A New Type of Dune Has Been Found on Mars Called “wind-drag ripples,” these novel formations are an intermediary between two rippled structures found on our own planet — large desert dunes and tiny, decimeter-scale sand waves. With crest-to-crest wavelengths measuring in the meters, wind-drag ripples are unlike anything observed on Earth, or elsewhere. June 30, 2016 at 05:15PM via Digg