11. I explained in 2011 at the " Portolan chart " talk page here the purpose of my pages: 12. The production of medieval Portolan charts can be divided in two major schools : the Italian and the Catalan. 13. The island makes its first explicit appearance as a large rectangular island in the 1424 portolan chart of Zuane Pizzigano. 14. With each sheet at 11 cm x 16 cm, making it the smallest portolan chart from the period still extant. 15. The wealth of detail contained in portolano handbooks is reflected in the portolan charts , stunningly accurate even by modern standards. 16. Course of the " River of Gold " ( Senegal-Niger ) in the 1413 portolan chart of Mecia de Viladestes. 17. Trickett claims that the French Vallard maps were composed of several portolan charts that were incorrectly assembled from now lost Portuguese charts. 18. Nordenskiold ), the Majorcans were responsible for the invention ( c . 1300 ) of the " normal portolan chart ". 19. Both Majorca and Genoa have laid claim for the invention of the portolan chart , and it is unlikely this will ever be resolved. 20. I ran across a collection of articles on medieval portolan charts being kept in this user's userspace here : User : Portolanero.
