THEMIS Image of the Day, October 25, 2016. This VIS image shows some of the graben which form Noctis Labyrinthus. Graben are formed when pairs of faults cause the material between them to move downward, creating the linear trough. The circular features in the graben near the bottom of the image are thought to form from collapse of surface materials in free space created by lava tubes that flowed within the pre-existing graben.
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