When this paper was first published, the incorrect version of Figure 11 was included. The correct figure is printed below: [Figure presented] Fig. 11. Maps showing the occurrence of Early Pleistocene records of Macoma balthica and Viviparus glacialis. Open dots: M. balthica present, V. glacialis absent; Black dots: V. glacialis present, M. balthica absent; Grey dots: V. glacialis and M. balthica present. Zuurland-2 (site 68) is the only Dutch site where both these species co-occur; the other sites are either pre-Late Tiglian or else are exclusively non-marine. All British sites with V. glacialis also yield M. balthica. Supplementary Table 2 provides details of the sites.