Relatively recently, water blasted out from an underground aquifer on Mars, carving out deep flood channels in the surface that were later buried by lava flows, radar images complied from an orbiting NASA probe shows.
The channels are at least twice as deep as previous estimates for Marte Vallis, an expanse of plains just north of the Martian equator that is the youngest volcanic region on the planet.
Most outflow channels on Mars date back billions of years, when the planet was believed to be warmer and wetter than the cold, dry desert it is today.
Marte Vallis is the exception. Channels still visible on the surface cut through very young lava flows, indicating liquid water was present in the relatively recent past. But a key piece of the story has been hidden below ground.
Using radar sounding data collected by an instrument on NASA’s Mars Reconnaissance Orbiter, scientists have created the first three-dimensional reconstruction of Marte Vallis, which reveals buried flood channels 1,000 kilometers (621 miles) long and twice as deep as analysis of surface features had suggested.
“From looking at the surface, you can see the channels were there, but you have no idea how deep it was, which is obviously important because the depth tells you something about the amount of erosion and how much water was there,” lead researcher Gareth Morgan, with the Smithsonian Institution in Washington DC, told Discovery News.
( via news.discovery.com )