DefinitionThe crater rim is the edge of the crater typically elevated above the original ground surface. The maximum elevation of the rim is the rim crest.SynonymsBasin rim (for basins), Rampart (Elger 1895, obsolete), Ring mountain (obsolete)Related TermRimless crater, rim crestDescriptionThe crater rim consists of autochthonous, structurally elevated bedrock (Poelchau et al. 2009) overlaid by a thick layer of overturned allochthonous (displaced) ejecta (impact) (Fig. 1).Fig. 1Cross section of crater rim (Watters 2010). (hr) Rim height, (hu) stratigraphic uplift (Melosh 1989)Just outside of the crater rim is the zone of the outward-sloping continuous ejecta blanket, smothering the underlying terrain. Ejecta deposits decrease in thickness outward from the crater rim. The inner rim walls are much steeper than the external slopes.Complex craters are characterized by terraces resulted from inward collapse (slumps) inside the rim, enlarging the crater and broadening the rim-to-rim diameter ...