Portolans have been a topic of scholarly controversy for decades. The predecessors of the charts is the theme of myriad scholarly works, with myriad theories regarding antecedents. Another issue often addressed is the paucity of charts which are known to exist at this time.
Our blogs about portolan charts address the first topic in very general terms, as the controversies regarding the lineage of them are extensive and ongoing. Serious research is dependent not only on evaluation of the extant examples, but also on knowledge of ancient texts written by early geographers and historians referencing maps and their use. We can say with certainty that extant portolan charts were all drawn with ink on vellum. The paucity of charts has been attributed by some academics to the value of vellum, which is animal skin painstakingly prepared for writing. It was an expensive writing material and not wasted, was used and reused to the extent possible.
In addition to charts which were damaged on board ships, there would have been those which became outdated and the vellum reused for myriad other purposes. Outdated information could be scraped from the skin and new information drawn or written, sometimes creating layers of information. Such manuscripts are known by the term which describes the erasure process – palimpsest. Remnants of the information initially drawn or written on the vellum are often still visible and with modern technology, decipherable. Many scholars believe that thousands of the charts had to have been produced, but as they were used at sea, they went down with ships, got wet and thus damaged, or became outdated and were scraped clean to be used again.
Fourteenth Century Portolan Charts
Portolan charts from the 14th century represent a significant development in the cartographic traditions of medieval Europe. These charts, meticulously drawn and rich in detail, were primarily used for maritime navigation, but in the 14th century they began to increasingly include information of inland import, along with imaginative illustrations and geographical descriptions. This blog discusses one of the better known charts dating to the fourteenth century, the Cortona Chart, as we continue our discussion of portolans and their role in the development of cartographic representations of land and sea.
More than mere navigational tools, portolan charts provide an idea of Medieval Eurocentric worldviews. Their significance lies not only in their age, but also in their representation of European geographical knowledge just prior to the Age of Discovery. The charts provide valuable insights into medieval maritime trade, navigation and cultural exchange.
While the earliest known portolan chart, the Carte Pisane, is as of yet the lone known survivor of the thirteenth century, there are a number of known extant charts dating to the fourteenth century. The remarkable Cortona Chart is one of the world’s earliest surviving nautical charts. Discovered in 1957, its current accepted date of compilation is around 1300, just a few years later than the Carte Pisane. As with the Carte Pisane, its artistic elements are also subdued, in order to prioritize functional navigational details. The coastal lines created by the names on the chart render it remarkably easy to read. The white portion in the image below indicates portions of vellum which were lost in the past, before the modern discovery of the chart.
The Cortona Chart, circa 1300
This superb chart is similar to its predecessor, the Carte Pisane, but is slightly divergent in the areas it depicts. The Cortona charts with truly remarkable accuracy the coasts of the Mediterranean from just west of Sicily, and the Black Sea in its entirety. The Carte Pisane also charts the Medterranean, but in the Black Sea region charts only a portion of the Crimea. The Cortona shows the Levant with toponyms and extends from the Mediterranean to the Black Sea with toponyms along the way through the Greek islands in the Aegean, the Strait of Dardanelles, the Sea of Marmara, and the Strait of Bosphorus, which splits Constantinople (modern Istanbul) into its European and Anatolian sides.
Toponyms abound along both the east and west coast of the Aegean, illustrating the maker's knowledge of the proliferation of ports in antiquity in the region. Though many of these ports silted up centuries before the chart was drawn, its author chose to include them, no doubt due to their former importance to maritime commerce. Remarkably, the chart includes inland features, most notably the entire length of the Danube River. This inclusion not only highlights the cartographer's extensive knowledge but also the ambition to provide a more comprehensive depiction of the region.
The Cortona Chart, or Carta di Cortona, is one of the earliest known manuscript charts in the process of cartographical evolution, representing significant development in the blossoming science of graphic depiction of the planet in cartographic form. It is housed today in the Biblioteca dell'Accademia Etrusca in Cortona, Italy.