Dorsa Argentea Formation
Southern circumpolar assemblage of smooth plains and distinct surface features that underlies polar layered terrain (Dickson and Head 2006) on Mars.
DAF represents the volatile-rich lag deposit of a decayed expansive circumpolar dust-rich ice sheet that formed in the Hesperian and underwent subsequent volcanically induced bottom-up and also top-down melting, sublimation, and retreat (Head et al. 2003). In this model sinuous ridges are eskers, sinuous valleys are meltwater transport channels, pits and cavi are localities of volatile loss (e.g., kettle holes in outwash plain), and pedestal craters formed by vertical degradation and volatile loss (Head and Pratt 2001). This is the currently favored formation model (Dickson and Head 2006; Ghatan and Head 2004).
Hesperian (Tanaka and Scott 1987).
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