Reasons for a name

Born in Liege in 1809, the French-speaking André-Hubert Dumont was the son of a mining surveyor. An enfant-prodige familiar with the stratigraphy of his home country, the self-taught geologist was not inclined to use fossils to define stratigraphic subdivisions, remaining skeptical in the introduction of the Silurian and the Devonian as advocated around 1839 by British geologists. When he introduced the Ypresian stage in 1850, for a part of the Eocene sequence outcropping at Ieper in the West Fiandres (Ypres is the French name of Ieper), he based his criteria on facies.

  Winner at the age of 21 of the gold medal of the Académie royale des sciences de Belgique, with his Mémoire sur la constitution géologique de la province de Liège, Dumont became the protegée of the influent Jean-Baptiste d’Omalius d’Halloy, his countryman. The young geologist was the right person to complete the work that d’Omalius had outlined, the geological map of Belgium. The Mémoire contained descriptions and a general scheme of the Primary series, Secondary formations being more limited in extension. In 1839 Dumont was ready to present a general survey of the Tertiary, in his way to complete the map, relying on mineralogic characters more than on fossils to differentiate finer stratigraphic subdivisions. At this step of the project he had introduced the stage Landenian (“Système landénien”, after the town of Landen), to incorporate mudstone and sandstone outcropping in the East Fiandres. Ten more years would pass by before the geological map was ready for publication. Meanwhile, he had redifined Eocene terrains by including a Ypresian “system” between the Landenian and the Bruxellian.

Learn More Dumont A.-H. (1839). Rapports sur la carte géologique pendant l’année 1839. Bulletin de l’Académie Royale de Belgique 6, 464-485. Steurbaut É. (2006). Ypresian. Geologica Belgica 9, 73-93.