Study estimates amount of water needed to carve Martian valleys

(Northern Illinois University) A new Northern Illinois University study calculates the amount of water needed to carve the ancient network of valleys on Mars and concludes the planet's surface was once much more watery than previously thought. The study bolsters the idea that Mars had a warmer climate and active hydrologic cycle, with water evaporating from an ancient ocean, returning to the surface as rainfall and eroding the extensive network of valleys.