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It is still disputed whether very old archaeological and palaeontological remains found in the Belle-Roche palaeocave (eastern Belgium) pertain to the Early (similar to 1 Ma) or Middle (similar to 0.5 Ma) Pleistocene. Here, in situ-produced cosmogenic Be-10 concentrations from a depth profile in nearby sediments of the Belle-Roche terrace (Ambleve Main Terrace level) are used as an indirect solution of this chronological issue. The distribution of Be-10 concentrations in the upper 3 m of this profile displays the theoretically expected exponential decrease with depth. Assuming a single exposure episode, we obtain a best fit age of 222.5 +/- 31 ka for the time of terrace abandonment. However, below 3 m, the Be-10 concentrations show a marked progressive increase with depth. This distinctive cosmogenic signal is interpreted as the result of slow aggradation of the fluvial deposits over a lengthy interval. Modelling of the whole profile thus suggests that the onset of the terrace formation occurred at around 550 ka, with a sediment accumulation rate of similar to 20 mm ka(-1). Based on two slightly different reconstructions of the geomorphic evolution of the area and a discussion of the temporal link between the cave and Main Terrace levels, we conclude that the fossil-bearing layers in the palaeokarst pertain most probably to MIS 14-13, or possibly MIS 12-11. This age estimate for the large mammal association identified in the Belle-Roche palaeokarst and the attribution to MIS 14-13 of a similar fauna found in the lowermost fossiliferous layers of the Caune de l’Arago (Tautavel) are in mutual support. Our results therefore confirm the status of the Belle-Roche site as a reference site for the Cromerian mammal association in NW Europe.