Unique water features (IMAGE) Brown University Caption Raised ridges spidering across the floor of a Martian crater were likely created by runoff from a long-lost glacier that once draped the planet's southern highlands. Credit NASA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.