Information sign for the GSSP of the Seelandian stage (lower Upper Paleocene) at Zumaia section, Spanish Basque Country. The sign is mounted near the “golden spike” on the top plane of the uppermost limestone bed of the Aitzgorri Limestone Formation which is identical to the basal plane of the overlying red marls of the lowest part of the Itzurun Formation (right-hand outside the picture).[1]