Mars valleys may have been formed by melting glaciers

Was ancient Mars covered in glaciers, whose melting carved out its distinctive valleys?

Scientists have found similarities in the shapes of channels created on Mars (right) and those formed by glacier meltwater in Earth’s Arctic region (left). Credit: Cal-Tech CTX mosaic and MAXAR/Esri

A fresh look at Martian valleys has found they may have been created by melting glaciers, not free flowing rivers as previously thought.

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For years, scientists assumed that several Martian channels and valleys were created by flowing rivers, and that early Mars was much warmer and wetter than it is today.

But when planetary geologist Anna Grau Galofre from Arizona State University studied the features, she saw a striking resemblance to formations found in the Arctic created by water draining away from the underside of a glacier.

Valles Marineris on Mars is the largest canyon in the Solar System, extending over 3,000km. It is as much as 600km wide and as much as 8km deep. Credit: NASA
Valles Marineris on Mars is the largest canyon in the Solar System, extending over 3,000km. It is as much as 600km wide and as much as 8km deep. Credit: NASA

After comparing 10,000 images of Martian valleys to terrestrial counterparts, Grau Galofre’s team found that only a fraction look like they were caused by free-flowing surface rivers, suggesting ancient Mars was not warm and wet, but covered in a great ice sheet.

“We tried to put everything together and bring up a hypothesis that hadn’t really been considered: that channel and valley networks can form under ice sheets, as part of the drainage system that forms naturally under the ice sheet when there’s water accumulated at the base,” says Grau Galofre.

Read the full story at the Arizona State University website.

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Ezzy Pearson is BBC Sky at Night Magazine’s News Editor.