Many distinct layers are visible in the south wall of the crater. Layering is a widespread feature on Mars and has been documented extensively since theMars Global Surveyor mission returned high-resolution images of the planet’s surface.[2][3]
Rock layers on Mars can form through several geological processes, including volcanic activity, wind deposition, or water-related sedimentation.[4][5][6]
A comprehensive overview of Martian sedimentary layering is provided in Sedimentary Geology of Mars.[7] Grotzinger and Milliken have discussed how both wind and water likely contributed to the formation of these layers.[8]
Immediately south of McMurdo crater lies a field of short, dark streaks and fans. These features are formed by the seasonal sublimation of carbon dioxide in the spring, when rising temperatures cause pressurized gas to escape through the surface. The escaping CO2 gas carries dark material, which is then deposited downwind, forming streaks and fan shapes. Because of their appearance, these features are sometimes referred to as “spiders.”[9][10][11][12][13][14][15]
Short dark streaks and fans caused by outgassing of carbon dioxide and dark material. Layers in the crater wall are clearly visible. Image taken with the CTX camera (on Mars Reconnaissance Orbiter).
^Grotzinger, J. and R. Milliken (eds.). 2012. Sedimentary Geology of Mars. SEPM.
^Grotzinger, J.P. and R.E. Milliken (2012). The sedimentary rock record of Mars: Distribution, origins, and global stratigraphy, SEPM Special Publication, 102, 1–48.
