The map of Tyrol by von Buch
Among the documents that belonged to Achille De Zigno there is a geological map of South Tyrol drawn by Leopold Von Buch (1774 – 1853). The map is dated 1822 and it is very important in the debate between neptunists and plutonists about the origin of the rocks: magmatic or sedimentary.
The map is the result of Von Buch’s excursions there for 5 months. He went ‘on foot, with an umbrella and an overcoat, walking 14 hours a day – he was already in his fifties – with a complete library in his pockets, debating on mineralogy with imaginary adversaries, and getting excited about fantasy quarrels’, according to the description by Humboldt.
What were those quarrels about?
Von Buch’s teacher was a promoter of the ‘neptunist theory’ according to which all rocks were formed from the crystallisation of primordial ocean waters; the most ancient and deepest are the granites. Plutonism, on the contrary, espoused that most rocks have a volcanic origin, and come from primordial magma. In 1819, two years before the compilation of the map, Marzari Pencati reported that in Predazzo he had found granitic rocks on top of sedimentary rocks. That discovery subverted the neptunist theory, which said that granites are primordial rocks which are found under sedimentary rocks (secondary).
Predazzo is at the centre of Von Buch’s map.
The manuscript of the map has a dedication to Adelaide Emo Capodilista, and we can imagine that it had been a present for her marriage with Achille De Zigno in 1848. Von Buch and De Zigno went together on some excursions during Von Buch’s stay during the Congress of Italian scientists that was held in Venice in 1846.
The geological map had been published in vol. 23 (1823) of the Annales de chimie et de physique, as an attachment to the essay Lettre de M. Léopold de Buch à M. A. de Humboldt renfermant le Tableau géologique de la partie méridionale du Tyrol, p. 276-304.
The International Geological Congress of Bologna (1881)
Among De Zigno’s correspondence, his membership card for the 2nd International Geological Congress of Bologna, 1881, was found. The card was signed by the President of the Congress, Capellini. The Congress was fundamental above all for stratigraphic geology and saw the birth of the Italian Geological Society. On this occasion, De Zigno made an important palaeontological donation to the Museum of Bologna
There are other documents related to the Congress held in Bologna in 1881, among them an invitation to a soirée given by Capellini on the evening of September 29th (but habit de matin is enough) and an invitation to a City Hall concert on September 30th.
Among the documents that the Geosciences Library received with the donation of 2021, are the diplomas that De Zigno obtained as a member or President of important scientific Institutions, both Italian like Società geologica, Accademia dei Lincei, Società italiana delle Scienze detta dei XL, and foreign, like Societé Géologique de France, Societas Caesarea Curiosus Mosquensis, Academia Germanicae Naturae Curiosorum, and the Geological Society of London.
