Just like Earth, Mars has vast expanses of rippled sand, but thanks to the tireless work of NASA’s rover Curiosity, a new type of them has been discovered.

Just like Earth, Mars has vast expanses of rippled sand, but thanks to the tireless work of NASA’s rover Curiosity, a new type of them has been discovered. 
Said Mathieu Lapotre, one of the collaborators for the Curiosity mission, “Earth and Mars both have big sand dunes and small sand ripples, but on Mars, there's something in between that we don't have on Earth." 
Such land formations, called impact ripples, generally occur as wind blows particles across the land, causing them to collide with one another and form peaks and rifts. 
However, Lapotre noted, “As Curiosity was approaching the Bagnold Dunes, we started seeing that the crest lines of the…ripples are sinuous. That is not like impact ripples, but it is just like sand ripples that form under moving water on Earth.” 
That suggests Mars once had a much thicker atmosphere, and ripples hailing back to that time may provide insights into how it thinned over the eons.