The surface of Mars, with its dune flows, gullies and slope movements, is the result of sediment being transported downwards in the recent past as well as today. But this “mass wasting”, typically caused by flows of water – for example, how the gullies on Earth are shaped – has proved a mystery to planetary scientists. This is because it is assumed that huge amounts of water are needed to form these features.
The problem is, there is a lack of enough water on Mars now and in the planet’s recent past. In a new study published in
