Clementine imaged the Moon globally in eleven different wavelengths. We used these data to construct a full resolution (250 m/pixel) multispectral image of the Orientale basin. Using this image in conjunction with other data sets, such as Earth-based spectra, we mapped the compositional units of the basin to obtain insights into its formation and evolution. The basin ejecta units are largely uniform in composition with the inner, Montes Rook Formation being slightly more mafic than the outer, Hevelius Formation. The Inner and Outer Rook mountains display many outcrops of pure anorthosite. These and other findings are consistent with a three layer model for the lunar crust consisting of a mixed zone (megaregolith) tens of kilometres thick overlying a layer of anorthosite above a basaltic layer.¿ 1997 American Geophysical Union