In situ-produced 10Be and 26Al indirect dating of Elarmekora Earlier Stone Age artefacts: first attempt in a savannah forest mosaic in the middle Ogooue valley, Gabon

Discovered in 1988 by R. Oslisly and B. Peyrot, Elarmekora is a high terrace that, today, is situated 175 m above the Ogooue River in the historical complex of Elarmekora, attached to the Lope National Park in Gabon, a World Heritage site since 2007. The site yielded a small lithic assemblage, including mainly cobble artefacts embedded within the 1 m thick alluvial material. Based on geomorphological and palaeoclimatological criteria, the preliminary dating suggested an age of 400 ka. However, Elarmekora could be a key site for Atlantic Central Africa if this lithic industry can be dated absolutely. In 2018 and 2019, two field trips were organized to collect surface samples as well as samples in vertical depth profiles with the aim of measuring their in situ-produced cosmogenic nuclide (Be-10 and Al-26) content. Results suggest a surface abandonment between 730 and 620 ka ago representing a minimum age for the cobble artefacts. Concurrently, technological reappraisal of the artefacts suggests an atypical lithic industry that should, for the moment, be considered as 'undiagnostic' Earlier Stone Age. This age bracketing may be compared with a similar age range obtained for prehistoric occupations in Angola using the same approach. This age will place Elarmekora among the oldest evidence for the presence of hominins in western Central Africa and raises the question of a 'West Side Story' to early human dispersals in Africa. This article is part of the theme issue 'Tropical forests in the deep human past'.

Automated summary

Elarmekora, a historical site near Lope National Park in Gabon, is considered a key site for Atlantic Central Africa. Preliminary dating based on lithic assemblage and geomorphological criteria suggests an age of 400,000 years. Through field trips and measurements of cosmogenic nuclides, the minimum age of the cobble artefacts is estimated to be 730-620,000 years. This finding proves the early presence of hominins in western Central Africa.