By Ron Cowen
A catastrophic outpouring of water–four times the volume of Lake Tahoe–may have gushed from fissures near the equator on Mars as recently as 10 million years ago. Images of the fissures and their surroundings, taken by the Mars Global Surveyor spacecraft, reveal landforms like those carved by catastrophic flooding on Earth, researchers report.
The set of fissures stretches more than 1,000 kilometers along a lava-rich region north of the equator called the Cerberus plains and appears to be the source of recent, small eruptions of lava. If the fissures provide both heat and water, the region could be a prime place to look for evidence of life on the Red Planet, the researchers note.
Devon M. Burr and Alfred S. McEwen of the University of Arizona in Tucson and Susan E.H. Sakimoto of NASA’s Goddard Space Flight Center in Greenbelt, Md., describe their findings in the Jan. 15 Geophysical Research Letters.
The most compelling evidence that water has flowed in the region is the presence of flat-topped mesas, each a few hundred to a few thousand meters long, that lie in the middle of channels just downslope of the fissures.
Shaped like teardrops, these mesas are similar to structures found in parts of the northwestern United States. The terrestrial mesas are believed to have been created by a mammoth release of water from melting glaciers.
The Martian mesas lie behind craters and consist of finely spaced horizontal layers, which also suggests they were deposited by a flow of water. The fissures cut through young, only lightly cratered lava plains. That indicates that if the fissures are the source of water, they were active just 10 million years ago, the team says.
