The left column represents generalized stratigraphy, with radiocarbon dates (uncalibrated years before present) shown as red dots on the y axis, and deposits indicated by their archaeological nomenclature. P, S/Si, Pleistocene; T, A, Holocene; Ao, Holocene ochre ashy layer; Ag, Holocene grey ashy layer (after ref. 76). Columns 1–6 display the chronological extents of technological traditions: 1, microlithic quartz industry; 2, macrolithic flake and blade industry on basalt; 3, bifaces of the axe–hoe type; 4, pecked grounded adze and arrow heads; 5, pottery; and 6, iron objects. Column 7 indicates the two burial phases. Column 8 shows climatic reconstructions based on carbon stable isotopes and pollen from organic matter extracted from sediment cores at Lake Barombi Mbo in western Cameroon (more arid conditions to the left and more humid conditions to the right60,76), along with archaeological eras. IA, Iron Age; LSA, Later Stone Age; SMA, Stone to Metal Age. RMCA Collection; drawings by Y. Paquay, composition © RMCA, Tervuren; modified by E. Cornelissen77.