Giovanni Arduino (1714-1795) was a leading figure in the Italian scientific community in the second half of the 18th century. Among the contributions made by the European scientists to the origin of stratigraphy, Ardui­no's system of subdividing rocks into four basic units called "ordini" attained a unique level of precision. His lithostratigraphical theory, presented in 1760 and refined in 1775, has been regarded by several geologists and historians as starting point of the modern chronological subdivisions of the Earth's geological history. Arduino's 'classification' was based on extremely accurate fieldwork. In fact, his essay Due Lettere to Antonio Vallisnieri junior (published in 1760) contained the scientific results of a geological travel through the Agno Valley, in the Venetian Prealps of northern Italy: the data collected during this fieldtrip, undertaken in October 1758, may be found in his handwritten notes and in two sketches, kept in the Public Library of Verona (Italy). These valuable papers show clearly the origin of Arduino's lithostratigraphical theory. In particular, the impressive drawing entitled "Representation of the strata of different kinds of rocks, obser­ved on right riverside and on left riverside of Agno, from Mon­tecchio Maggiore to the highest tops of the Alpi, above Recoaro, during my journey on 19-20-21-22 and 23 October 1758, of these strata are made the hills and the moun­tains" has become a classic image for the early history of geology. It is a real and graphically modern geological cross-section of the Agno Valley in only one plane, giving sixteen lithostratigraphical units, which are carefully described by Arduino in the handwritten captions below the sketch.

The aim of this paper is to reappraise Arduino's cross-section in the light of an 'experimental' approach, which will try to reconstruct the fieldwork carried out by Arduino in the Agno Valley, in order to understand the genesis of his famous visual representation in connection with his lithostratigraphical theory.