valleys' relations with other geological features, scientists have concluded the channels formed 2.0 to 3.8 billion years ago. Scientists have thought of different ideas for the cause of chaotic terrain. One explanation for the source of the water that quickly left the ground and created chaos is that water rich sediment was deposited in giant canyons on the floor of an ocean. Later, when the ocean disappeared, the sediments froze. If hot magma came near to the region, the ice would have melted and formed large underground river systems. When these neared the surface, huge amounts would break out of the ground and carve the valleys we see today. There is much evidence for an ocean on Mars. Places have been photographed that could be where the ground collapsed when water left an subterranean rivers to flow out of chaotic regions. One of the first theories for the source of the water was based on old Viking Orbiter pictures. It was thought that these outflows came from a global cryosphere-confined aquifer that collected water from south polar meltwater. The cryosphere would have formed during the Hesperian period in the planet's history. into the planet’s upper crust. One chaotic terrain, Galaxias Chaos may be caused by sublimation of an ice-rich deposit. In popular culture In the graphic novel Watchmen, Dr. Manhattan ponders upon the alternative viewpoints of existence, and says that Mars did not choose life, but rather "chaotic terrain". In the science fiction novel Armada (novel), Chaos Terrain is a business that makes videogames secretly designed to teach civilians how to fight Europan aliens. See also References External links Planetary geology