Greenland: Scientists have created a new and highly detailed picture of the landscape hidden beneath Greenland’s massive ice sheet, identifying 1,943 subglacial valleys and revealing that many previously mapped valleys extend much farther inland than earlier estimates suggested. The NASA-highlighted research was published in Geophysical Research Letters.

A Landscape Hidden Beneath Kilometres of Ice

Greenland’s ice sheet covers roughly 1.7 million square kilometres and reaches more than three kilometres in thickness at its deepest points.

Beneath that ice lies an extensive bedrock landscape containing mountains, valleys and other geological structures. Scientists cannot directly observe most of this terrain, so they rely on measurements of the ice surface and other geophysical data to reconstruct what lies underneath.

Nearly One-Third of Valleys Newly Identified

Researchers manually mapped 1,943 valleys beneath the ice sheet using a technique called Ice Flow Perturbation Analysis.

About one-third of the mapped valleys had not previously been identified. The analysis also showed that around half of the valleys already included in the BedMachine Greenland dataset may extend hundreds of kilometres farther inland than previously mapped.

Satellites Help Reveal the Hidden Terrain

The new technique takes advantage of the way ice responds to the terrain beneath it.

When flowing ice passes over a buried valley or ridge, the underlying topography can produce extremely subtle changes in the ice surface. Satellite measurements can detect these variations, allowing scientists to work backward and estimate the shape of the hidden bedrock.

The findings are expected to help improve future versions of BedMachine Greenland, a detailed dataset of Greenland’s subglacial terrain.

Ancient Valleys Tell a Geological Story

The newly mapped landscape also provides clues about Greenland’s geological past.

Many valleys appear to originate around the southern and eastern highlands, areas that researchers believe played an important role in the early development of Greenland’s ice sheet.

Scientists also identified a buried mountain range in eastern Greenland surrounded by interconnected valleys. Some of these alpine-style features may have survived beneath the ice since at least the Pliocene, more than five million years ago.

Some Features Remain a Mystery

Not every feature identified by the research fits existing explanations of Greenland’s geological history.

In particular, researchers found numerous long, relatively straight valleys in west-central Greenland that run in a broadly southwest-to-northeast direction.

Their alignment could indicate that tectonic structures influenced where water flowed and where valleys developed, although scientists say the exact explanation remains uncertain.

Groundwater May Have Helped Carve the Valleys

The researchers also examined the way the valleys branch.

Their relatively wide branching patterns suggest that surface water alone may not explain their formation. A widespread groundwater system could have contributed to erosion by moving upward through the bedrock and helping carve the ancient valleys before the modern ice sheet developed.

Why the Hidden Valleys Matter Today

The valleys are not simply remnants of Greenland’s ancient past. They continue to influence how ice moves across the island.

Ice tends to concentrate within existing valleys, creating pathways through which glaciers can flow toward Greenland’s coast. Understanding these pathways can therefore help scientists study how the ice sheet may behave as environmental conditions change.

Improving Future Ice-Sheet Research

Researchers expect the new map to improve understanding of the relationship between Greenland’s underlying geology and the movement of its ice.

As the ice sheet changes, knowledge of buried valleys could help scientists better model how changes near Greenland’s edges may influence ice movement farther inland over longer periods.

The research therefore provides both a new window into Greenland’s geological history and additional information for understanding the future behaviour of its ice sheet.