Imagine trying to study a historical event. The beginning is somewhat known, and the ending is clear. But most of the middle part is missing, and there’s little to explain how the event unfolded from one stage to the next.
For geologists, this has been the maddening experience of studying the bedrock of the Transantarctic Mountains of Antarctica. There’s a gap in their knowledge that stretches for hundreds of millions of years.
However, with the help of a rock library, a recent study has found evidence of what may have happened in these missing millennia.
Missing Millennia
The Transantarctic Mountains (TAM) are a massive mountain belt that spans Antarctica, separating the eastern part of the continent from the west. Most of the continent is covered in ice or seawater, and the uplifted rock on Antarctica is part of the TAM.
The TAM stretches for almost 2,000 miles. The highest peaks soar to elevations of 14,000 feet above sea level. Even though the TAM are remote and difficult to reach, they hold a critical geologic record of the continent and are important to geologists.
Problematically, this record is incomplete.
“We’ve been looking at the young and old history of the continent, and there is a gap in our understanding of what happened in Antarctica between those two time periods,” says Timothy Paulsen, a professor of geology at the University of Wisconsin-Whitewater. “What happened in between isn’t well established.”
And there’s quite an age gap between the young and old history. The old history dates back 500 million years ago. The new history is more like 100 million years ago.
To better understand the missing middle, Paulsen was part of a research team that examined rock samples from the Polar Rock Depository at The Ohio State University’s Byrd Polar and Climate Research Center. The depository has more than 60,000 rock samples from Antarctica and the southern oceans. Scientists are able to peruse the depository’s database and then request samples for analysis.
“We were able to actually use that library of rocks to select samples to then extract the minerals we were analyzing,” Paulsen says.
Analyzing these samples led to a new understanding of what happened during those missing millennia.
Read More: Did an Ancient Civilization Ever Live in Antarctica?
Moving Mountains
In a 2025 study in Earth and Planetary Science Letters, Paulsen and his co-authors revealed a surprising finding. Scientists knew that there had been significant mountain movement around 500 million years ago, but they assumed the middle period was relatively quiet.
“Antarctica was supposed to be really quiet and not much going on until about 150 million years ago when the Transantarctic mountains rose up,” Paulsen says.
But the rock samples the team analyzed showed evidence of cooling events.
“This cooling seems to correlate with erosion, and it also correlates with major changes we see with other parts of Antarctica, [which] suggests there were changes plate tectonically,” Paulsen says.
This means that the quiet period was not so quiet after all. The mountains rose up, stripped the overriding rocks, and then cooled down.
“Instead of being quiet during this time period, Antarctica was pretty dynamic,” Paulsen says.
The study has helped scientists have a better understanding of how the TAM came into their current state. There is much more they would like to know, and Paulsen says the origins of the TAM are debated among geologists.
Piecing together the ancient history of the TAM matters because Paulsen says it helps us understand the mountain belt today.
“What that indicates is there is an older history of the landscape that probably influenced the landscape we see today,” Paulsen says.
Read More: Ancient Wildfires Shaped Antarctica and the Atacama Desert into the Most Extreme Places on Earth
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Emilie Lucchesi has written for some of the country’s largest newspapers, including The New York Times, Chicago Tribune and Los Angeles Times. She holds a bachelor’s degree in journalism from the University of Missouri and an MA from DePaul University. She also holds a Ph.D. in communication from the University of Illinois-Chicago with an emphasis on media framing, message construction and stigma communication. Emilie has authored three nonfiction books. Her third, A Light in the Dark: Surviving More Than Ted Bundy, releases October 3, 2023, from Chicago Review Press and is co-authored with survivor Kathy Kleiner Rubin.
