The doctoral thesis of Otto Renz on the Scaglia in the Central Apennines, published in 1936, led the foundation for the enduring fame of the region of Gubbio, Italy, as a special place to study the geohistory of the Cretaceous and the Paleogene.

Abstract Eight depositional sequences are recognized within marine Paleogene strata of the Tremp Basin (Southern Pyrenean Foreland Basin). Geometry and distribution of the depositional systems are mainly controlled by tectonics and relative sea-level changes. Carbonate systems dominate during sea-level highstands, siliciclastic systems during sea-level lowstands. Biostratigraphic boundaries inherently tend to correspond to sequence stratigraphic surfaces (condensed sections, intervals of non-deposition). Biostratigraphic correlations provide only a rather loose framework and should not be overstretched. In marine Paleogene units of the Southern Pyrenees, their resolution is generally not sufficient to identify individual global eustatic 3rd order cycles without ambiguities.