1. Latitudinal Trend of Roughness and Circumpolar Mantles on Mars M. A. Kreslavsky J. W. Head III Brown University

2. Statistical characterization of kilometer-scale topography with MGS MOLA data M. A. Kreslavsky, J. W. Head (2000) JGR-Planets, v. 105, no. E11, p. 26,695 - 26,711 + some new results MOLA - measurements of the surface elevation: ~ 600 000 000 shots 0.3 km shot-to-shot distance along track up to 1.5 km gaps between tracks up to 0.3 m vertical precision up to 3 m vertical accuracy

3. Baselines used: 0.6 km 2.4 km 9.6 km d characterizes profile curvature at given point at given baseline. We calculated d for each shot and binned into map cells Map grid: 8x8 cells per degree. Typically ~40-80 shots per map cell

4. Curvature-frequency distribution: a statistical characteristic of topographic pattern For each map cell we calculated interquartile width of the distribution. It characterizes roughness at given baseline for given map cell. All map cells form a roughness map for each baseline We combined 3 maps for 3 baselines into one color map Baselines used: 0.6 km 2.4 km 9.6 km

5. Blue0.6 km baseline Green2.4 km baseline Red9.6 km baseline Brighter = Rougher Roughness map

6. Olympus Mons AureoleOlympus Mons Aureole: very rough Amazonis and Elysium Planitia: very smooth Dune fields: rough at small scale, flat in large scale Polar caps: smooth at small scale; steep larger-scale slopes than highlandsVolcanic plains are smoother than highlands Northern lowlands are rather smooth and have characteristic 3-km-scale roughness Roughness map

7. S hemisphere: highlands at low latitudes are rougher (30N - 30S) highlands at high latitude are smoother (>60S) at 0.6 km baseline N hemisphere: Similar trend partly masked with the dichotomy boundary and other intrinsic roughness contrasts. Interpretation that survived tests with high-resolution MGS MOC images: Manifestation of unique type of surface mantle deposits with specific meter-scale texture Latitudinal trend of roughness

8. MGS MOC image M03/04333 The deposits with specific fine texture (center) are superposed over underlying topography at 47N in Utopia Planitia 500 m

9. MGS MOC image M23/01695 Dark dunes travel over the deposits with specific texture at ~75N and leave no traces. The deposits are strong, probably cemented 500 m

10. The deposits with specific texture show complex stratigraphy. The uppermost layer 4 m thick is removed in some places. Circular features are impact craters of cratered cones, degraded and mantled. 500 m MGS MOC image M02/01316

11. High-latitude surface mantle deposits: Very likely cemented by water ice May be desiccated at lower latitudes (30-60) (Mustard et al., 2001) Currently undergoing slow degradation at margins (?) (Mustard et al., 2001) > 1-3 m thick ( <= roughness signature) ~3 m thick at margins ( <= MOC images, Mustard et al., 2001)

12. High-latitude surface mantle deposits: Diverse morphology Complex stratigraphy History of successive deposition and removal Persisted through at least Late Amazonian Undergo changes during obliquity cycles A range of processes operating ( <= MOC high-resolution images)