After an impact event, the falling debris forms an ejecta blanket surrounding the crater. Approximately half the volume of ejecta falls within 1 crater radius of the rim, or 2 radii from the center of the crater. The ejecta blanket becomes thinner with distance and increasingly discontinuous. Over 90% of the debris falls within approximately 5 radii of the center of the crater. Ejecta which falls within that area is considered proximal ejecta. Beyond 5 radii, the discontinuous debris is considered distal ejecta.
- David Darling. "ejecta blanket". The Encyclopedia of Astrobiology, Astronomy, and Spacecraft. Retrieved 2007-08-07.
- French, Bevan M. (1998). "Ch 5: Shock-Metamorphosed Rocks (Impactites) in Impact Structures". Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures. Houston: Lunar and Planetary Institute. pp. 74–78.