Caltech researchers have identified geological features on Mars that could point to the existence of a long-dried ocean that once covered a third of the Red Planet's surface. The research was conducted by former Caltech postdoctoral scholar Abdallah Zaki and Caltech professor of geology Michael Lamb . The study is described in a paper appearing in the journal Nature on April 15. As a key ingredient for life, water on other bodies in the solar system is a major area of study. While it is widely accepted that Mars once had some amount of liquid water on its surface, it is still unclear whether that water was limited to lakes and streams, or if there was enough to form long-lasting oceans. Past Mars missions have discovered geologic features that look like shorelines, but they are subtle and are found at varying elevations across the planet.…