Tractus Catena

This VIS image shows part of Tractus Catena, just one of many north/south trending tectonic graben located south and east of Alba Mons. The features running vertically and horizontally in the image are both part of Tractus Catena. The horizontal section is younger than the vertical section, but it is not known when the horizontal part formed in relation to the vertical. While other graben in the area are identified as fossae (defined as a long, narrow depression), the circular depressions within these graben lead to the descriptor name catena (defined as a chain of craters). In this case the craters are a result of roof collapse into an underlying open space such as a lava tube.