Did Mars once have oceans? That is one of the oldest and most-debated questions about the Red Planet; the evidence has been tantalizing but also inconclusive so far. Now, two new studies are suggesting that indeed there was a large ocean in the northern hemisphere a long time ago.
The first study focuses on polygonal terrain similar to that seen on ocean bottoms here on Earth, while the second suggests that the largest Martian volcano, Olympus Mons, was surrounded by that ocean, much like the Hawaiian island volcanoes.
See Examiner.com for the full article.