Living Reference Work Entry

Encyclopedia of Planetary Landforms

pp 1-6

Date: Latest Version

Chaotic Terrain (Mars)

  • Gro Birkefeldt Møller PedersenAffiliated withNordic Volcanological center, University of Iceland Email author 


Distinctive area of broken terrain that primarily consists of polygonal, flat-topped blocks of various sizes, of which many preserve remnants of the surrounding upland surface.


Chaos; Chaos region


Chaotic terrains are irregular to circular fractured areas (Figs. 1 and 2) that consist of jumbles of blocks that vary in size and shape from knobs and irregular conical mounds to angular mesas with preserved remnants of the upland plateau, and they are often located in enclosed to semi-closed depressions surrounded by fractured highlands (Sharp 1973; Nummedal and Prior 1981; Warner et al. 2011).
Fig. 1

Pyrrhae Chaos (10°S, 331°E) is an example of enclosed irregular shape chaos terrain. The basin is filled with knobs and angular blocks, and the surrounding plateau is partly fractured. Scale bar 25 km. THEMIS Day IR Mosaic (NASA/JPL-Caltech/Arizona State University)

Fig. 2

Aromatum Chaos and Ravi Vallis, Mars (43°8′W, 1°7′S; Viking Mars Digital Image Model mosaic). Examp ...

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