Reference work entry
An impact crater displaying muted topography in a volatile-rich target material.
Terrain softened crater (antonym: unsoftened crater)
Structure of impact craters depends on the target material (e.g., Strom et al. 1992; Barlow and Perez 2003; Stewart and Valiant 2006) and can exhibit distinct structures if the target is rich in volatiles (e.g., Senft and Stewart 2008). An impact into a target substrate that is volatile-rich or contains buried volatiles can result in a crater with a “softened” form compared to an impact into a substrate with no volatiles. Using imagery, Jankowski and Squyres ( 1992) assessed craters in the mid-latitudes of Mars for crater depth, convexity or concavity of crater wall, rounding of the crater rim, and rim height. They found that softened simple and complex craters had rounded rims and more convex crater-wall slopes; and otherwise sharp features were rounded (Figs. 1 and 2). Softened craters are shallower than unsoftened...
- Banks ME, Byrne S, Galla K, McEwen AS, Bray VJ, Dundas CM, Fishbaugh KE, Herkenhoff KE, Murray BC (2010) Crater population and resurfacing of the Martian north polar layered deposits. J Geophys Res 115, E08006. doi:10.1029/2009JE003523Google Scholar
- Barlow, NG, Perez CB (2003) Martian impact crater ejecta morphologies as indicators of the distribution of subsurface volatiles. J Geophys Res 108. doi: 10.1029/2002JE002036Google Scholar
- Dombard AJ, McKinnon WB (2006) Elastoviscoplastic relaxation of impact crater topography with application to Ganymede and Callisto. J Geophys Res 111:E01001. doi:10.1029/2005JE002445Google Scholar
- Koutnik M, Byrne S, Murray B (2002) South polar layered deposits of Mars: the cratering record. J Geophys Res 107:10-1–10-10. doi:10.1029/2001JE001805Google Scholar
- Masursky H (1964) A preliminary report on the role of isostatic rebound in the geologic development of the lunar crater Ptolemaeus. Astrogeologic studies, annual progress report A. U.S. Geological Survey, Washington, DC, pp 102–134Google Scholar
- Milliken R, Mustard J, Goldsby D (2003) Viscous flow features on the surface of Mars: observations from high-resolution Mars Orbiter Camera (MOC) images. J Geophys Res 108. doi:10.1029/2002JE002005Google Scholar
- Parsons RA, Nimmo F (2009) North–south asymmetry in Martian crater slopes. J Geophys Res 114. doi:10.1029/2007JE003006Google Scholar
- Perron JT, Dietrich WE, Howard AD, McKean JA, Pettinga JR (2003) Ice-driven creep on Martian debris slopes. Geophys Res Lett 30. doi:10.1029/2003/GL017603Google Scholar
- Schaller EL, Murray B, Pathare AV, Rasmussen J, Byrne S (2005) Modification of secondary craters on the Martian South Polar Layered Deposits. J Geophys Res 110. doi:10.1029/2004JE002334Google Scholar
- Strom RG, Croft SK, Barlow NG (1992) The Martian impact cratering record. In Mars: Kieffer HH, Jakosky BM, Snyder CW, Matthews MS (eds). The University of Arizona Press, Tucson, AZ, pp 383–423Google Scholar
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