Soldani Ambrogio (or Baldo Maria)

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(b. Pratovecchio, Arezzo, Italy, 15 June 1736; d. Florence, Italy, 14 July 1808)


The son of Dr. Soldano Soldani and Benedetta Nesterini, Soldani dropped the name Baldo Maria and assumed that of Ambrogio in 1752, when he entered the Camaldolese Congregation. Although an exemplary monk, he was active in the cultural life of Siena, where he spent most of his life. With the economist Sallustio Bandini, he reorganized the celebrated Accademia dei Fisiocritici, and in 1781 he was appointed professor of mathematics at the University of Siena.

Soldani was not only a mathematician, however, but also an ardent naturalist. In his studies of Pliocene marine formations of Tuscany and of preexistent ones bordering the Pliocene sea he proved to be an accomplished geologist, describing with great accuracy the lithological. stratigraphic. and paleontological characteristics of the deposits. Although his emphasis on the study of microscopic fossils (he described and drew hundreds of them, from mollusks to foraminifers) entitles him to be considered a paleontologist, Soldani never approached paleontological research as an end in itself. His desire to study the microfauna of the Mediterranean, which was almost unknown in his time, derived from his conviction that knowledge of present zoological conditions would have decisive consequences for the correct interpretation of the deposits left by the ancient seas.

In deposits of the Pliocene Tuscan sea, especially in those found near Siena and Volterra, Soldani identified three layers: an abyssal, formed by material of marine origin: a littoral, formed by material of terrestrial origin: and an intermediate, formed by both marine and terrestrial material. In addition he showed the presence of lacustrine microfauna in the sediments of the early Pleistocene Tuscan lakes that have since disappeared (such as Valdarno Superiore). Soldani’s studies distinguished him as a leader in establishing the interrelation of zoology and paleontology; and he deserves considerable credit for his efforts to derive, from present conditions, material for the study of the geological past. Unfortunately he made no effort to classify systematically the many species that he described and distinguished. The harsh criticism, especially in this respect, of his most important work, the Testaceographia, so embittered him that he burned all copies of the work in his possession.

Soldani also studied the celebrated meteorites that fell in the region around Siena in 1794. Reasoning on the basis of eyewitness reports and on lithological study of the meteorites, he excluded any possibility of their terrestrial origin, proposing instead that they originated from a condensation of atmospheric vapor. This fallacious hypothesis, as well as that of their extraterrestrial origin, appeared absurd at the time to scientists; and Soldani was derided in a lively polemic.

An impartial evaluation of Soldani’s entire work was not possible until after his death. Charles Lyell assigned him a prominent place among eighteenth-century naturalists, and not merely that of a founder of micropaleontology.


I. Original Works. Three basic works by Soldani are Saggio orittografico, ovvero osservazioni sopra le terre nautiliche ed ammonitiche della Toscana (Siena, 1780): Testaceographia ac Zoophitographia parva et microscopica, 4 vols. (Siena, 1789–1798). very rare, partly because Soldani destroyed copies; and Sopra una pioggetta di sassi accaduta nella sera de’ 16 giugno del MDCCXCIV in Lucignan d’Asso nel Sanese (Siena, 1794).

II. Secondary Literature. See E. Manasse, “Commemorazione di Ambrogio Soldani,” in Atti dell’ Accademia dei fisiocritici di Siena, 4th ser., 20 (1908),. 365–376: O. Silvestri, “Ambrogio Soldani e le sue opere,” in Atti della Società italiana di scienze naturali, 15 (1872), 273–289 and F, Rodolico, “Ambrogio Soldani e Ottaviano Targioni Tozzetti: carteggio sulla ‘pioggetta di sassi’ del 1794,” in Physis, 12 (1970), 197–210.

Francesco Rodotico