Water gushes created "staircases" on Mars: study

By Will Dunham

WASHINGTON (Reuters) - Sudden, tremendous gushes of water from underground most likely carved out unusual fan-shaped geological formations with steps like a staircase long ago on the surface of Mars, scientists said on Wednesday.

The Martian surface boasts perhaps 200 large basins that have formations resembling fans. About 10 of them are terraced, with what looks like steps into the basin. Since they were first seen three years ago, scientists have debated how these formations, some of them 9 miles wide, were created.

Dutch and U.S. researchers simulated on Earth on a vastly smaller scale the conditions that might have led to these formations on Mars that resemble dry river deltas with steps.

At a facility at Utrecht University in the Netherlands, they dug a crater in sand in a room-sized tub, then started water flowing into the crater. As the water flowed in through a channel, it eroded the sediment, then fanned out and deposited sediment as deltas, building steps down into the basin, very much like the Martian formations.

Erin Kraal, a researcher at Virginia Tech University who led the study published in the journal Nature, said these Martian formations probably formed quickly -- in a period of decades not hundreds, thousands or millions of years.

And they involved a lot of water.

"What you could imagine is something like the Mississippi River flowing for 10 years and then turning off, or the Rhine River flowing for 100 years and then turning off," Kraal said in a telephone interview.

"It's hard to image being able to get that much water to start so suddenly and stop so suddenly," Kraal added.