Greenland’s Hidden Valleys Emerge from Tiny Changes on the Ice
ice sheet
A very large layer of ice covering land.
subglacial valley
A valley in the ground beneath an ice sheet.
Ice Flow Perturbation Analysis
A method that infers hidden ground from small changes in moving ice.
What happened
NASA Earth Observatory, a NASA service that studies Earth, reported a new map of Greenland’s hidden bedrock. The map links valleys beneath the Greenland Ice Sheet that older maps missed or left disconnected. Greenland’s ice sheet covers about 1.7 million square kilometers. Its thickest ice exceeds 3 kilometers. No one has directly seen most of the ground below it. The new map reads that hidden landscape through small changes on the ice surface. NASA Earth Observatory report
How the hidden map was made
Ice flowing over a valley or ridge leaves a faint signature on the surface. Satellites can measure small changes in surface height and ice movement. Scientists used those measurements to infer the shape below. They call the method Ice Flow Perturbation Analysis.
This is not a direct photograph of the bedrock. It is a reconstruction based on clues from the moving ice. That matters because radar surveys do not cover every part of Greenland equally. The new method can add detail across sparsely measured interior areas.
What the new map shows
Researchers manually mapped 1,943 subglacial valleys. About one-third were newly identified. About half of the valleys already included in older maps now appear to extend farther inland. Some continue for hundreds of kilometers beyond their earlier mapped ends.
Many valleys seem to begin in Greenland’s southern and eastern highlands. That pattern fits the idea that the ice sheet began forming there. The map also reveals a mountain range under eastern Greenland. Some alpine-looking landforms may have survived beneath the ice since before the current ice sheet formed.
Other features are harder to explain. Many valleys in west-central Greenland are long, straight, and aligned southwest to northeast. That direction may reflect old tectonic forces in the rock. The researchers describe this pattern as a puzzle. Wide branching angles also suggest that groundwater may have helped carve the valleys before the ice sheet formed.
Why the valleys matter
Ice flow tends to concentrate inside valleys. Ice can become thicker there, and thicker ice can move faster. Faster flow can carve the valley deeper. This creates a feedback that links ancient landforms with modern ice movement.
The map may also improve longer-term forecasts. If Greenland’s ice sheet retreats, researchers expect flow to keep concentrating along existing valleys. A better view of the bedrock could therefore improve projections beyond the next decade or two. It does not provide a precise timetable. It shows where the landscape may guide future flow.
What remains uncertain
The valleys were inferred from surface signals, not seen directly. Every part of the map may not be equally certain. Scientists also do not yet know exactly when each valley formed. The roles of groundwater, ancient tectonic forces, and later glacial erosion remain open questions. The straight valleys in west-central Greenland need further explanation.
What to watch next
NASA says the work can improve future versions of Greenland’s bedrock maps. Researchers will likely compare the inferred valleys with additional radar and other observations. The key test will be whether the new map changes calculations of where ice moves, thickens, and reaches the coast.
Source: NASA Earth Observatory
A new map finds valleys beneath Greenland’s ice
📰 Full story: Greenland’s Hidden Valleys Emerge from Tiny Changes on the Ice
Scientists used tiny surface changes to map hidden ground below Greenland.
ice sheet
A huge layer of ice covering land.
subglacial valley
A valley hidden beneath an ice sheet.
Ice Flow Perturbation Analysis
A method using ice-surface changes to estimate the ground below.
💡 The gist
- NASA mapped valleys under Greenland’s huge ice sheet.
- Satellites measured tiny changes on the ice surface.
- The map may improve forecasts of future ice movement.
An ice sheet is a huge layer of ice covering land. Greenland’s ice sheet covers about 1.7 million square kilometers. Its thickest ice exceeds 3 kilometers. People cannot see the bedrock beneath it directly.
Ice moving over a hidden valley can make a tiny surface change. Satellites measure the ice surface and its movement. Scientists use those measurements as clues. They call this method Ice Flow Perturbation Analysis.
The new map includes 1,943 subglacial valleys. About one-third were not on earlier maps. About half of the older mapped valleys reach farther inland than scientists knew. Some extend hundreds of kilometers farther.
Many valleys seem to start in southern or eastern highlands. This may show where Greenland’s ice sheet began forming. West-central Greenland has another puzzle. Many valleys there are long and straight. They point from southwest to northeast.
Old movement in the rock may have influenced that direction. Groundwater may also have helped cut the valleys. Scientists present these ideas as possibilities, not final answers.
The valleys matter because ice often follows them. Ice can become thicker in a valley. Thicker ice can flow faster. Faster ice can deepen the valley. This link can shape future movement as Greenland’s ice retreats.
The map is still an estimate. It is not a direct picture of every valley. Scientists still need to test the map with other observations. Future maps may help improve long-term ice forecasts.
Source: NASA Earth Observatory
Valleys are hiding under Greenland’s ice
📰 Full story: Greenland’s Hidden Valleys Emerge from Tiny Changes on the Ice
Scientists found hidden valleys by watching tiny changes in the ice.
ice sheet
Thick ice covering a wide piece of land.
satellite
A machine that watches Earth from space.
valley
A low place between higher ground.
NASA, the U.S. space agency, studied Greenland.
Greenland has a giant ice sheet. An ice sheet is thick ice covering land.
People cannot look through this ice. Under it, the ground has many valleys.
NASA used satellites to watch the ice surface. A satellite is a machine that watches Earth from space.
Ice moving over a valley can make a tiny change. Scientists used those changes as clues.
Then they drew a map underneath. Some valleys were already known. Some valleys were new on the map. Other valleys reached farther inland.
Valleys can guide moving ice. When ice gathers there, it can move faster. This helps scientists think about future ice movement.
Scientists still have questions. They have not seen every valley directly. They also do not know every valley’s age.
Source: NASA Earth Observatory