The Da Vinci Notebooks at sacred-texts.com
And of these I found some in the rocks of the high Appenines and mostly at the rock of La Vernia. 581
247:581 6: Sasso della Vernia. The frowning rock between the sources of the Arno and the Tiber, as Dante describes this mountain, which is 1269 metres in height.
This note is written by the side of that given as No. 1020; but their connection does not make it clear what Leonardo's purpose was in writing it.