Holocene geomorphological and pedosedimentary archives of eastern Sahelian paleoenvironments (Kassala, Sudan)

Abstract

Studies upon past climates, natural landscapes, and environments of archaeologically pivotal regions of northern Africa have been of paramount interest in the past decades. For some of those regions, the human-environmental nexus, intended as the biunivocal mutual agency between people and nature, has been a long-standing research question; yet, for other areas, the environmental record is a still unexplored archive. Here we present case studies discussing archaeo-environmental sites from the easternmost stretches of the Sahelian belt, in the Kassala region of Sudan. Therein, in a landscape that is currently characterized by granitoid rocky outcrops dotting a vast gravelly pediplain colonized by xerophytes and thin ephemeral grass, pedosedimentary features that encase the climatic history of the region are found. By means of field survey, physico-chemical laboratory analyses, micromorphological analyses, and radiometric dating, we investigated the uppermost portion of the Quaternary record to contextualize the Late-Holocene archaeological record. The main identified features include buried isohumic soil horizons in lower flat grounds, which are legacy of water-reliant prairie environments formed in the wetter Early to Middle Holocene, and later accretional dusty aeolian deposits intermingled with colluvial gravels close to the outcrops’ eroded foothills, testimony of a climatic deterioration towards aridity and erosion driven by hyper seasonality. Results are of great importance as a contribution to a more holistic understanding of past human economies of the region, as well as being a newly added tile to the reconstruction of surface processes dynamics over Africa and their response to global climate changes.