«All of the outflows of water from the mountains to the sea bring with them rocks from those mountains to that sea; and due to inundations of the sea's water striking against the mountains, these stones were thrown back toward the mountain; and in the backward and forward flux of the seawater, the stones were carried along with it, and in returning their sharp edges beat against one another and, being the part less resistant to impact, were consumed, leaving the stones without sharp edges, but rounded, as can be seen on the beaches of Elba. The stones that have not moved from the time of their origin remain the largest; and conversely, those that move furthest from the aforesaid place become the smallest, being transformed successively into minute pebbles, and then into sand, and lastly into mud. Then as the sea withdraws from the aforesaid mountains, the salt left by the seawater, combined with other humours of the earth, forms an agglomeration of these pebbles and sand, in which the pebbles become transformed into stone, and the sand into tufa rock.

[…] An example of this can be seen in the Adda, where it flows from the mountains of Como, as well as in Tesino [Ticino], Adige, Oglio and Adriano dell'Alpi de' Tedeschi; and the same in the Arno, at Mount Albano, around Monte Lupo and Capraia, where the great rocks are all made up of agglomerated pebbles, of different stones and colours.

That thing will be the lightest, the further it be brought by the rivers from the place from which their waters took it; and so the heaviest will be the one carried for the least distance from the place where it split off […]» (f. 6A-31v).

«[…] And if you tell me that the "nichi" (fossil shells), being empty and dead, have been swept here by the waves, I say that the place where they were found dead is not far from where they once lived, and in these mountains are found live specimens of all the known ones, which have a double shell and live in a place where none of the dead ones are found; and a little higher up is the place where all of dead ones, with their double shells broken in half, were thrown by the waves.

Near where the rivers fell into the sea at a great depth, like the Arno, which fell from the Golfolina near Monte Lupo, they left pebbles, which can still be seen in the form of conglomerations, and stones from various lands, of different nature and colour and hardness, that have formed a single agglomeration; and a little further on, the conglomerating of the sand has formed tufa rock, at the bend of the river toward Castel Fiorentino. Further on the mud in which the "nichi" lived was deposited on the riverbed, which, rising higher by degrees, depending on whether the turbid floodwaters of the Arno flowed into that sea and gradually raised the seabed over the course of time, produces said "nichi" by degrees, as shown by the gorge of Colle Gonzoli, broken off by the river Arno, which consumes its foot: in which gorge can be clearly seen the aforesaid degrees of "nichi" in a bluish mud, and various other things of the sea are found there […]" (f. 8B-8v).»

«[…] There where the valleys received no salt water from the sea, no "nichi" were ever seen: as is clearly evident in the great valley of the Arno above Golfolina, a boulder in ancient times conjoined with Monte Albano in the form of a very high river bank; it kept the river engorged so that before it flowed into the sea, which lay at the foot of that boulder, it formed 2 great lakes, of which the first is where today we see the city of Florence flourishing, along with Prato and Pistoia; and Monte Albano followed the rest of the high bank as far as the present-day Serravalle. In the upper Valdarno as far as Arezzo a second lake was formed, whose waters flowed into the aforesaid lake, closed off around where we see Girone today, and covered all of the aforesaid upper valley, extending for 40 miles. This valley receives over its floor all of the soil brought by the turbid water, as can still be seen at the foot of Prato Magno, which remains very high where the rivers have not consumed it; and in the midst of this land can be seen the deep gorges of rivers that have passed this way, flowing down from the great mountain of Prato Magno: in whose gorges can be found no trace of fossil shells or of soil (bluish like) that of the sea. This lake was conjoined to the lake of Perugia…

A great quantity of fossil shells can be seen where the rivers flow into the sea, because in those places the water is not very salty, being mixed with the fresh water flowing into it; and signs of this can be seen there where in ancient times the Apennine mountains poured their rivers into the Adriano [Adriatic] sea, which in great part show amidst the mountains great quantities of fossil shells along with the bluish soil of the sea; and all of the stones quarried from that place are full of fossil shells.

The Arno is known to have done the same, when it fell from the Golfolina boulder into the sea, after which it was not very low, because in those days its height exceeded that of San Miniato al Tedesco, on whose highest peak appear cliffs with walls full of fossil shells and oysters; the fossil shells do not extend as far as Val di Nievole because the fresh water of the Arno was abundant there […]» (f. 9A – 9r).

«[…] Found under ground, and under the deep cavities of the slabs of stone, the wood of the sawn beams, already blackened, which were found in my time around Castel Fiorentino; and they sank deep in that place, before the current of the Arno could throw them into the sea that covered this area, and were abandoned at this height, before the plains of Casentino were so far lowered by the soil continuously carried away from them by the Arno [...]» (f . 9B – 9v).