PACIFIC CITY, Ore. — Scott Burns, professor emeritus in geology at Portland State University, thought he had seen it all — until he saw a couple of photos of an extremely rare sand formation on the ...

The Juventae Chasma on Mars contains dunes of all sizes, from the smallest ripples through the largest draa towering hundreds of meters tall. A giant draa, superimposed with dunes, transverse aeolian ...

This beautiful sandy landform on Mars, called a "draa," was imaged by the HiRISE instrument aboard NASA's Mars Reconnaissance Oribter on on Jan. 6, 2014. (Source: NASA) To my eye, the image above ...