Reasons for a name

During the earlt decades of the 19th century Barton was a small village on the Hampshire coast, facing the Isle of Wight in the South East of England. The Barton cliff was known among savants for the rich and well-preserved fossil fauna that Daniel Solander, the Swedish scholar of Karl Linnaeus, had described a few decades earlier on specimens belonging to the Gustavus Brander collection. The stratigraphic meaning of the Barton strata came under the attention of Thomas Webster, the first to recognise analogies between the English and French Tertiary formations. As knowledge progressed, marine mudstone of the Barton cliff, lying on top of the Bracklesham Beds and the London Clay, were found to be in their turn overlain by freshwater formations studied by a young Charles Lyell.

The Swiss geologist Charles Mayer, or Karl Mayer-Eymar as he would later be called, was a promising young fellow who had travelled Europe and collected fossil molluscs from the many sites he visited in Europe. After studying in Paris under Elie de Beaumont and Adolphe d’Archiac (Dolfuss 1908), at the age of 32 he proposed a subdivision of the Tertiary into 12 stages, six for the lower and six for the upper Tertiary (Mayer 1858). In dividing the Tertiary in two parts, after discussing other subdivision already proposed by Charles Lyell and Heinrich Ernst Beirich, Mayer followed the lesson of Elie de Beaumont. He would then restrict the use of the Parisian stage, for instance with respect to the use advocated by d’Alcide d’Orbigny a few years earlier (1850), and introduced three new stages for the upper part of the lower Tertiary: Bartonian, Ligurian and Tongrian. The Parisian comprised the lower part of the Coarse Limestone formation, outcropping in Paris and its outskirts, corresponding in England to the Bracklesham and Bagshot beds. In the Bartonian he included the Barton marine strata, comprising both mudstones and sandstones of the Hampshire basin, and the Beauchamp sands in France (Sable de Beauchamp), comprising the thick marine succession today outcropping at Guépelle, to the North of Paris. Karl Mayer’s stages encountered approval and respect, given his fame of excellent field geologist and paleontologist, and his synoptical tables were further refined in several later editions (Sacco 1907).   The spectacular succession of the Isle of Wight, in the Hampshire Basin, remains today a reference section as a “stratotype of the unit” (Flugeman 2004, Agnini et al. 2011). Learn more Agnini C., Fornaciari E., Giusberti L., Grandesso P., Lanci L., Luciani V., Muttoni G., Pa?like H., Rio, D., Spofforth D.J.A. & Stefani C. (2011). Integrated biomagnetostratigraphy of the Alano section (NE Italy): A proposal for defining the middle-late Eocene boundary. Geological Society of America Bulletin 123, 841-872. Brander G. (1766). Fossilia Hantoniensia Collecta, et in Musaeo Britannico Deposita, a Gustavo Brander. London. Dollfus G.F. (1908). Nécrologie Ch. Mayer-Eymar. Journal de conchyliologie 56, 145–162 d’Orbigny A. (1850). Prodrome de paléontologie stratigraphique universelle des animaux mollusques et rayonnés fossiles. Paris: Masson. Volume 2, 427 p. Mayer K. (1858). Versuch einer neuen Klassifikation der Tertiär-Gebilde Europas. Verhandlungen der Schweizerischen naturforschenden Gesellschaft 42, 165-199. Sacco F. (1907). Carlo Mayer-Eymar. Cenni biografici. Bollettino della Societá Geologica Italiana 26, 585–602. On the web Barton and Highcliff Eocene Strata (Ian West’s instructive and colourful webpage). Official site for the study and valorisation of the Guépelle fossil site (in French). Fossils from the Barton Beds (Alan Morton’s “A collection of Eocene and Oligocene fossils”). Karl Mayer’s original article can be downloaded at the ETH Library website.