Notebooks of Leonardo da Vinci

towards the North; where they cut through the strata in the living
stone in the higher parts of the mountains; and, where they join the
plains, these strata are all of potter's clay; as is to be seen in
the valley of Lamona where the river Lamona, as it issues from the
Appenines, does these things on its banks. 

That the rivers have all cut and divided the mountains of the great
Alps one from the other. This is visible in the order of the
stratified rocks, because from the summits of the banks, down to the
river the correspondence of the strata in the rocks is visible on
either side of the river. That the stratified stones of the
mountains are all layers of clay, deposited one above the other by
the various floods of the rivers. That the different size of the
strata is caused by the difference in the floods--that is to say
greater or lesser floods. 

981. 

The summits of mountains for a long time rise constantly. 

The opposite sides of the mountains always approach each other
below; the depths of the valleys which are above the sphere of the
waters are in the course of time constantly getting nearer to the
centre of the world. 

In an equal period, the valleys sink much more than the mountains
rise. 

The bases of the mountains always come closer together. 

In proportion as the valleys become deeper, the more quickly are
their sides worn away. 

982. 

In every concavity at the summit of the mountains we shall always
find the divisions of the strata in the rocks. 

983. 

OF THE SEA WHICH ENCIRCLES THE EARTH. 

I find that of old, the state of the earth was that its plains were
all covered up and hidden by salt water. [Footnote: This passage has
already been published by Dr. M. JORDAN: _Das Malerbuch des L. da
Vinci, Leipzig_ 1873, p. 86. However, his reading of the text
differs from mine.] 

The authorities for the study of the structure of the earth. 

984. 

Since things are much more ancient than letters, it is no marvel if,
in our day, no records exist of these seas having covered so many
countries; and if, moreover, some records had existed, war and
conflagrations, the deluge of waters, the changes of languages and
of laws have consumed every thing ancient. But sufficient for us is
the testimony of things created in the salt waters, and found again
in high mountains far from the seas. 

VI. 

GEOLOGICAL PROBLEMS. 

985. 

In this work you have first to prove that the shells at a thousand
braccia of elevation were not carried there by the deluge, because
they are seen to be all at one level, and many mountains are seen to
be above that level; and to inquire whether the deluge was caused by
rain or by the swelling of the sea; and then you must show how,
neither by rain nor by swelling of the rivers, nor by the overflow
of this sea, could the shells--being heavy objects--be floated up
the mountains by the sea, nor have carried there by the rivers
against the course of their waters. 

Doubts about the deluge. 

986. 

A DOUBTFUL POINT. 

Here a doubt arises, and that is: whether the deluge, which happened
at the time of Noah, was universal or not. And it would seem not,
for the reasons now to be given: We have it in the Bible that this
deluge lasted 40 days and 40 nights of incessant and universal rain,
and that this rain rose to ten cubits above the highest mountains in
the world. And if it had been that the rain was universal, it would
have covered our globe which is spherical in form. And this
spherical surface is equally distant in every part, from the centre
of its sphere; hence the sphere of the waters being under the same
conditions, it is impossible that the water upon it should move,
because water, in itself, does not move unless it falls; therefore
how could the waters of such a deluge depart, if it is proved that
it has no motion? and if it departed how could it move unless it
went upwards? Here, then, natural reasons are wanting; hence to
remove this doubt it is necessary to call in a miracle to aid us, or
else to say that all this water was evaporated by the heat of the
sun.