Portolan Charts Quotes

“Even if we admit that running-survey and compass techniques were somehow being used on ships to produce sea-charts as early as the thirteenth century (which most historians of science would rule out) we still come against the unexplained enigma of the miraculous and fully formed de novo appearance of the Carta Pisane. As we've seen, not a single chart pre-dates it that demonstrates in any way the gradual build-up of coastal profiles across the whole extent of the Mediterranean that must have occurred before a likeness as perfect as this could have been resolved.
It is possible, of course, through the vicissitudes of history, that all the evidence for the prior evolution of portolans before the Carta Pisane has simply been lost. If that were the case, however -- in other words if the Carta Pisane is a snapshot of a certain moment in the development of an evolving genre of maps, and if we accept that all earlier 'snap-shots' have been lost, wouldn't we nevertheless expect that such an 'evolving genre' would have continued to evolve after the date of the earliest surviving example?
Whether we set the date of the Pisane between 1270 and 1290 [...] or a little later -- between 1295 and 1300 -- as other scholars have argued, we've seen that there was no significant evolution afterwards.
Now kept in the Bibliothèque Nationale in Paris, the enigmatic Pisane is an unsigned chart and scholars have no idea who the cartographer might have been.”
― Graham Hancock, Underworld: The Mysterious Origins of Civilization

“The light-shaded Porcupine Bank can easily be seen directly west of Ireland, in exactly the same place, and roughly the same size, as the legendary Hy-Brasil on the portolan charts. The entire bank lies between 40 and 200 metres beneath the surface, and most of it (probably more than 600 square kilometres) would have been exposed at the Last Glacial Maximum, 21,000 years ago.”
― Graham Hancock, Underworld: The Mysterious Origins of Civilization