The discovery of lay minerals point to the existence of a wet environment "at thousands of sites" in the southern region of Mars, an area where rocks date back approximately four billion years old, according to a report from NASA's Jet Propulsion Lab. The discovery was first reported this week in the journal Science.
"We can now say that the planet was altered on a global scale by liquid water about four billion years ago," said John Carter of the University of Paris, the report's lead author.
Scientists are now attempting to place when the wet environments prevailed compared with other important steps in the planet's early history. The northern part of the planet has a lower elevation than the southern part and scientists believe that disparity was the result of a giant meteor impact. The formation of "water-related minerals" most likely to foster conditions for likely occurred between the time of the giant impact and the period when younger sediments created a covering mantle on the planet's surface.
"That large impact would have eliminated any evidence for the surface environment in the north that preceded the impact," Scott Murchie of Johns Hopkins University, who co-authored the report. "It must have happened well before the end of the wet period."