Two Letters of Signor Giovanni Arduino, Concerning His Natural Observations: First Full English Translation. Part 2

A translation is provided of Arduino's second letter to Vallisnieri Jr (written 1759, published 1760) concerning his interpretation of the strata in Valdagno, near Recoaro in the southern part of the Alps of northeast Italy. Based on lithostratigraphic considerations, he envisaged a fourfold chronologic division of the strata of the region, that overlay the base or ‘primogenial’. rocks'. This gave rise to the notions of Primary, Secondary, Tertiary and Quaternary strata. (But only the term ‘fourth Order’, not Quaternary, was used by Arduino.) His work came to be recognised as a major contribution to chronostratigraphy, but perhaps he did not himself recognise its future significance or ‘potential’. He stated that the ‘Primary’ rocks contained a few fossils and that the Secondary and Tertiary strata were highly fossiliferous. His was not, then, a biostratigraphic classification in a modern sense But he used the different fossil organisms to differentiate his ‘Orders’. Also he appreciated that the younger strata were produced from the erosion products of the older ones.