Golfolina, Montalbano, Florence, Prato, Pistoia, Serravalle, Arezzo, Girone, Casentino, Pratomagno, San Miniato al Tedesco, and Valdinievole

On folio 9A-9r of the Codex Leicester Leonardo takes up once again the question of the presence of marine fossils in locations far from the sea, in order to demonstrate that it was not the Great Flood which carried them to great altitudes. He observed that nichi could never be found in valleys that had not been filled with sea water in past eons, mentioning as one example the freshwater lake formed by “the large valley of the Arno” on the plain between Florence, Prato and Pistoia through which the Arno flowed from Golfolina to Serravalle. A second freshwater lake had once filled the upper valley of the Valdarno towards Arezzo, extending for 40 miles from the foot of Prato Magno – a mountain from which various rivers descended, but where he could find no traces of marine fossils – to Girone (between Florence and Pontassieve), where it then joined the lake of Perugia. Shells could instead be found where rivers approached the sea, such as those flowing from the Appenines to the Adriatic Sea or by the Arno further downstream from the Golfolina, where around San Miniato al Tedesco (but not in the Val di Nievole) there were “banks filled with nichi and ostriche (shells and oysters)”.