutrients to the oceans and fundamentally changed ocean chemistry and oxygen levels in the atmosphere, which may have stimulated the evolution of multicellular life."
Lead author, Professor Chris Kirkland from the Timescales of Mineral Systems Group within Curtin's Frontier Institute for Geoscience Solutions, said the study provides valuable insights into how Earth's natural systems are deeply interconnected.
"When these giant ice sheets melted, they triggered enormous floods that flushed minerals and their chemicals, including uranium, into the oceans," Professor Kirkland said.
"This influx of elements changed ocean chemistry, at a time when more complex life was starting to evolve.
"This study highlights how Earth's land, oceans, atmosphere and climate are intimately connected-where even ancient glacial activity set off chemical chain reactions that reshaped the planet."
Professor Kirkland said the study also offered a new perspective on modern climate change, showing how past shifts in Earth's climate triggered large-scale environmental transformations.
"This research is a stark reminder that while Earth itself will endure, the conditions that make it habitable can change dramatically," Professor Kirkland said.
"These ancient climate shifts demonstrate that environmental changes, whether natural or human-driven, have profound and lasting impacts.
"Understanding these past events can help us better predict how today's climate changes might reshape our world."
