Hebrus Valles

Located west of the Elysium Volcanic complex, Hebrus Valles is a channel system that flowed to the north. The process that formed the channel system is unknown. Some of the channel features, as in this image, have the appearance of being formed by liquid flow on the surface of the plains. In other portions of the valles, there are pits and collapse features which appear to have formed by material falling into subsurface voids. This is a common feature in regions of volcanic activity where lava tubes run below the surface. Both water and lava probably contributed to the formation of Hebrus Valles. Hebrus Valles is located in southern Utopia Planitia and is 325km (202 miles) long.