Living Reference Work Entry

Encyclopedia of Planetary Landforms

pp 1-4

Date: Latest Version

Crater Floor with Irregular Depressions

  • Jarmo KorteniemiAffiliated withEarth and Space Physics, Department of Physics, University of Oulu Email author 


Steep-walled depressions on the floors of craters.


Irregular depression crater


Mars: depressions on the floor units of impact craters (Fig. 1). Depression walls often have straight segments and exhibit layering. The parent craters tend to be shallower than the surrounding (i.e., nondepressed) craters (Korteniemi et al. 2005, 2006).
Fig. 1

Irregular depressions in a 100-km-diameter crater at 31.7°S 41.1°E, Mars. Scale bar 25 km. THEMIS day IR mosaic (NASA/JPL-Caltech/Arizona State University)


The depressions are generally 50–300 m deep and cover less than half (usually at most 20 %) of the crater floor area. Layered walls of the depressions indicate that the original crater floor was at least partly covered (by sediments?) before the depression formed. Depression shapes and sizes vary greatly; however, in many cases, one or several depression wall segments are either radial or parallel to the crater rim.


A type of crater floor modification ...

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