Between 23 million years and 5 million years before our era, during the Tertiary era, the Aquitaine Basin was occupied by a sea called the Sea of Faluns.
Traces of this sea are visible in Salles, mainly in the form of shells and the remains of fish or cetaceans, in particular teeth, compacted in land
(shell stones), some of which were mined in the Salles quarries.
Nowadays, these traces of the Sea of Faluns appear in the old fence walls and some houses, as well as in the cliff on the right bank of the Eyre bridge.