Major features of the Moon's Procellarum KREEP Terrane include subdued relief and extensive resurfacing with mare basalt, consistent with high concentrations of Th and other heat-producing elements at depth. We relate the chemistry of sampled materials to the geomorphology, Th surface concentrations determined by the Lunar Prospector (2° pixels), and FeO and TiO₂ concentrations derived from Clementine ultraviolet-visible spectral data. On the basis of geologic maps, each pixel was classified as mare, terra, or mixed. Near the periphery of the terrane, terra pixel compositions are relatively feldspathic; in the interior they mainly represent Imbrium basin rim or ejecta deposits and are mainly incompatible trace element rich norites and presumably represent materials from a thick section (tens of kilometers) of the pre-Imbrium crust of the terrane excavated by the Imbrium event. (Although Imbrium ejecta are the principal source of surface terra materials, the Imbrium event did not create the Th-rich Procellarum KREEP Terrane.) Broad, continuous expanses of mare pixels are observed, with little interruption from protruding terra or terra-penetrating craters. The mare-basalt-dominated regoliths of these areas have a wide range of TiO₂ concentrations (<1 – 15%) and higher Th concentrations (2 to 6+ ppm) than most sampled mare basalts. Traverse profiles show high Th over broad regions of highest FeO (>18%), leading to the conclusion that the high Th concentrations are in the mare basalts and are not present in the regoliths as terra-derived materials. Volcanic glasses and impact glasses of mare basalt composition collected from the Procellarum KREEP Terrane support this conclusion.