Martian gullies likely not formed by water: NASA
New findings from NASA's Mars Reconnaissance Orbiter revealed that the Martian "gullies" were likely not formed by flowing water. It was believed that the formation of these "gullies" was similar to those on Earth. The findings showed no mineralogical evidence for abundant liquid water or its by-products, pointing to other mechanisms possibly the freezing and thawing of carbon dioxide frost.