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The Universe

where the Danube flows today. And the evidence of this is shown by the oysters and cockle shells, and scallops and bones of great fishes which are still found in many places in the high slopes of those mountains; and this sea was formed by the filling up of the spurs of the Adula range which extended to the east, and joined the spurs of the Taurus range extending to the west. And near Bithynia the waters of this Black Sea poured into the Propontis falling into the Aegean Sea, that is the Mediterranean Sea, where at the end of a long course the spurs of the Adula range were separated from those of the Taurus range; and the Black Sea sank down and laid bare the valley of the Danube with the above-named provinces, and the whole of Asia Minor beyond the Taurus range to the north, and the plain that stretches from Mount Caucasus to the Black Sea to the west, and the plain of the Don this side of the Ural Mountains, that is at their feet. So the Black Sea must have sunk about 1,000 braccia to uncover such vast plains.44 It is not denied that the Nile is always turbid as it enters the Egyptian Sea and that this turbidness is caused by the soil that this river carries away continually from the places through which it passes; which soil never returns back, nor does the sea receive it except it throws it on its shores. Behold the ocean of sand beyond Mount Atlas where it was once covered with salt water.45 How the river Po in a short time might dry up the Adriatic Sea in the same way as it has dried up a large part of Lombardy.46

3. water and air Write how the clouds are formed and how they dissolve, and what it is that causes vapour to rise from the water of the earth into the air, and the causes of mists and of the air becoming thickened, and why it appears more blue or less blue at one time than at another; and describe also the regions of the air, and the cause of snow and hail, and how water

Leonardo da vinci  
Leonardo da vinci