Abstract The Ili basin (Figures 1 and 2) is one of the smaller Cenozoic successor basins associated with the Tien Shan ranges of southeastern Kazakhstan and western China (Allen et al., 1991; Graham et al., 1993). Nonmarine Cenozoic strata deposited in the IIi basin are best exposed at and around Aktau Mountain in the southern foothills of the Dzhungarian Alatau of southeastern Kazakhstan (Figures 1 and 2). The Cenozoic section exposed at Aktau Mountain is about 2.5 kmthick and mostly of Neogene age (e.g., Lavrov and Rayushkina, 1983); however, the lower third of this section has yielded fossil mammals of late Eocene, late Oligocene, and early Miocene age (e.g., Russell and Zhai, 1987; Abdrakhmanova et al., 1989; Tleuberdinaet al., 1993). The Aktau Mountain section preserves sedimentary rocks deposited in an array of lacustrine and fluvial environments. Here, we present a preliminary overview of these strata, including their lithostratigraphy, paleontology, and depositional systems.