Canadian and U.S. researchers say they have evidence to back up a controversial theory that suggests that one-third of the planet's surface was once covered in water.
The study, to be published Thursday in the magazine Nature, found that “ragged, kilometre-high, undulating” features on the surface of Mars are in fact shorelines of massive ancient oceans.
While the features were identified in the early 1990s, scientists were skeptical because the patterns did not match shorelines on Earth.
University of Toronto geophysicist Jerry Mitrovica said Mars experienced a 50-degree shift of its axis that dramatically warped its topography and helps explains the discrepancy.
Study author Taylor Perron of Harvard University points to the location of the Martian volcano Tharsis – the largest in the solar system – as proof.
He said the volcano is so massive that it will always reorient itself to sit on the planet's equator, and that the chances of this happening randomly are less than 1-in-10,000.
