Abstract— Small terrestrial hypervelocity impact craters have a bowl‐shaped form and are partially filled by an interior breccia lens, roughly parabolic in cross‐section, of allochthonous material. This interior breccia volume is geometrically modelled as the volume of material slumped off the interior wall of the transient cavity during late stage crater modification. This model is tested by comparing the estimated volume of the breccia lens based on observational data with the calculated volume of slump material based on known dimensional parameters. The model fits well for Meteor Crater and Brent and is highly sensitive to changes in input parameters ( e.g. , a 10% increase in the input diameter for Meteor Crater produces an almost 200% increase in the model breccia lens volume). Further testing of the model with less constrained data from West Hawk Lake and Lonar leads to reasonable fits, given the sensitivity of the model to input parameters. Fits to other craters: Aouelloul, Tenoumer and Wolf Creek, where previous depth data are constrained only by gravity data, are unsatisfactory. However, revised depths can be obtained that fit both the gravity data and the model. While these tests do not provide unqualified support for the model, they do suggest that it may represent a good first order approximation. More and better quality dimensional data are required for more rigorous testing.
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