Cavities scoured in a riverbed (c, n, m, r)
Depth of hollows and the sorting of sand, gravel and tufa
Around a set of drawn current-forms Leonardo labels points c, n, m and r on a riverbed, noting that the greatest hollow lies at c and that channel m is scoured deeper than n or r. He explains that where much sand lies, gravel or bare tufa is found before and behind it, because sand is dropped facing the escape of the water while gravel is thrown to the sides; as the current slows, sand caps the gravel. He adds that small floods first carry off brushwood, then bury it in sand, and finally, gathering strength, roll in gravel and larger stones. The upper part of the sheet carries pen sketches of streaming, scoured forms accompanying the text.
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Depth of scour at points c, n, m, r
Leonardo marks the riverbed at c, n, m and r, stating that the greatest hollow is found at c and that the channel m is scoured more deeply than n or r. The labels key the text to the current-forms drawn above.
Sand capping gravel over bare tufa
Where much sand lies, gravel or bare tufa is found before and behind it: sand settles facing the water's escape, gravel is cast to the sides, and as the flow slows the sand becomes a lid over the gravel. Small floods first bury brushwood in sand before rolling in gravel and larger stones.
Streaming forms of the scoured bed
The upper third of the sheet is filled with pen sketches of elongated, streaming forms with rounded, hollowed ends. They appear drawn to show how the current scours and shapes the river bottom described in the text.