Tsunamis waves tall enough to swallow the Statue of Liberty washed away the shorelines of Mars’s ancient ocean, according to a study published Thursday.

In the wake of their destructive force, a Martian mystery was born.

Planetary scientists had hypothesized for decades that a primordial ocean might have once covered much of the red planet’s northern hemisphere. Last year they presented molecular traces of atmospheric water that backed the claim. But still missing from their theory were visible traces of the ocean’s coastline.

They essentially had evidence of an ancient ocean, but could not find its shore.

“We’re showing that the shorelines were there, but they were overrun and buried by the tsunami waves,” said J. Alexis Rodriguez, a Mars geologist at the Planetary Science Institute in Tucson, Ariz., and an author of the paper.

Using images from spacecrafts orbiting Mars, Dr. Rodriguez and his colleagues identified what they say are geological remnants like boulders and ice debris left from the tsunamis. They published their results in the journal Scientific Reports.