Theories of the Earth and 'Plutonism' in the Introduzione alla geologia by the Italian geologist Scipione Breislak (1811).

Scipione Breislak may be considered as one of the most renowned Italian ‘Plutonists’ at the end of the eighteenth and beginning of the nineteenth centuries. In the 1790s, he was a professor of Physics at the Military Academy of Nunziatella in Naples, where he also devoted himself to the study of Vesuvius and the Phlegraean Fields. Thus, he acquainted himself with volcanic phenomena. Breislak’s works about the volcanic fields of Campania (Southern Italy) disclosed how Torbern Olof Bergman’s theories and Antoine-Laurent de Lavoisier’s chemistry had affected his belief in the idea that volcanic eruptions were triggered by ignition of petroleum deposits. After a voluntary exile in France, owing to the downfall of the Roman Republic, Breislak returned to Italy and settled in Milan, where he was appointed as an Inspector of Gunpowder in 1802. Due to his new administrative duties, he had the opportunity to continue studying mineralogy and geology, focusing primarily on the stratigraphy of Lombardy and of the Alps. During the ‘Milanese period’, he published the Introduzione alla geologia (Introduction to geology, 1811), which may be regarded as the first Italian handbook about the ‘new’ science of Geology. In the monograph, he also drew on Huttonian ideas in order to describe the lithostratigraphic features of crystalline rocks. Without neglecting Breislak’s volcanological hypotheses, this paper aims to analyze the influence that nineteenth-century Plutonist (Huttonian)geological theories had on the Earth’s history that he depicted in the Introduzione alla geologia. The influence of Plutonism—a term that Richard Kirwan introduced to define James Hutton’s geological system—may also be recognized in Breislak’s rejection of transition rocks. Indeed, according to him: “nature does not make passages or transitions, and each of its products has a specific and particular way to exist” (Breislak 1811, volume 1, pp. 308–309).