Ed Anders suggested that samples from terrestrial craters should be analysed. The idea was to see if impactors of terrestrial craters can be identified by their high siderophile element contents, similar to that assumed for the Moon. In Chicago samples were analysed with the same procedures as lunar samples. The first attempt failed. Breccias from the Ries crater had no obvious meteoritic contamination. Morgan et al. (1979) suggested a differentiated meteorite with no or very low concentrations of metallic elements.

Richard Grieve from the Geological Survey of Canada provided samples of large Canadian Craters, which we analysed in Chicago. In...

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