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A. T. Basilevsky (Vernadsky Institute, Moscow), G. Neukum (Freie Universitaet Berlin), B. A. Ivanov (Institute of Dynamics of Geospheres, Moscow), S. C. Werner, S. van Gasselt (Freie Universitaet Berlin), J. W. Head (Brown University), R. Jaumann, H. Hoffmann, E. Hauber (DLR-Institut fuer Planetenforschung, Berlin), HRSC Co-Investigator Team
The High Resolution Stereo Camera (HRSC) images taken at orbit 143 show a consistent and measurable high-resolution view of western Olympus Mons. Numerous lava flows, some as young as 2-3 m.y. [1], have been observed at the studied part of the volcano. At the edge of the edifice slope close to the scarp, several mesas and one ridge composed of layered deposits are observed suggesting sedimentation of dust (maybe ash) and ice. The presence of ice is deduced from the observation of deep rimless depressions within the mesas and from the specific interaction of the mesa material with lava flows. On several parts of the volcano slope, chaos-like depressions, channels and chains of rimless craters suggest the melting of ground ice, surface collapse, and water run-off, perhaps due to lava invasion. At the foot of the scarp, and further to the lowlands, lobate flows, morphologically similar to terrestrial rock glacier deposits, are observed. Some of them are only 4 m.y. old [1], implying recent episodes of glaciation probably controlled by changes of the planet's orbital parameters [2]. Morphologic evidence of older glacial deposits at high altitude (+7.5 km) above the scarp was also found. References: [1] Neukum et al., Nature, 2004 (submitted); [2] Lascar et al., Icarus, 170, 343-344, 2004. Acknowledgement: This work was supported by the German Space Agency (DLR) and the German Science Foundation (DFG).
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.