Perhaps the most famous geographic myth is California shown as an island. The earliest maps of North America showed California as a peninsula, based on the reports of Francisco de Ulloa who explored the Bay of California in 1539. The famous maps by Gerard Mercator and Abraham Ortelius showed a correct depiction of California in the late sixteenth century, but that was to change early in the following century.
In 1602, Sebastian Vizcaino sailed up the California coast, and Father Antonio de la Ascension wrote a journal of the voyage. Ascension claimed that California was separated from the American continent by the “mediterranean Sea of California.” It is not clear where Ascension got this notion, but this claim led to the mapping of California as an island beginning in 1622 with a small map on the title page of Antonio de Herrera’s Descripcion de las Indias Occidentales. The first folio maps to show this myth were by Abraham Goos in 1624 and by Henry Briggs in 1625. However, it wasn’t until the more important commercial publishers accepted the insularity of California that this notion achieved universal acceptance. The first of these influential insular renderings was by British cartographer John Speed in 1626, followed by the Dutch publishers, su as Jan Jansson, whose map of North America from 1636. These were soon followed by all other major publishers such as Nicolas Sanson, Guillaume Blaeu, Pierre Duval, and Herman Moll.
California was depicted on maps as an island for over 100 years, even after Father Kino established its penisularity about 1705. Beginning with Delisle’s map of America in 1722, some cartographers began again to show a peninsular California, but many cartographers continued to depict it as an island. Finally in 1747, Ferdinand VII of Spain issued a royal edict declaring California as part of the mainland, and soon after that insular California finally disappeared from the map.