The biostratigraphy of Cretaceous/Tertiary boundary sections from eight localities is summarized and compared in order to define a continuous or complete section. The El Kef, Tunisia, section is apparently the thickest C/T boundary section as yet discribed and contains all the biostratigraphical criteria required to define a complete section; that is, the uppermost Cretaceous Micula prinsii Zone, the “boundary clay” within the lowermost Tertiary Globigerina fringa Zine, followed by the Globigerina eugubina and pseudobulloides Zones. Using these zonations, a correlation of the stable-isotope stratigraphy from the various sections was made. The latest Cretaceous oceans and the earliest Tertiary oceans contained...