Fig 1.
Western Africa archeological map.
(A) Location of Fatandi V with surveyed or excavated archaeological occupations and sites mentioned in the text. (B) Location of Fatandi V and surveyed sites in Falémé valley (map design by Laboratory Archaeology and Population in Africa (APA) of the Department of Genetics and Evolution (University of Geneva) based on views from USGS Earth Resources Observatory and Science Center and CIA World Factbook).
Fig 2.
Geomorphological context of the archaeological site of Fatandi.
(A) General situation; (B) Main stratigraphical and geomorphological units; (C) Detailed cross-section showing sedimentary units (U) and pedological subunits. Caption: 1. Excavated area; 2. Archeological and geomorphological sections; 3. Archaeological layer; 4. Location of OSL, phytolith and micromorphologic samples; 5. Illuvial horizon; 6. Carbonated illuvial horizon (figure designed by L. Lespez based on data from fieldwork).
Fig 3.
Photos of Fatandi V site and excavations.
(A) Concentration 1, collecting artefacts in 2013. (B) North-south trenches, view from the south, 2013 field campaign. (C) North square during 2013 excavation. (D) Detail of the lithic concentration in North square during 2013 excavation. (E) North square in the foreground and North trench extension in the background at the end of 2014 excavation. All photos by B. Chevrier.
Fig 4.
Location of the surface concentrations and excavated sectors during 2012 to 2014 field missions.
Fig 5.
Artefact concentrations profiles in the North trench and its extension.
Fig 6.
Drawing of the lithic concentration in the North square (drawing by B. Chevrier).
Fig 7.
Comparison of the natural luminescence signals in LM-OSL mode for samples F11, F12, and F13 with a reference quartz [26] (signal generated by irradiation ß of 20 Gy).
The signal is measured over a period of 2,000 s (here only the first 500 seconds are shown), while the strength of the electroluminescence diodes is risen linearly from 0 to 60 mW/cm2. It is worth noting that the signal is dominated by the fast component and is thus adapted to OSL dating by the SAR protocol.
Fig 8.
SAR protocol applied to the samples from Fatandi V.
(a) For the first measurement cycle, no dose was applied. (b) The preheats tested range from 200 to 280°C, maintained for 10 s. (c) The stimulation lasts 100 s for the multi-grains, 1 s for the single-grains; the signal and the background noise selected in order to calculate Lx and Tx are calculated respectively for the first 0.3 and last 0.5 seconds in multi-grain mode, and the first 0.17 and last 0.15 seconds in single-grain mode. (d) The test dose was set at 5 Gy for all samples. (e) The preheat (cutheat) after application of the test dose is 160°C, not maintained. (f) D is chosen in order so that the equivalent estimated dose for the first batch of aliquots is roughly equivalent to 3D.
Table 1.
Count of artefacts longer than 2 cm, in surface for Concentration 1, in stratigraphy for excavated areas.
All artefacts smaller than 2 cm were collected by area, but were not systematically quantified for the current study.
Table 2.
Data relevant for the calculation of the dose rate.
Table 3.
Results obtained for the dose recovery tests.
Fig 9.
Abanico plot [55] for sample F3, in multi-grain mode.
Table 4.
Data relevant to the calculation of the equivalent dose for each sample according to different statistical models, without stratigraphic constraints.
Fig 10.
Synthesis of OSL dates obtained with the Bayesian baSAR-Normal model, with (in orange) and without (in blue) stratigraphic constraints.
The results of Archeophases for each stratigraphic unit are also indicated (in green). Light and dark colors indicate respectively 68% and 95% confidence level. The relative stratigraphic positions are represented. The chrono-stratigraphic positions of F2, F4, F10 on the one hand and F1, F3, F9, F11 on the other, are not strictly known, hence their representation on the same level. The lines between F1/F2, F3/F4 and F9/F10 remind the relative stratigraphic correlations that are known between the two groups and that have been used in the Bayesian model.
Table 5.
Ages obtained for the single-grain data with the Bayesian baSAR-Normal model, with and without stratigraphic constraints (SC).
Fig 11.
Microphotographs (XPL) of F9 thin section showing calcitic infillings (11a) quasi-coating in a channel structure and a calcitic nodule (11b).
Fig 12.
Phytoliths assemblages of eight samples from U1 and U2 in Fatandi V.
The stratigraphic relationships between the U1 samples have not been indicated here to better highlight the links between F1 and F11 on the one hand and between F3, F4, F9 and F10 on the other hand.
Fig 13.
Quantitative data per 1/16 m2 and spatial interpretation of the distribution of Concentration 1 artefacts.
(A) Distribution of the artefacts longer than 2 cm. (B) Spatial interpretation of the concentration and diffusion of the artefacts longer than 2 cm. (C) Distribution of the artefacts smaller than 2 cm. (D) Displacement of 20 localized artefacts between 2012 and 2013 field missions. (E) Distribution of the weight/number ratio of the artefacts smaller than 2 cm. (F) Spatial interpretation of the concentration and diffusion of the artefacts smaller than 2 cm.
Fig 14.
Interpretative model of the erosion of the archaeological level (B) compared to geomorphological and stratigraphical data (A).
Fig 15.
1 to 3: Method 1 bladelet cores; note the refitting of a splitted slab on n°3. 4: Bladelet core with frontal exploitation of a ridge. 5: Narrow bladelet refitted on the n°4 bladelet core. 6: Bladelet core with convergent production organized following two asymmetric surfaces. 7: Debordant short blade refitted on the n°6 bladelet core (drawings and photographs B. Chevrier).
Table 6.
Inventory of the lithic assemblage from North square of Fatandi V.
Fig 16.
1 to 8, and 9a to 9b: Bladelets produced from method 1 bladelet cores. 9c: Refitting of 9a and 9b bladelets. 10a to 10c: Bladelets produced from method 2 bladelet core. 10d: Refitting of 10a to 10c bladelets (drawings B. Chevrier).
Fig 17.
NS = natural surface (drawings B. Chevrier).
Fig 18.
1: Bladelet refitted on core n°2. 2: Bladelet and flake core. 3: Technological analysis of the chaîne opératoire showing two stages of production (bladelet debitage, then flake debitage). 4: Photograph of the core (drawings and photographs B. Chevrier).
Fig 19.
Toolkit from excavations and surface.
1: Segment from North square. 2: Segment from Next-4 section. 3 to 6: Segments collected on surface, close to excavated sectors, made on jaspoidal grauwacke. 7: Segment collected on surface, close to excavated sectors, longer than the other segments and highly weathered. 8: Retouched natural blank. 9: Retouched elongated flake (drawings and photographs B. Chevrier).
Table 7.
Dimensions of the two segments found in stratigraphy and the five segments collected on surface.
Fig 20.
1: Small hematite pebble, fractured and striated. 2: Fractured sandstone pebble with hammered surfaces (photographs B. Chevrier).