Steno, the fossils, the rocks, and the calendar of the Earth
This paper deals with the influence that geological research in Italy during the seventeenth and eighteenth centuries had on the reconstruction of Earth's history. The identification of the true nature (i.e., organic) of fossils by Fabio Colonna in the early seventeenth century and, later in the century, the Stenonian sedimentary geology in agreement with the Genesis and the volcanological studies of Giovanni Alfonso Borelli gave the learned men of the Modern Age important tools in order to establish a numerical dating of Earth's age.
In the seventeenth and eighteenth centuries, two Italian people, Jacopo Grandi and Francesco Bianchini, and the French Charles De Brosses, tried to build a calendar of the past of the world on the basis of natural and historical records. Even if they used the data in a profoundly different way, they reached (in fact, they wanted to reach) the same results: the confirmation of the same calendar of Earth's history elaborated by the most famous Bible chronologists at the middle of the seventeenth century (Lightfoot, 1642; Ussher, 1654). De Brosses rejected the Italian dating, following the steps of his friend Buffon. He enlarged the geological calendar but did not understand, just like the two Italians, that at that time any absolute dating of the age of our planet was impossible.