Water carved valleys suggest ancient snowfall on Mars

Washington: A new study has found that water-carved valleys at four different locations on Mars appear to have been caused by runoff from orographic precipitation-snow or rain that falls when moist prevailing winds are pushed upward by mountain ridges. The new findings are the most detailed evidence yet of an orographic effect on ancient Mars and could shed new light on the planet`s early climate and atmosphere. Kat Scanlon, a geological sciences graduate student at Brown, led the research and is well-acquainted with the orographic effect. She did graduate work in meteorology in Hawaii, which is home to a quintessential orographic pattern. Moist tropical winds from the east are pushed upward when they hit the mountains of Hawaii`s big island. The winds lack the kinetic energy to reach the mountain summit, so they dump their moisture on the eastern side of the island, making parts of it a tropical jungle. The western side, in contrast, is nearly a desert because it sits in a rain shadow cast by the mountain peak. Scanlon thought similar orographic patterns might have been at play on early Mars and that the valley networks might be an indicator. The researchers, including Jim Head, professor of geological sciences, started by identifying four locations where valley networks were found along tall mountain ridges or raised crater rims. With the knowledge from this study that precipitation was important in carving the valleys, the answers to those additional questions could provide important insight into the climate on Mars billions of years ago. The study is published online in Geophysical Research Letters. ANI