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Arduino’s lithostratigraphical sequence of the Agno Valley

Italy

View of the Agno Valley (www.itinerarioenergia.it/).

View of the Agno Valley (www.itinerarioenergia.it/).

Geological Period

Pre-Permian to Quaternary

Main geological interest

History of geosciences
Stratigraphy and sedimentology

Location

Vicentinian Alps, Veneto Region, Italy.
45°41’32”N, 011°16’51”E

View of the Agno Valley (www.itinerarioenergia.it/).

The site where Giovanni Arduino established in 1758-1760 his lithostratigraphical theory in four units, the basis of modern stratigraphic chronology.

Giovanni Arduino’s study and representation of the lithostratigraphical sequence of the Agno Valley (1758), led to the publication in 1760 (Ell, 2011-2012) of a new theory of sub-division of rocks into four units according to the chronological order of their formation. This classification included mountains – defined as ‘Primary’ (with a basement of schists and mineral-bearing crystalline rocks; now Paleozoics) ‘Secondary’ (stratified limestones with fossils; now Mesozoics) and ‘Tertiary’ (clays, fossiliferous sandstones and some volcanic material; now Cenozoics) – as well as the most recent terrain of the plains, defined as the ‘Fourth unit’ (Vaccari, 2006). Arduino’s system established the scientific notions of Primary, Secondary and Tertiary strata, and contributed to the later definition of Quaternary (Gibbard, 2019).

Strata of "biancone" (white limestones of Cretaceous age, Mesozoic), Mt. Castrazzano, Agno Valley; identified by Arduino as secondary “fine-grained limestones”. (Photo courtesy of Ezio Vaccari).

Strata of “biancone” (white limestones of Cretaceous age, Mesozoic), Mt. Castrazzano, Agno Valley; identified by Arduino as secondary “fine-grained limestones”. (Photo courtesy of Ezio Vaccari).

  • Geological description

The Agno Valley is located in the mountain area of the Venetian Prealps called the “Vicentinian Alps”, north-west of Vicenza in north-eastern Italy. Oriented from northwest to southeast following the course of the Agno River, the valley shows a stratigraphic sequence from Paleozoic (Pre-Permian) to Cenozoic (Quaternary) exposed along its length of c. 20 km. In the upper Agno Valley, within the area of Recoaro and at the base of Mt. Spitz and Mt. Civillina, the Pre-Permian metamorphic crystalline basement (quartz-phyllites) of the Southern Alps crops out and is unconformably overlain by Permo-Triassic sedimentary cover of limestones and sandstones, the latter succession also occurring at Scandolara and Castrazzano mountains (Barbieri et al., 1980; De Zanche and Mietto, 1981). In the mid- and lower Agno Valley, from Novale to Montecchio, the outcropping rock units comprising the surrounding mountains decrease in age from Jurassic, Cretaceous to Eocene and Oligocene. Occurrences of volcanics from two magmatic cycles traverse or are intercalated within the stratigraphic sequence: in the Middle Triassic (acid and basic rocks) and in the Paleogene (basaltic rocks). In the lowest part of the Agno Valley, Holocene gravelly-sandy alluvial deposits lay at the junction with the Po Valley plain.

  • Scientific research and tradition

The lithostratigraphy of the Agno Valley was reconstructed for the first time in 1758 by G. Arduino, and later by P. Maraschini (1824). During the second half of the 19th century, palaeontological studies were by K. Schauroth, A. De Zigno, A. Massalongo, E. M. Mojsisovics, E. W. Benecke, A. Bittner and A. Tornquist. In 1939 the first geological cartography was published by R. Fabiani.

Arduino's cross-section of the Agno Valley (top) compared to a modern profile of Civillina, Scandolara and Castrazzano mountains (below).Thick black lines indicate Geological Era divisions. (Figures modified by Ezio Vaccari).

Arduino’s cross-section of the Agno Valley (top) compared to a modern profile of Civillina, Scandolara and Castrazzano mountains (below).Thick black lines indicate Geological Era divisions. (Figures modified by Ezio Vaccari).

  • Reference

Arduino, G. (1758) ‘Representation of the strata of different species of rocks, observed on right and left of river Agno, from Montecchio Maggiore as far as the highest summits of the Alps above Recoaro, in my journey of 19.20.21.22 and 23. October 1758 – of which strata hills, mounts and mountains are composed’. manuscript in Biblioteca Civica (Public Library) of Verona (Italy), Fondo G.Arduino, b.760, IV.c.11 (45 x 30 cm / 18 x 12 in).

Barbieri, G. et al. (1980) ‘Note illustrative della carta geologica dell’area di Recoaro alla scala 1:20.000’, Memorie di scienze geologiche, pp. 23-52 (with 1 geological map and 1 table of cross sections).

De Zanche, V. and Mietto, P. (1981) ‘Review of the Triassic sequence of Recoaro (Italy) and related problems’, Rendiconti della Società Geologica Italiana, 4, pp. 25–28.

Ell, T. (2011) ‘Two Letters of Signor Giovanni Arduino, Concerning His Natural Observations: First Full English Translation. Part 1’, Earth Sciences History. Edited by D. Oldroyd, 30(2), pp. 267–286. Available at: https://doi.org/10.17704/eshi.31.2.c2q4076006wn7751.

Ell, T. (2012) ‘Two Letters of Signor Giovanni Arduino, Concerning His Natural Observations: First Full English Translation. Part 2’, Earth Sciences History. Edited by D. Oldroyd, 31(2), pp. 168–192. Available at: https://doi.org/10.17704/eshi.31.2.c2q4076006wn7751.

Gibbard, P.L. (2019) ‘Giovanni Arduino – the man who invented the Quaternary’, Quaternary International, 500, pp. 11–19. Available at: https://doi.org/10.1016/j.quaint.2019.04.021.

Vaccari, E. (2006) ‘The “classification” of mountains in eighteenth century Italy and the lithostratigraphic theory of Giovanni Arduino (1714–1795)’, in G.B. Vai, W. Glen, and E. Caldwell (eds) The Origins of Geology in Italy. Geological Society of America, p. 0. Available at: https://doi.org/10.1130/2006.2411(10).

  • Author(s)

Ezio Vaccari.
International Commission on the History of Geological Sciences (INHIGEO) / Università degli Studi dell’Insubria. Italy.

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