The Notebooks of Leonardo Da Vinci — Complete
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.
988.
As to those who say that shells existed for a long time and were
born at a distance from the sea, from the nature of the place and of
the cycles, which can influence a place to produce such
creatures--to them it may be answered: such an influence could not
place the animals all on one line, except those of the same sort and
age; and not the old with the young, nor some with an operculum and
others without their operculum, nor some broken and others whole,
nor some filled with sea-sand and large and small fragments of other
shells inside the whole shells which remained open; nor the claws of
crabs without the rest of their bodies; nor the shells of other
species stuck on to them like animals which have moved about on
them; since the traces of their track still remain, on the outside,
after the manner of worms in the wood which they ate into. Nor would
there be found among them the bones and teeth of fish which some
call arrows and others serpents' tongues, nor would so many
[Footnote: I. Scilla argued against this hypothesis, which was still
accepted in his days; see: _La vana Speculazione, Napoli_ 1670.]
portions of various animals be found all together if they had not
been thrown on the sea shore. And the deluge cannot have carried
them there, because things that are heavier than water do not float
on the water. But these things could not be at so great a height if
they had not been carried there by the water, such a thing being
impossible from their weight. In places where the valleys have not
been filled with salt sea water shells are never to be seen; as is
plainly visible in the great valley of the Arno above Gonfolina; a
rock formerly united to Monte Albano, in the form of a very high
bank which kept the river pent up, in such a way that before it
could flow into the sea, which was afterwards at its foot, it formed
two great lakes; of which the first was where we now see the city of
Florence together with Prato and Pistoia, and Monte Albano. It
followed the rest of its bank as far as where Serravalle now stands.
>From the Val d'Arno upwards, as far as Arezzo, another lake was
formed, which discharged its waters into the former lake. It was
closed at about the spot where now we see Girone, and occupied the
whole of that valley above for a distance of 40 miles in length.
This valley received on its bottom all the soil brought down by the
turbid waters. And this is still to be seen at the foot of Prato
Magno; it there lies very high where the rivers have not worn it
away. Across this land are to be seen the deep cuts of the rivers
that have passed there, falling from the great mountain of Prato
Magno; in these cuts there are no vestiges of any shells or of
marine soil. This lake was joined with that of Perugia [Footnote:
See PI. CXIII.]
A great quantity of shells are to be seen where the rivers flow into
the sea, because on such shores the waters are not so salt owing to
the admixture of the fresh water, which is poured into it. Evidence
of this is to be seen where, of old, the Appenines poured their
rivers into the Adriatic sea; for there in most places great
quantities of shells are to be found, among the mountains, together
with bluish marine clay; and all the rocks which are torn off in
such places are full of shells. The same may be observed to have
been done by the Arno when it fell from the rock of Gonfolina into
the sea, which was not so very far below; for at that time it was
higher than the top of San Miniato al Tedesco, since at the highest
summit of this the shores may be seen full of shells and oysters
within its flanks. The shells did not extend towards Val di Nievole,
because the fresh waters of the Arno did not extend so far.
That the shells were not carried away from the sea by the deluge,
because the waters which came from the earth although they drew the
sea towards the earth, were those which struck its depths; because
the water which goes down from the earth, has a stronger current
than that of the sea, and in consequence is more powerful, and it
enters beneath the sea water and stirs the depths and carries with
it all sorts of movable objects which are to be found in the earth,
such as the above-mentioned shells and other similar things. And in
proportion as the water which comes from the land is muddier than
sea water it is stronger and heavier than this; therefore I see no
way of getting the said shells so far in land, unless they had been
born there. If you were to tell me that the river Loire [Footnote:
Leonardo has written Era instead of Loera or Loira--perhaps under
the mistaken idea that _Lo_ was an article.],which traverses France
covers when the sea rises more than eighty miles of country, because
it is a district of vast plains, and the sea rises about 20 braccia,
and shells are found in this plain at the distance of 80 miles from
the sea; here I answer that the flow and ebb in our Mediterranean
Sea does not vary so much; for at Genoa it does not rise at all, and
at Venice but little, and very little in Africa; and where it varies
little it covers but little of the country.
The course of the water of a river always rises higher in a place
where the current is impeded; it behaves as it does where it is
reduced in width to pass under the arches of a bridge.
Further researches (989-991).
989.
A CONFUTATION OF THOSE WHO SAY THAT SHELLS MAY HAVE BEEN CARRIED TO
A DISTANCE OF MANY DAYS' JOURNEY FROM THE SEA BY THE DELUGE, WHICH
WAS SO HIGH AS TO BE ABOVE THOSE HEIGHTS.
I say that the deluge could not carry objects, native to the sea, up
to the mountains, unless the sea had already increased so as to
create inundations as high up as those places; and this increase
could not have occurred because it would cause a vacuum; and if you
were to say that the air would rush in there, we have already
concluded that what is heavy cannot remain above what is light,
whence of necessity we must conclude that this deluge was caused by
rain water, so that all these waters ran to the sea, and the sea did
not run up the mountains; and as they ran to the sea, they thrust
the shells from the shore of the sea and did not draw them to wards
themselves. And if you were then to say that the sea, raised by the
rain water, had carried these shells to such a height, we have
already said that things heavier than water cannot rise upon it, but
remain at the bottom of it, and do not move unless by the impact of
the waves. And if you were to say that the waves had carried them to
such high spots, we have proved that the waves in a great depth move
in a contrary direction at the bottom to the motion at the top, and
this is shown by the turbidity of the sea from the earth washed down
near its shores. Anything which is lighter than the water moves with
the waves, and is left on the highest level of the highest margin of
the waves. Anything which is heavier than the water moves, suspended
in it, between the surface and the bottom; and from these two
conclusions, which will be amply proved in their place, we infer
that the waves of the surface cannot convey shells, since they are
heavier than water.
If the deluge had to carry shells three hundred and four hundred
miles from the sea, it would have carried them mixed with various
other natural objects heaped together; and we see at such distances
oysters all together, and sea-snails, and cuttlefish, and all the
other shells which congregate together, all to be found together and
dead; and the solitary shells are found wide apart from each other,
as we may see them on sea-shores every day. And if we find oysters
of very large shells joined together and among them very many which
still have the covering attached, indicating that they were left
here by the sea, and still living when the strait of Gibraltar was
cut through; there are to be seen, in the mountains of Parma and
Piacenza, a multitude of shells and corals, full of holes, and still
sticking to the rocks there. When I was making the great horse for
Milan, a large sack full was brought to me in my workshop by certain
peasants; these were found in that place and among them were many
preserved in their first freshness.
Under ground, and under the foundations of buildings, timbers are
found of wrought beams and already black. Such were found in my time
in those diggings at Castel Fiorentino. And these had been in that
deep place before the sand carried by the Arno into the sea, then
covering the plain, had heen raised to such a height; and before the
plains of Casentino had been so much lowered, by the earth being
constantly carried down from them.
[Footnote: These lines are written in the margin.]
And if you were to say that these shells were created, and were
continually being created in such places by the nature of the spot,
and of the heavens which might have some influence there, such an
opinion cannot exist in a brain of much reason; because here are the
years of their growth, numbered on their shells, and there are large
and small ones to be seen which could not have grown without food,
and could not have fed without motion--and here they could not move
[Footnote: These lines are written in the margin.]
990.
That in the drifts, among one and another, there are still to be
found the traces of the worms which crawled upon them when they were
not yet dry. And all marine clays still contain shells, and the
shells are petrified together with the clay. From their firmness and
unity some persons will have it that these animals were carried up
to places remote from the sea by the deluge. Another sect of
ignorant persons declare that Nature or Heaven created them in these
places by celestial influences, as if in these places we did not
also find the bones of fishes which have taken a long time to grow;
and as if, we could not count, in the shells of cockles and snails,
the years and months of their life, as we do in the horns of bulls
and oxen, and in the branches of plants that have never been cut in
any part. Besides, having proved by these signs the length of their
lives, it is evident, and it must be admitted, that these animals
could not live without moving to fetch their food; and we find in
them no instrument for penetrating the earth or the rock where we
find them enclosed. But how could we find in a large snail shell the
fragments and portions of many other sorts of shells, of various
sorts, if they had not been thrown there, when dead, by the waves of
the sea like the other light objects which it throws on the earth?
Why do we find so many fragments and whole shells between layer and
layer of stone, if this had not formerly been covered on the shore
by a layer of earth thrown up by the sea, and which was afterwards
petrified? And if the deluge before mentioned had carried them to
these parts of the sea, you might find these shells at the boundary
of one drift but not at the boundary between many drifts. We must
also account for the winters of the years during which the sea
multiplied the drifts of sand and mud brought down by the