Site 1 (locus 1) lies between 78.11 m and 65.70 m altitude, corresponding to the top and bottom of the basaltic lava flow. He delivered in his US 2 layer (sedimentary unit 2) a total of 23 oldowayen stone tools. The US 2 layer was covered by a basaltic flow initially dated to 1.57 Ma, which gave it an age of about 1.6 Ma. The dating of this layer has since been revised to about 1.2 Ma, making it still the oldest known prehistoric deposit in France to date.

This dating is based on the crossing of paleomagnetism and the age of the many paleofaunal fossils found at the site, including lagomorphs (hares and rabbits), already known in Spain in geological layers of equivalent age.