Ancient Oceans on Mars May Have Been Older and Shallower Than Thought

[Judi Lynn]

By Charles Q. Choi, Space.com Contributor | March 19, 2018 01:08pm ET

The rise of the largest volcanoes in the solar system may have led Mars to possess oceans hundreds of millions of years earlier than previously thought, a new study finds.

Although Mars is now cold and dry, there is widespread evidence that oceans once covered much of the Red Planet's surface. However, there are scientists who hotly debate this idea, arguing that there are plenty of signs against Mars once having seas.

For example, previous research found signs of ancient shorelines lining the northern plains of Mars for thousands of miles. However, skeptics point out that shorelines generally trace a mostly constant sea-level surface. In contrast, these Martian features are very irregular, "varying in elevation by up to several kilometers," study lead author Robert Citron, a planetary scientist at the University of California, Berkeley, told Space.com. [The Search for Water on Mars in Photos]

Previous research has suggested the variations in these shorelines might have occurred after the formation of Tharsis, a region 3,000 miles (4,800 kilometers) wide that holds the biggest volcanoes in the solar system. The creation of a "volcanic province" with the mass of Tharsis could have shifted the axis on which Mars spins, potentially explaining shoreline elevation variations.

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