New findings using data from NASA's Mars Reconnaissance Orbiter (MRO) show that gullies on modern Mars are most likely not being formed by flowing liquid water. This new evidence will allow researchers to further narrow theories as to the mechanisms behind the formation of gullies on Mars, and help reveal more details about Mars' recent geologic processes.
Scientists have used the term "gully" for features on Mars that share three characteristics in their shape: an alcove at the top, a channel, and an apron of deposited material at the bottom. Gullies are distinct from another type of feature on Martian slopes, streaks called "recurring slope lineae" or RSL, which are distinguished by seasonal darkening and fading, rather than characteristics of how the ground is shaped. Water in the form of hydrated salt has been identified at RSL sites. The new study focuses on gullies and their formation process by adding composition information to previously acquired imaging.
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