How do you map something that might not be real? The problem for European map-makers such as Mercator (who seldom left Duisburg) was who and what to believe when sifting through travel accounts and maps containing fresh information, which had often been received at second or third hand. Does the lake/mountain/river go on the map or not? This instalment of How To Read Maps deals with the vexed question of mythical lakes.
The mother and father of all mythical lakes are Zaire and Zaflan, described as the source of the Nile by Ptolemy in 2nd century CE Alexandria and included in many western printed maps of Africa until the mid 19th century as there was nothing better to go on. Our illustration is of Mercator’s version, and our example was printed in 1607, almost 1450 years after Ptolemy’s death. Were the twin lakes wholly mythical? The Nile does, more or less, rise in a very big lake, but it is a fair guess that a whole continent will have a lake or two on it somewhere. Ptolemy’s known source was Marinus of Tyre, who relayed the account of a Greek merchant named Diogenes. He claimed to have travelled inland from the east African coast for 25 days before stumbling across two great lakes fed by melting snow from ‘the mountains of the Moon’. Perhaps Diogenes really had seen Lake Victoria in 110 CE. As Ptolemy was writing in Alexandria, I’ve often wondered what other sources, now lost, he might have had access to. Pure speculation, but with so much depending on the rise and fall of the Nile it seems almost inconceivable to me that the Egyptians themselves made no attempt to trace its source.
Our next map is of ‘Lake Parime’ in Guyana in the northeastern tip of South America, shown on a Dutch map by Blaeu. Walter Raleigh explored (and raided) the region in 1595 in search of el Dorado. He didn’t find it, and it was in his best interests to beef up his discoveries when he returned to England, (although it was his second expedition to the region in 1617 which led to his beheading). 17th and 18th century maps modelled on Raleigh’s discoveries typically show a huge ‘mythical’ lake, as here, with the mythical city of Manoa, or el Dorado, on its shores. Long assumed to be entirely fictitious, geologists have now discovered traces of a great extinct lake in neighbouring Roraima, Brazil. Slowly draining away, it disappeared before it could be mapped by later explorers, but Raleigh might well have been describing what he saw.
Finally, a lake which we know is there, the Great Salt Lake in modern Utah. This map was published by the Society for the Diffusion of Useful Knowledge in 1842, just before the Mexican-American War which saw the poorly mapped region of Upper California become part of the United States. Compare it with a detail from Willem Blaeu’s map of the Americas engraved in 1617, which shows a large lake in New Mexico surrounded by the seven legendary cities of Cibola – the cities of gold. It’s based on early Spanish accounts and the cities never existed, but is the lake a lucky guess or Chinese whispers of the Great Salt Lake?