Geologists Discover Prehistoric River Under Antarctic Ice Sheet

By: Sam Watanuki | Published: Jun 25, 2024

In an exciting revelation, geologists have uncovered the remnants of an ancient river system beneath the West Antarctic ice sheet.

This prehistoric river once flowed for nearly a thousand miles, offering a fascinating glimpse into Earth’s distant past.

Journey Through Time

The river system dates back to the middle-to-late Eocene epoch, around 34 to 44 million years ago.

drop falling into water

Source: Freepik

During this period, Earth experienced significant climate changes, transitioning from an ice-free world to one dominated by glaciers.

A River's Path

The ancient river traversed approximately 930 miles (1,500 kilometers) across Antarctica.

Water seen around large icebergs and mountains in Antarctica in the daytime.

Source: henrique setim/Unsplash

This vast river system eventually drained into the Amundsen Sea, carving a path through what is now a frozen landscape.

Uncovering Sediments

Geologists led by the study’s co-author and sedimentologist, Johann Klages, embarked on a 2017 expedition aboard the research vessel Polarstern.

Light shines on the bottom of an area of water.

Source: Yannis Papanastasopulos/Unsplash

Their mission: to drill into the seafloor and retrieve sediment cores that could reveal clues about Earth’s climatic history.

Sediment Secrets

By analyzing the sediments, the team discovered layers from two distinct periods.

Male scientists analyzing a sample under a microscope

Source: Freepik

The lower sediment layer, dating back to the mid-Cretaceous period, contained fossils of a temperate rainforest, indicating a much warmer climate.

Evidence of a Delta

The upper sediment layer, from the Eocene epoch, showed patterns resembling a river delta.

A steamboat seen on the Mississippi River in the daytime.

Source: Tomas Martinez/Unsplash

This finding was similar to deltas seen in major rivers like the Mississippi and Rio Grande, suggesting a significant ancient waterway.


Biomarker Analysis

To confirm their suspicions, the scientists conducted a lipid biomarker analysis.

A picture of two scientists seated together in their laboratory

Source: Freepik

They found unique molecules from freshwater cyanobacteria, which lived in the ancient river, further supporting the existence of this prehistoric river system.


Climatic Implications

The discovery provides crucial insights into past climate events.

A blue seawater seen underneath a clear blue sky.

Source: Sarah Brown/Unsplash

The Eocene epoch had carbon dioxide levels almost double those of today, similar to what we might expect in the next 150 to 200 years if greenhouse gas emissions continue to rise.


Learning from the Past

Johann Klages emphasized the importance of learning from Earth’s history, stating, “If we think about potentially severe climate change in the future, we need to learn from periods in Earth’s history where this already happened.”

Some melting ice in the middle of a lake. Mountains are in the background, and snow is on top.

Source: Melissa Bradley/Unsplash

“This is exciting — just having this exciting image in your brain that there was this gigantic river system flowing through Antarctica that is now covered by kilometers of ice.”


Future Research

The team is now examining sediments from the Oligocene-Miocene period, about 23 million years ago.

A researcher is pictured at his desk working on an idea

Source: Wikimedia

These findings will help refine climate models, improving our understanding of future climate scenarios.


Challenges of Exploration

Exploring West Antarctica is no easy task. Most of the region is covered in thick ice, making it difficult to access sedimentary rocks.

A mountain in Antarctica covered in snow and ice, slightly hidden by clouds and a hazy, grey sky.

Source: Michelle Raponi/Pixabay

Despite these challenges, the 2017 expedition successfully retrieved valuable samples.


A Glimpse into Earth's History

This discovery not only sheds light on Antarctica’s past but also highlights the planet’s climatic volatility.

A close-up view of massive ice glacier mountains in Antarctica.

Source: Torsten Dederichs/Unsplash

Understanding how Earth responded to past climate changes can guide us in addressing current and future environmental challenges.