Buffon (1707–1788) als geologischer Pionier

During the eighteenth century Paris was the center of Enlightenment. By the scientific revolution at the end of the Middle Ages man lost his central position for the intellectual thoughts. Nature became increasingly the focus of research. In addition to the descriptive inventory physical–technological thinking based on mathematics also progressed. In this transition period was Georges-Louis Leclerc, comte de Buffon a typical representative (1707–1788) (Fig. 1 ). He was both a man of letters, a philosopher and also familiar with the mathematics, biology and geology of his time. Besides, he became also an entrepreneur. Though geology occupies a much less important place than biology in his publications, he became a pioneer in this field. He arranged the former purely descriptive Histoire naturelle in seven Periods, with a directional evolution of the earth: cooling from a molten mass to a future earth covered completely with ice. Amidst this evolution the sea had covered our globe completely. Then the sea level sunk continuously. The propagation of these two directional trends was pioneer work. Nevertheless he allowed also some transgressions. To better understand the sea bottom of former times he stressed on the importance of observations of present processes in the sea and on land. He is therefore also a pioneer of actualism, and thus must be discussed together with Füchsel and Werner, as well as with Hutton and Lyell, the former as classical representatives of a primarily historical geology, the two others as pioneers of physical geology asking for processes and their causes. Finally he tried to solve the question of the exact age of our earth experimentally. In his iron works (Fig. 2 ) he observed the cooling of cast iron globes with different diameters (Fig. 3 ). From the results he published an age of some 75,000 years, a pioneer approach and statement too. Privately he discussed even millions of years. Of course many of his ideas sharply contradicted a verbal interpretation of biblical texts. Therefore, he had repeated conflicts with the Theological Faculty of the Sorbonne. Fig. 1 Georges-Louis Leclerc, Graf von Buffon (1707–1788) Montbard: Denkmal und Büste im Museum Foto E.S., 2001 Fig. 2 Die Große Schmiede Buffons um 1780 am Ufer der Brenne. Rekonstruktion: Rignault and Demir 1988, aus Benoit and Pichon (1992) Fig. 3 Abkühlung von Eisenkugeln verschiedenen Durchmessers von Weißglut bis ( a ) zur Berührbarkeit und ( b ) zur Raumtemperatur. Ordina