The Red Planet had a fiery and watery past. New research reveals that beginning about 3.5 billion years ago, five episodes of violent volcanic activity spewed lava and hot water onto the Martian surface, sculpting the landscape into the dimpled world we see today.
Unlike on Earth, researchers say, the fashioning of the Martian surface has proceeded in spurts and stops. The rocky slabs that form Earth's outer surface steadily inch along to mold the mountains and valleys that shape our planet.
More: http://www.space.com/scienceastronomy/080317-volcanic-mars.html