OF THE DELUGE AND OF MARINE SHELLS.

If you were to say that the shells which are to be seen within the
confines of Italy now, in our days, far from the sea and at such
heights, had been brought there by the deluge which left them there,
I should answer that if you believe that this deluge rose 7 cubits
above the highest mountains-- as he who measured it has
written--these shells, which always live near the sea-shore, should
have been left on the mountains; and not such a little way from the
foot of the mountains; nor all at one level, nor in layers upon
layers. And if you were to say that these shells are desirous of
remaining near to the margin of the sea, and that, as it rose in
height, the shells quitted their first home, and followed the
increase of the waters up to their highest level; to this I answer,
that the cockle is an animal of not more rapid movement than the
snail is out of water, or even somewhat slower; because it does not
swim, on the contrary it makes a furrow in the sand by means of its
sides, and in this furrow it will travel each day from 3 to 4
braccia; therefore this creature, with so slow a motion, could not
have travelled from the Adriatic sea as far as Monferrato in
Lombardy [Footnote: _Monferrato di Lombardia_. The range of hills of
Monferrato is in Piedmont, and Casale di Monferrato belonged, in
Leonardo's time, to the Marchese di Mantova.], which is 250 miles
distance, in 40 days; which he has said who took account of the
time. And if you say that the waves carried them there, by their
gravity they could not move, excepting at the bottom. And if you
will not grant me this, confess at least that they would have to
stay at the summits of the highest mountains, in the lakes which are
enclosed among the mountains, like the lakes of Lario, or of Como
and il Maggiore [Footnote: _Lago di Lario._ Lacus Larius was the
name given by the Romans to the lake of Como. It is evident that it
is here a slip of the pen since the the words in the MS. are: _"Come
Lago di Lario o'l Magare e di Como,"_ In the MS. after line 16 we
come upon a digression treating of the weight of water; this has
here been omitted. It is 11 lines long.] and of Fiesole, and of
Perugia, and others.

And if you should say that the shells were carried by the waves,
being empty and dead, I say that where the dead went they were not
far removed from the living; for in these mountains living ones are
found, which are recognisable by the shells being in pairs; and they
are in a layer where there are no dead ones; and a little higher up
they are found, where they were thrown by the waves, all the dead
ones with their shells separated, near to where the rivers fell into
the sea, to a great depth; like the Arno which fell from the
Gonfolina near to Monte Lupo [Footnote: _Monte Lupo_, compare 970,
13; it is between Empoli and Florence.], where it left a deposit of
gravel which may still be seen, and which has agglomerated; and of
stones of various districts, natures, and colours and hardness,
making one single conglomerate. And a little beyond the sandstone
conglomerate a tufa has been formed, where it turned towards Castel
Florentino; farther on, the mud was deposited in which the shells
lived, and which rose in layers according to the levels at which the
turbid Arno flowed into that sea. And from time to time the bottom
of the sea was raised, depositing these shells in layers, as may be
seen in the cutting at Colle Gonzoli, laid open by the Arno which is
wearing away the base of it; in which cutting the said layers of
shells are very plainly to be seen in clay of a bluish colour, and
various marine objects are found there. And if the earth of our
hemisphere is indeed raised by so much higher than it used to be, it
must have become by so much lighter by the waters which it lost
through the rift between Gibraltar and Ceuta; and all the more the
higher it rose, because the weight of the waters which were thus
lost would be added to the earth in the other hemisphere. And if the
shells had been carried by the muddy deluge they would have been
mixed up, and separated from each other amidst the mud, and not in
regular steps and layers-- as we see them now in our time.

The marine shells were not produced away from the sea.