Canyon, shoreline proof of lake on Mars

WASHINGTON: A long, deep canyon and the remains of beaches are perhaps the clearest evidence yet of a standing lake on the surface of Mars - one that apparently contained water when the planet was supposed to have already dried up, scientists said on Wednesday.

Images from a camera called the High Resolution Imaging Science Experiment aboard the Mars Reconnaissance Orbiter indicate water carved a 50-km-long canyon, a team at the University of Colorado at Boulder reported.

It would have covered 200 sq km and been up to 450 meters deep, the researchers wrote in the journal Geophysical Research Letters.