ALLUVIAL SEDIMENTOLOGY OF A HOLOCENE ARCHAEOLOGICAL TRANSITION AT SAI ISLAND, SUDAN

The sedimentologic context of ceramic-bearing site 8-B-76, on the west side of alluvial Sai Island in northern Sudan, reveals localized depositional shifts due to Nile River migration between early and mid-Holocene occupations, at the transition from a foraging (Khartoum Variant ‘Mesolithic’) to a herding (Abkan ‘Neolithic’) occupation. Channel deposits give way to stable river-margin environments and overbank deposition during the early Holocene Khartoum Variant (KV). These deposits were then incised and replaced by channel bar deposits also containing KV ceramics, which may represent a second KV occupation. A later period of channel migration away from the western margin of Sai Island led to silty overbank deposition with no archaeological materials despite a more stable landscape, suggesting an occupational hiatus on this part of the island. The lack of evidence for a human presence in this otherwise well-utilized area may be attributable to higher flood volumes and therefore less habitable floodplain environments during the mid-Holocene African Humid Period. The uppermost unit in the area preserves mid-Holocene Abkan ceramics within accretionary aeolian sediments, indicating more arid conditions and an absence of late-Holocene deposition or reworking along the western margin of Sai Island.