Hidden beneath the thick ice sheet of East Antarctica, a team of researchers has uncovered the remnants of vast prehistoric river landscapes. These ancient, river-carved plains, preserved for millions of years, offer new insights into Earth’s distant past and could provide a clearer understanding of how Antarctica’s ice sheets may evolve in the future.
Ancient River Systems Beneath East Antarctica
A team of researchers from Durham University has studied radar data across a 3,500 km (2,175 miles) stretch of East Antarctica, from Princess Elizabeth Land to George V Land. Their investigation led to the discovery of 31 flat surfaces beneath the East Antarctic Ice Sheet (EAIS). These surfaces, preserved under ice that reaches thicknesses of up to 2,500 meters (8,200 feet), appear as gently sloping plains, which were once part of an extensive river landscape. This vast fluvial system developed after East Antarctica separated from Australia millions of years ago.
The researchers used data from four major airborne surveys to analyze the landscape in detail. The results revealed large, low-relief plains that dip seaward and are clustered around elevations of 200 to 450 meters (656 to 1,476 feet) above current sea levels, adjusted for ice unloading. These features are strikingly similar to river-carved landscapes along the Australian coast, formed through similar natural processes.
Surviving for Millions of Years
Despite the passage of over 30 million years, these ancient plains have survived largely intact beneath the ice. Unlike most landforms that were likely destroyed by glacial erosion, the surfaces of these plains were largely shielded by a layer of frozen ice at the base. Deep glacial troughs carved by fast-moving ice separate the plains, but the features themselves remained mostly unaffected by glacial erosion.
Fast-moving glaciers like Totten and Denman, which flow through these deeper troughs, highlight the stark contrast between the slow-moving, cold-based ice above the flat plains. This has allowed the ancient features to remain intact.
Key Findings and Impact on Ice Flow Predictions
The study’s findings hold significant implications for understanding the future of Antarctica’s ice sheets. As Dr. Guy Paxman, one of the lead researchers, explains, “Information such as the shape and geology of the newly mapped surfaces will help improve our understanding of how ice flows at the edge of East Antarctica.”
The ancient river plains are not only remnants of the past but also play a role in shaping the ice flow dynamics of today. The ice above these plains moves slower compared to the fast-flowing glaciers that carve through the deeper troughs. These features could potentially anchor ice during future warming events, providing stability to the ice sheet. As a result, they may slow the retreat of grounding lines, which could help reduce ice loss into the ocean and slow the rate of sea-level rise.
The Road Ahead for Ice Sheet Modeling
Current ice sheet models often overlook these hidden features due to their limited resolution. As the study points out, a more detailed understanding of the topography beneath the ice could improve projections for how East Antarctica’s ice sheet will behave under different levels of climate warming.
This underscores the need for more advanced drilling and high-resolution modeling to fully capture how these ancient river systems influence the grounding lines and the movement of ice.
The East Antarctic Ice Sheet holds about 90 percent of Antarctica’s ice, and if it were to melt entirely, it could raise sea levels by as much as 52 meters (171 feet). Understanding the dynamics of this massive ice sheet is vital for more accurate sea-level rise projections.
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