A NASA-led research team has mapped 1,943 valleys buried beneath the Greenland Ice Sheet, identifying previously unknown geological features and showing that known channels reach much farther inland than previously recorded.
The study, published in Geophysical Research Letters, used Ice Flow Perturbation Analysis to trace channels hidden under an ice sheet spanning 1.7 million square kilometres (656,000 square miles) and measuring more than 3 kilometres (1.9 miles) at its thickest point. About a third of the 1,943 mapped valleys are newly identified.
Valleys Reach Deeper Inland
About half of the valleys included in BedMachine Greenland extend farther inland than previously indicated, in some cases by hundreds of kilometres.
The geometry of the network offers clues about the ancient landscape before glaciation. Relatively wide branching angles of the valleys suggest a widespread groundwater network helped carve them before the ice sheet formed.
In the west-central region, researchers found long, straight valleys aligned consistently in a southwest-northeast direction, suggesting a tectonic influence. "That’s a riddle to us," said study co-author Joe MacGregor, a NASA cryospheric scientist. "Greenland is justifiably usually treated as a rigid block of old rock that is simply translated as needed to accommodate the motion and interactions of other tectonic plates."
Buried Mountain Range
Near the eastern highlands, the mapping revealed an alpine-style mountain range beneath the ice. MacGregor described the relief as "El Capitan after El Capitan," noting that the peaks may have survived under the ice since at least the Pliocene.
According to MacGregor, improving knowledge of the bed topography gives scientists a clearer view of long-term conditions over the coming decades as faster ice flow extends deeper into Greenland's interior.
