Fossa
Large troughs (long narrow depressions) are called fossae in the geographical language used for Mars. This term is derived from Latin; therefore fossa is singular and fossae is plural. Troughs form when the crust is stretched until it breaks. The stretching can be due to the large weight of a nearby volcano. Fossae/pit craters are common near volcanoes in the Tharsis and Elysium system of volcanoes.
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Labeatis Fossae, as seen by THEMIS.
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Close-up view of Labeatis Fossae, as seen by THEMIS.
Read more about this topic: Lunae Palus Quadrangle