The liquid surge came from fissures near the martian equator, the same cracks that have issued forth great gobs of lava, the research team said.

"This is a completely different water release mechanism than previously studied on Mars," said Devon Burr, a doctoral student in geosciences at the University of Arizona in Tucson.

Poring over images from the Mars Global Surveyor, Burr and University of Arizona professor Alfred McEwen found strong evidence that catastrophic floods beset the lava-covered Cerberus Plains.

Comparable deluges left behind similar landforms on Earth, according to the Arizona pair, who with NASA scientist Susan Sakimoto reported their findings in a recent edition of the journal Geophysical Research Letters.

In the 1970s, satellite pictures from the Viking spacecraft convinced many scientists that colossal water floods carved great gullies on Mars.

But those deluges were thought to have taken place more than 2 billion years in the past. Burr and McEwen's study of a valley system just north of the equator shattered the timeline for major water activity on Mars.

"Athabasca Valles is an almost new component in the martian hydrological cycle," Burr said. "The water here gushed from volcano-tectonic fissures. While the fissures themselves may be older, the latest eruption of the water was probably only about 10 million years ago."

Such geothermal sites on Mars could still be active, providing the cold, dry planet with periodic doses of heat and water, McEwen said.

http://www.cnn.com/2002/TECH/space/02/27/mars.floods/index.html