Hawke and Head, 1977
Hawke and Head, 1977 - Impact Melt on Lunar Crater Rims(glossary entry)
Part of the energy of an impact event totally melts target rocks and some of that impact melt is thrown out of the growing crater and falls back onto the crater floor and surrounding rim. We can only detect melt that is emplaced at the end of the crater forming process - any earlier melt is covered by later falling ejecta. Impact melt is not volcanic rock - it is a unique instantaneous melting. Impact melt has been found in terrestrial impact craters such as Manicougin.
The classic study of melt on 56 craters of diameters 300 to 4 km was published by B. Ray Hawke and Jim Head in 1977. Their information on melt distribution is included in this wiki. More melt undoubtedly exists, especially on farside craters where high resolution imaging is still lacking in 2007 - 30 years later!
Impact melt is typically difficult to see from Earth because of its small extent, but deposits are visible just south of Theophilus, and part of the floor of Copernicus is covered in melts.
Newer work by the same team is reported in Hawke, B. Ray & Head, J. W. (1992) "The distribution and modes of occurrence of impact melt at lunar craters" in International Conference on Large Meteorite Impacts and Planetary Evolution, p 37-38.
Hawke, B. R. & Head, J. W. (1977) "Impact melt on lunar crater rims" in Impact and explosion cratering: Planetary and terrestrial implications; Proceedings of the Symposium on Planetary Cratering Mechanics, Flagstaff, Ariz., September 13-17, 1976. New York, Pergamon Press, Inc., p. 815-841.
- tychocrater Aug 8, 2007