Mars: water means surfing

Surfing in Mars might have been a possibility. NASA's Curiosity rover mission has found evidence a stream once ran vigorously across the area on Mars where the rover is driving.

There is earlier evidence for the presence of water on Mars, but this evidence - images of rocks containing ancient streambed gravels - is the first of its kind. Imagery shows an alluvial fan of material washed down from the rim, streaked by many apparent channels, sitting uphill of the new finds.

The rounded shape of some stones in the conglomerate indicates long-distance transport from above the rim, where a channel named Peace Vallis feeds into the alluvial fan.

The abundance of channels in the fan between the rim and conglomerate suggests flows continued or repeated over a long time, not just once or for a few years.

"The shapes tell you they were transported and the sizes tell you they couldn't be transported by wind. They were transported by water flow," said Curiosity science co-investigator Rebecca Williams of the Planetary Science Institute in Tucson, Arizona.

Scientists are studying the images of stones cemented into a layer of conglomerate rock. The sizes and shapes of stones offer clues to the speed and distance of a long-ago stream's flow.