977

The origin of the sand in rivers.

A river that flows from mountains deposits a great quantity of large stones in its bed, which still have some of their angles and sides, and in the course of its flow it carries down smaller stones with the angles more worn; that is to say the large stones become smaller. And farther on it deposits coarse gravel and then smaller, and as it proceeds this becomes coarse sand and then finer, and going on thus the water, turbid with sand and gravel, joins the sea; and the sand settles on the sea-shores, being cast up by the salt waves; and there results the sand of so fine a nature as to seem almost like water, and it will not stop on the shores of the sea but returns by reason of its lightness, because it was originally formed of rotten leaves and other very light things. Still, being almost—as was said—of the nature of water itself, it afterwards, when the weather is calm, settles and becomes solid at the bottom of the sea, where by its fineness it becomes compact and by its smoothness resists the waves which glide over it; and in this shells are found; and this is white earth, fit for pottery.

Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.

Notebooks of Leonoardo da Vinci
XVI: Physical Geography.
. . .
957,
958,
959,
960
Theory of the circulation of the waters.
961,
962
Observations in support of the hypothesis.
963,
964,
965,
966,
967,
968,
969
On the way in which the sources of rivers are fed.
970
The tide in estuaries.
971
confluence.
972,
973,
974
Whirlpools.
975
On the alterations in the channels of rivers.
976
The origin of the sand in rivers.
977,
978
The formation of mountains.
979,
980,
981,
982,
983
The authorities for the study of the structure of the earth.
984,
985
Doubts about the deluge.
986
That marine shells could not go up the mountains.
987
The marine shells were not produced away from the sea.
988
Further researches.
989,
990,
991
Other problems.
992,
993,
994
Constituents of the atmosphere.
995
On the motion of air.
996,
997
. . .