978

The origin of the sand in rivers.

All the torrents of water flowing from the mountains to the sea carry with them the stones from the hills to the sea, and by the influx of the sea-water towards the mountains; these stones were thrown back towards the mountains, and as the waters rose and retired, the stones were tossed about by it and in rolling, their angles hit together; then as the parts, which least resisted the blows, were worn off, the stones ceased to be angular and became round in form, as may be seen on the banks of the Elsa. And those remained larger which were less removed from their native spot; and they became smaller, the farther they were carried from that place, so that in the process they were converted into small pebbles and then into sand and at last into mud. After the sea had receded from the mountains the brine left by the sea with other humours of the earth made a concretion of these pebbles and this sand, so that the pebbles were converted into rock and the sand into tufa. And of this we see an example in the Adda where it issues from the mountains of Como and in the Ticino, the Adige and the Oglio coming from the German Alps, and in the Arno at Monte Albano [Footnote 13: At the foot of Monte Albano lies Vinci, the birth place of Leonardo. Opposite, on the other bank of the Arno, is Monte Lupo.], near Monte Lupo and Capraia where the rocks, which are very large, are all of conglomerated pebbles of various kinds and colours.

V.

ON MOUNTAINS.

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

Notebooks of Leonoardo da Vinci
XVI: Physical Geography.
. . .
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,
998
. . .