Against the idea that the stars made shells in the mountains
Leonardo challenges the astrological theory of fossils with the evidence of gravel, leaves and sea plants
A page of text, without diagrams, in which Leonardo argues against those who claim that the shells found in mountains were produced there by the influence of the constellations. He asks how the stars could make shells of many sizes, ages and kinds in one place, and how they could account for gravel congealed at different heights, brought from distant lands by rivers and worn round by long tumbling. He extends the challenge to the great number of fossilised leaves, seaweed and broken sea crabs found petrified together with shells and sand.
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The constellations cannot explain shells of every size and age
If shells were produced in the mountains by the constellations, how could such influence make shells of various sizes, different ages and various kinds all in one and the same place? Leonardo poses the question as a direct challenge to the astrological account of fossils.
Gravel, leaves and sea creatures as evidence of flooding
He asks how the stars could congeal gravel at different heights of the high mountains, gravel being pieces of stone that lost their corners through long tumbling in river currents that carried it from distant lands. He adds the vast number of fossil leaves and seaweed, and sea crabs broken into separate pieces and interposed among the shells and sand.