At the time of Charlemagne, Lombardy was divided into five provinces: Neustria, Austrasia, Aemilia, Littoraria marls and Tuscia.
They consist for the most part of marls with Orbitolina concava, and are referred to the Cenomanian.
The Tertiary system includes conglomerates, sandstones, limestones and marls, which appear to be of Eocene, Oligocene and Miocene age.
The Triassic rocks are arranged in two groups, a lower, composed of conglomerates and sandstones, and an upper one consisting of red and mottled shales and marls with thin sandstones and nodular limestones.
Extremely valuable and varied marls, kaolins and clays, fuller's earth, asphaltum and mineral waters show special promise in the state's industry.