latitude and longitude, the Universal Transverse Mercator (UTM) system, and
other grid patterns used today.
Religion often motivated early European mapmakers and others, who sought to
spatially locate not only known points but also identify the location of places from
scripture. Furthermore, locations having great religious significance figured
prominently on maps and were often represented at the center of the illustration,
with all other points clustered around them. The classic example of such a map
is the “T and O” map drawn by European cartographers of the Middle Ages. These
maps represented the world as it was known to the Europeans, with the Mediterra-
nean Sea forming the “T” portion of the map, which divided the depicted land
masses of Europe, Africa, and Asia. Jerusalem or Rome was generally located at
the center of these maps, which, unlike modern maps, were not oriented with north
at the top of the map, but rather east. The Garden of Eden was also frequently
included on T and O maps, usually placed somewhere on the Asian continent. This
cartography was not very useful for navigation or other practical purposes, but
nevertheless illustrates the continued desire of humanity to visually represent the
world, even in the face of widespread geographic ignorance.
By the late Middle Ages, exploration, an activity humans pursued instinctively,
demanded a visual guide whenever possible. The advent of oceangoing travel and
trade required an accurate record of landmarks and hazards for mariners, who
needed to retrace the journeys they had survived either for conquest or maintaining
trade. Such early ships’ logs were simply written commentaries, but these were
eventually replaced by charts that contained both written and visual details. Called
portolan maps, from the Italian wordportolano(port chart), these maps represented
a major step forward for cartography. Such maps frequently featured a crude grid,
based on “rhumb lines,” that provided some basis for calculating distance. Although
not particularly useful for navigating large distances across open water, portolan
maps could be utilized in smaller bodies of water, especially the Mediterranean
Sea, where they were frequently employed by merchants and traders. Cartographers
of a few centuries later, like Gerardus Mercator, would use the portolan charts and
much of Ptolemy’s work as starting points for much more detailed and useful naut-
ical maps, opening the way for modern cartographic techniques. The projection of
the surface of the earth that Mercator developed in the 1500s remains widely used
today in nautical and aeronautical navigation.
The advent of the printing press, the development of new techniques for gather-
ing spatial data, and the discovery of the New World at the end of the 15th century
heralded a flowering of cartographic expansion. As new lands were discovered,
conquered, and settled, the need for maps increased dramatically. Cartographers
became not only recorders of spatial databut also agents of political and social
Cartography 49