This sketch of the Fontaine de Vaucluse appeared in a manuscript version of Pliny's Natural History that Petrarch purchased about 1350. In the late nineteenth century, Pierre de Nolhac and others published this sketch and attributed it to Petrarch. It was widely reproduced as representing Petrarch's position as the "first modern man." More recent scholars attribute the sketch to Giovanni Boccaccio and the inscription--Transalpina solitudo mea jocundissima--to Petrarch. The original manuscript in in the Bibliothèque nationale de France.
Source: This image was published in Pierre de Nolhac, Pétrarque et l'humanisme, 2 vols., (Paris, 1907), vol. 2, p. 269: http://books.google.com/books?id=xSfvy4a-sLcC&pg=PA268-IA3 .
Petrarch, Mont Ventoux, Fontaine de Vaucluse, Boccaccio