Named for Richard A. F. Grieve, geologist with the Geological Survey of Canada and chief of their geophysical surveys. Grieve is a leading investigator of impact craters on the earth and moon. He maintains the global census of recognized terrestrial impact structures and has spearheaded the effort to obtain reliable ages for these structures. He also has been a leader in classifying the impacting bodies on the basis of siderophile element abundance patterns in impact melt rocks. (M 4451) _ _.