This is Scientific Americans 60 Second Science.

I'm Lee Billings.

Got a minute?

For as long as we've been sending spacecraft to Mars,

we've been finding signs of water.

The red planet sinuous river valleys, flood-carved canyons, and buried glaciers all hint that it was wet billions of years ago.

Some researchers think that the curiously flat and sparsely cratered northern lowlands are the remnants of a once-grade ocean.

But that ocean's proposed coast varies in height by thousands of meters, which has made the idea controversial.

Now, a team of researchers has found evidence for ancient tsunamis on Mars,

evidence that supports the idea of a vanished Martian ocean

and explains its vertically variable shoreline.

We were trying to find shorelines on Mars,

like those we typically see on Earth,

which is consistently distributed on a constant elevation,

and that is not what we have found on Mars because in the case of Mars

the shorelines were buried beneath tsunami deposits.

Alexis Rodriguez of the Planetary Science Institute in Tucson he led a team that used satellite images to identify thick deposits of boulders and silt

apparently left by two separate tsunamis, a few million years apart,

almost three and a5 billion years ago.

The discovery of the tsunami deposits represents definite evidence for the existence of the

early Martian ocean.

The tsunamis were enormous.

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