The rift setting of eastern Africa preserves exceptional records of mammalian (including hominin) fossils and archeology. The Afar region is host to multiple deposits with sediments ranging in age from>9 Ma to the present (Chorowicz, 2005; Katoh et al., 2016) and plays a major role in our understanding of human origins. The Gona project area contains fossiliferous deposits that span ca. 6.3 to <0.15 Ma (Quade et al., 2008); the duration of this record means that it can make a distinct contribution to understanding the environmental context for human evolution within the Afar and in eastern Africa (Figures 17.1 and 17.2). The primary units at Gona include the late Miocene Adu-Asa Formation, which contains fossils of Ardipithecus kaddaba; the early Pliocene Sagantole Formation with fossils of Ardipithecus ramidus; the mid- to late-Pliocene Hadar Formation; and the Busidima Formation (ca. 2.7 Ma to <0.15 Ma), which contains a record of the earliest Oldowan stone tools, fossils of Homo erectus, and Acheulean artifacts (Figure 17.2).