Professor O’Neil is devoted to understanding the mysteries of the early Earth’s formative years through studying the formation, structure, chemistry and dating of rocks. His research focuses on the Hadean (4.6– 4.0 billion years ago) and Archean (4.0–2.5 billion years ago) eons — periods that shaped the planet’s crust and early environment.
His team studies ancient rocks found near the community of Inukjuak, in Nunavik. Believed to be around 4.3 billion years old, these rocks act as time capsules, preserving evidence of how the first crust on our planet formed and offering rare clues about the tectonic environment at the time. Since some of them likely formed at the bottom of an early ocean, they may even contain insights into Earth’s primordial water reserves and provide a window into how and when life started on Earth. “It’s like looking at the DNA of a rock,” explains O’Neil. “This helps us build a clearer picture of what the Earth looked like and the processes that formed its crust.”
To study and date these ancient samples, O’Neil uses an extinct radioactive decay system instead of the more conventional uranium–lead dating method that’s typically used for old rocks. “Uranium–lead dating works well for rocks that contain specific minerals like zircon,” he explains. “But the challenge with the rocks we’re studying is that they don’t contain these minerals.” These advanced techniques allow his team to explore the deep past and uncover insights into the Earth’s earliest geological processes. “Rocks act like books, with each layer a chapter in the history of our planet,” he says.
Quebec’s ancient past was brought to life in La préhistoire du Québec, a 10-episode docuseries hosted by science educator Patrick Couture. After writing a children’s book series on Quebec’s prehistory, Couture worked with Savoir média to adapt his books for television. The series explores topics ranging from the planet’s formation to the arrival of the first humans in Quebec, highlighting extraordinary creatures and dramatic events that shaped the land.
The series’ first episode, “La naissance du territoire,” features footage filmed at the University of Ottawa and on location in Nunavik. Couture visits O’Neil’s lab to explore how the ancient rocks under study — fragments of the primordial crust — reveal key insights into the early Earth. The episode also touches on emerging evidence of ancient microbial life, suggesting that life may have appeared earlier than previously believed and been preserved in Nunavik’s rocks.
“The airing of each episode sparked a significant interest in geology,” says O’Neil. “Many people reached out with questions and a desire to learn more. This kind of public engagement is essential. Outreach helps people understand why our research matters. It transforms complex scientific ideas into compelling stories, without distorting the facts, and inspires curiosity across a wide audience.” The series was released online in spring 2023 and premiered on Télé‑Québec in April 2025.
The research team is deeply grateful to the Inuit community of Inukjuak for their invaluable support and for granting access to their land — an essential part of the research. This work wouldn’t have been possible without their trust and assistance, highlighting the importance of respectful and collaborative relationships in scientific exploration.
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