Based on what you know now, do you think the channel on Mars was formed by flowing water or flowing lava? *

most likely lava

Explanation:"We found terraced walls on the insides of these channels, channels that go out and just disappear, channels that cut back into the main one, and vertical walls 9 meters (~29 feet) high," Bleacher says. "So, right here, in something that we know was formed only by flowing lava, we found most of the features that were considered to be diagnostic of water-carved channels on Mars."

The new results make "a strong case that fluid lava can produce channels that look very much like water-generated features," says Zimbelman. "So, we should not jump to a water-related conclusion when we see such channels on other planets, particularly in volcanic terrain such as that around the Tharsis Montes volcanoes."

Further evidence that such features could be created by lava flows came from the examination of a detailed image of channels from the Mare Imbrium, a dark patch on the moon that is actually a large crater filled with ancient lava rock. In this image, too, the researchers found channels with terraced walls and branching secondary channels.

The conclusion that lava probably made the channel on Mars "not only has implications for the geological evolution of the Ascraeus Mons but also the whole Tharsis Bulge [volcanic region]," says Andy de Wet, a co-author at Franklin & Marshall College, Lancaster, Penn. "It may also have some implications for the supposed widespread involvement of water in the geological evolution of Mars."