Satellites map nearly 2,000 valleys and buried mountain range beneath Greenland ice

Satellites mapped nearly 2,000 hidden valleys beneath Greenland’s ice, revealing a buried mountain range

Beneath Greenland’s ice sheet — a frozen mass stretching across 650,000 square miles and reaching more than 1,864,000 miles deep — lies an entire landscape no human has ever directly seen. Mountains, valleys, and ancient terrain carved long before most of the ice above them existed have remained locked away, largely beyond reach.

Until now. A newly developed mapping method has produced the most detailed picture yet of this buried world, revealing nearly 2,000 subglacial valleys hidden beneath the ice and raising new questions about what shaped them — and what they mean for the ice sheet’s future.

A map built from shadows on the ice

The technique behind this discovery is called Ice Flow Perturbation Analysis. As ice moves over buried valleys and ridges, the underlying topography leaves faint impressions on the surface above — subtle bumps and dips that satellites can detect in fine detail. Scientists then work backward from those surface signals to infer the shape of the hidden bedrock below.

Researchers used these ghostly imprints to build a new layer of understanding beneath the ice. The work is designed to improve BedMachine Greenland, the existing high-resolution dataset scientists rely on to model the island’s terrain. Their findings were described in a NASA-led paper published in Geophysical Research Letters.

What the new map reveals

Using this method, researchers manually mapped 1,943 subglacial valleys — about a third of which are newly identified. The revision is significant: roughly half the valleys already included in BedMachine Greenland are now known to extend farther inland than previously mapped, in some cases by hundreds of miles.

Near the eastern highlands, the map uncovers something striking — a previously unmapped mountain range buried beneath the ice, complete with interconnected valleys and relief that increases toward the coast. These alpine-style landforms may have survived under the ice since at least the Pliocene epoch, a period ending roughly 2.6 million years ago, preserved in place while the ice sheet grew around and above them.

A geological riddle in the west

Not everything fits neatly into existing models. In the west-central region, many valleys are unusually long, straight, and consistently oriented in a southwest-northeast direction — the kind of alignment that typically points to a tectonic influence, where fractures or fault lines create preferential pathways for water to flow and valleys to form.

That’s unexpected. Greenland has long been treated as a rigid, stable block of ancient rock. “That’s a riddle to us,” said Joe MacGregor, a NASA cryospheric scientist and co-author of the study. Tectonic activity of this kind isn’t something researchers typically associate with the island.

The branching angles add another layer to the puzzle. Wide angles suggest surface water alone didn’t carve these features. Instead, a widespread groundwater network — seeping upward and eroding surrounding rock — likely played a major role long before the ice sheet ever formed above them.

How valleys shape the ice above them

The valleys aren’t passive features. They actively direct how the ice sheet behaves. Ice flow concentrates in valleys, forming glaciers that eventually move toward the coast and calve into fjords — setting off a self-reinforcing cycle where funneled ice grows thicker, thicker ice flows faster, and faster flow carves the valley even deeper over time.

The effect is dramatically visible along western Greenland’s coastline. MacGregor described the glacially incised landscape there as resembling Yosemite’s El Capitan — valley after valley, each one sculpted by the same relentless process. That relationship helps explain why some glaciers are far more dynamic and vulnerable to change than others located nearby.

Why this matters for Greenland’s future

As the ice sheet continues to retreat, flow will keep concentrating wherever valleys already exist. Knowing their precise locations is essential — not just for understanding the present, but for projecting what happens decades out.

Current ice loss models work reasonably well over short timescales. Longer-range forecasts, though — extending beyond the next decade or two — depend heavily on accurate topographic data. The more precisely scientists know where the valleys are and how deep they run, the better they can anticipate how faster ice flow will propagate into Greenland’s interior as warming continues.

“The better we understand the topography now,” MacGregor said, “the better sense we’ll have of what it will look like in the longer term — beyond the next decade or two — as faster ice flow propagates into Greenland’s interior.”

The findings are expected to feed into future, more accurate versions of BedMachine Greenland. Each revision brings scientists closer to a complete picture of what lies beneath the ice — and closer to reliable answers about how much, and how fast, that ice will eventually disappear. For now, nearly 2,000 valleys have stepped out of the dark. The questions they raise are only beginning to be answered.