How depositional environments impact the microwear preservation of quartz artifacts: insights from the Oldowan of the Shungura Formation (Ethiopia)

The function of Oldowan tools is a key aspect of early hominin subsistence in eastern Africa. The rarity of the sites, the preservation of the assemblages and raw materials are limiting factors in the functional study of Early Pleistocene assemblages. The archaeological occurrences from Member F of the Shungura Formation (Ethiopia) have a precise chronostratigraphic framework (2.324 ± 0.020 Ma to 2.271 ± 0.041 Ma), a detailed reconstruction of depositional environments, and artifacts produced mainly from small quartz pebbles that are highly resistant to chemical and mechanical alterations. The studied archaeological material comprises artifacts from 12 occurrences and three environmental contexts (floodplain, point bar, and channel lag). As a baseline for distinguishing taphonomic damage from use-wear, and for assessing the preservation of use-wear in the archaeological record, we characterized macroscopic and microscopic surface alterations resulting from fluvial transport and aeolian abrasion experiments. Despite the good preservation of the lithic assemblages at a macroscopic scale, variations were observed at a microscopic level corresponding to the depositional environment. Understanding the link between taphonomic alterations on quartz and the type of deposits leads to better recognition and interpretation of potential use-wear on these ancient artifacts.