In Yemen, the outcropping Cretaceous System consists of continental and marine clastics and carbonates which are distributed in three main lithofacies: continental (in northern provinces), transitional (in western parts of southern provinces), and marine (in eastern parts of southern provinces). These are included within the Tawilah Formation and Ahwar/Mahra Groups. The occurrence of the Tawilah Formation (Cretaceous-Paleocene) is restricted to the northern provinces. Its lower parts consist of continental (fluvial) sandstones (continental lithofacies) of Cretaceous age which constitute the Zone without diagnostic fossils. Its upper parts consist of alternations of nonmarine and fossiliferous marine sandstones of Paleocene age which constitute the Pulsiphonina prima Zone.