LDAs were first observed in Viking orbiter data, and were interpreted to be members of a class of features indicative of the presence of ground ice [Carr and Schaber, 1977; Squyres, 1978, 1979]. Deuteronilus Mensae (Figure 1; 40–51°N, 14–35°E), part of the dichotomy boundary “fretted terrain” [Sharp, 1973] contains a high concentration of LDAs [Squyres, 1979; Squyres and Carr, 1986; Hauber et al., 2008] that occur at the bases of scarps of mesas, knobs, craters and valley walls [Chuang and Crown, 2009]. Relief of the adjacent scarps is generally 1–2 km, and most of the LDAs themselves have 300–800 m of relief relative to the surrounding valley floors. LDAs are typically ∼10 km wide, measured perpendicular to the trend of the adjacent scarp, with a range of widths of 5–25 km [Li et al., 2005]. Analysis of topographic profiles of LDAs showed them to be consistent with viscous deformation of an ice-rock mixture [Colaprete and Jakosky, 1998; Mangold and Allemand, 2001; Li et al., 2005] but the percentage of ice required to cause flow, and the amount remaining today are uncertain. Ice-assisted creep of talus [Squyres, 1978, 1979] implies less than ∼20–30% interstitial and secondary ice, while debris-covered glaciers could be >80% ice covered by a thin debris lag [Colaprete and Jakosky, 1998; Head et al., 2005, 2006a, 2006b], and rock-glacier-like deposits imply intermediate values (30–80%) [Mangold et al., 2002]. Head and Marchant  and Head et al. [2006a, 2006b], analyzed lobate and linear debris aprons (and related lineated valley fill) in the Deuteronilus region and interpreted them as debris-covered remnants of glaciers that formed during the Late Amazonian. Image data show many features indicative of flow and surficial modification likely related to the presence of subsurface ice in the LDAs of this region and in LDAs elsewhere on Mars [e.g., Carr and Schaber, 1977; Squyres, 1978, 1979; Mangold and Allemand, 2001; Mangold, 2003; Pierce and Crown, 2003; Chuang and Crown, 2005; Head et al., 2005, 2006a, 2006b; Chuang and Crown, 2009]. In summary, a range of approaches and analyses suggests that ice is important in the formation of the distinctive shapes, profiles, and textures of LDAs, but the exact amount of ice and its mode of emplacement have been controversial.