Living Reference Work Entry

Encyclopedia of Planetary Landforms

pp 1-11

Date: Latest Version

Impact Basin

  • Ross PotterAffiliated withCenter for Lunar Science and Exploration, USRA – Lunar and Planetary Institute Email author 
  • , Henrik HargitaiAffiliated withPlanetary Science Research Group, Eötvös Loránd University, Institute of Geography and Earth Sciences
  • , Teemu ÖhmanAffiliated withArctic Planetary Science Institute


The term “impact basin” usually refers to multiring basins, but it may also refer to two-ring craters with or without a central peak, or to very large degraded craters with an undefined number of rings.

The term “basin” as a morphologic category was introduced by Hartman and Kuiper (1962) to designate large lunar circular depressions (maria) with multiple ring structures and radial fault systems as opposed to craters, which lack concentric and radial structures (Hartmann and Wood 1971). Melosh (1989) defined multiring basins as large circular impact structures that “possess at least two concentric asymmetric scarps, one of which may be the original crater rim” (internal rings are generally symmetric). Morphological criteria of multiringed impact basins defined by Pike and Spudis (1987) include, outward from the interior depression: (1) isolated massifs and massif chains in circular patterns; (2) arcuate ridges aligned with massifs; and (3) scarps aligned with massifs or ridges ...

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