Apollo 16 4 and 5 rake samples were examined petrographically and by electron microprobe and INAA. Results were combined with published information (major and trace element compositions, petrologic information, and age determinations) for nonrake samples from stations 4 and 5 and some other Apollo 16 sample localities. Lithologic abundances support idea (Korotev, 1981) that the variation of soil compositions at Apollo 16 is a result of mixing between a component represented by station 5 soil and components much like either the dimict breccias (station 4 soils) or feldspathic fragmental breccias (stations 1, 2, and 11) in compositions. Dimict breccias, because of their restricted occurence, are apparently not a constituent of either the Cayley or Descartes formations: they were contributed to the surface materials by South Ray crater and were probably excavated from beneath both formations by this event. Pyroxene, olivine, and coexisting plagioclase compositions from within the anorthosite portions of dimict breccias bridge the gap between the Mg-rich and ferroan anorthosite fields. Analyses from associated cumulate and granulitic clasts indicate that they are the source of the intemediate material: dimict breccia anorthosites are thus polymict rocks, not pristine ferroan anorthosite. Compositions of Apollo 16 impact melt rocks suggest a number of compositional clusters. Discriminant and cluster analyses of compositional data confirm the existence and strength of these clusters, as do age determinations and Ir/Au ratios within each group. Each of three clusters represents an impact event in the Apollo 16 region. Petrologic information and age determination indicate that dimicit breccias formed approximately 3.92 b.y. ago. The Nectaris event occured between 3.84 and 3.92 b.y. ago, and the Cayley plains were deposited as a result of the Imbrium event sometime later than 3.84 b.y.