Noctis Labyrinthus

At the western end of Valles Marineris lies a fracture region call Noctis Labyrinthus. This feature's origin is not certain, but scientists think it began to develop when volcanic activity started in the Tharsis region. The upwelling of subsurface magma lifted, stretched, and then fractured the martian crust. This activity created the large Tharsis volcanoes located nearby, and Valles Marineris to the east. In the area of Noctis Labyrinthus cracks and faults opened, ice and water in the subsurface likely escaped, and the ground collapsed. The result today is a tangle of tablelands cut by canyons, troughs, and pits.