New research using data from a variety of Mars orbiters suggests that large tsunamis previously smashed against the shores of the red planet, shaping the geography.
The group zeroed in on a region on Mars where the highlands known as Arabia Terra bump up against the lowlands of Chryse Planitia — a place where the waters of an ancient ocean might have lapped at the shoreline. Using imagery from several Mars-orbiting spacecraft, Rodriguez’s group identified two particular geological formations that they say formed during two different tsunamis. The first, older formation looks as if an enormous wave had rushed up onto the edge of the highlands, dropping boulders as big as 10 metres across. The water then drained back down into the ocean, leaving channels cut through the freshly deposited debris.
Then, millions of years passed. Temperatures dropped and glaciers crept across the landscape, scouring deep valleys. Finally, a second impact-generated tsunami came rushing again towards the shore. “But this time it is different,” Rodriguez says. Because the climate was so much colder, the tsunami moved over the landscape like an icy slurry. It froze before it had a chance to wash back into the ocean, leaving dense lobes of frozen debris on the ground.
They propose the waves were caused by large meteorite impacts. They also admit that there are large uncertainties in their theory and conclusions.