PUZZLING Martian gullies, thought to have been carved by flash floods, may actually be patterns formed by “rivers” of dust particles.
In 2000, the Mars Global Surveyor photographed several features that look a lot like terrestrial gullies cut into the soil by water. There are no impact craters near these gullies, implying that these features are less than a million years old. But Mars has been colder than a Siberian winter for most of its life, so any water would have been rock hard.
To explain these gullies, Mike Malin of Malin Space Science Systems in San Diego, California, who…
