James S. Aber
What is a Map?
A map is a graphic representation or scale model of spatial concepts. It is a means for conveying geographic information. Maps are a universal medium for communication, easily understood and appreciated by most people, regardless of language or culture. Incorporated in a map is the understanding that it is a “snapshot” of an idea, a single picture, a selection of concepts from a constantly changing database of geographic information (Merriam 1996).
Old maps provide much information about what was known in times past, as well as the philosophy and cultural basis of the map, which were often much different from modern cartography. Maps are one means by which scientists distribute their ideas and pass them on to future generations (Merriam 1996).
Cartography is the art and science of making maps. The oldest known maps are preserved on Babylonian clay tablets from about 2300 B.C. Cartography was considerably advanced in ancient Greece. The concept of a spherical Earth was well known among Greek philosophers by the time of Aristotle (ca. 350 B.C.) and has been accepted by all geographers since.
Greek and Roman cartography reached a culmination with Claudius Ptolemaeus (Ptolemy, about A.D. 85-165). His “world map” depicted the Old World from about 60°N to 30°S latitudes. He wrote a monumental work, Guide to Geography (Geographike hyphygesis), which remained an authorative reference on world geography until the Renaissance.
During the Medieval period, European maps were dominated by religious views. The T-O map was common. In this map format, Jerusalem was depicted at the center and east was oriented toward the map top. Viking explorations in the North Atlantic gradually were incorporated into the world view beginning in the 12th century. Meanwhile, cartography developed along more practical and realistic lines in Arabic lands, including the Mediterranean region. All maps were, of course, drawn and illuminated by hand, which made the distribution of maps extremely limited.
The invention of printing made maps much more widely available beginning in the 15th century. Maps were at first printed using carved wooden blocks (see above). Among the most important map makers of this period was Sebastian Münster in Basel (now Switzerland). His Geographia, published in 1540, became the new global standard for maps of the world.
Printing with engraved copper plates appeared in the 16th century and continued to be the standard until photographic techniques were developed. Major advances in cartography took place during the Age of Exploration in the 15th and 16th centuries. Map makers responded with navigation charts, which depicted coast lines, islands, rivers, harbors, and features of sailing interest. Compass lines and other navigation aids were included, new map projections were devised, and globes were constructed. Such maps and globes were held in great value for economic, military, and diplomatic purposes, and so were often treated as national or commercial secrets–classified or proprietary maps.
The first whole-world maps began to appear in the early 16th century, following voyages by Columbus and others to the New World. The first true world map is generally credited to Martin Waldseemüller in 1507. This map utilized an expanded Ptolemaic projection and was the first map to use the name America for the New World–see Waldseemüller’s world map.
Gerardus Mercator of Flanders (Belgium) was the leading cartographer of the mid-16th century. He developed a cylindrical projection that is still widely used for navigation charts and global maps. He published a map of the world in 1569 based on this projection. Many other map projections were soon developed.
Maps became increasingly accurate and factual during the 17th, 18th and 19th centuries with the application of scientific methods. Many countries undertook national mapping programs. Nonetheless, much of the world was poorly known until the widespread use of aerial photography following World War I. Modern cartography is based on a combination of ground observations and remote sensing.
Geographic information systems (GIS) emerged in the 1970-80s period. GIS represents a major shift in the cartography paradigm. In traditional (paper) cartography, the map was both the database and the display of geographic information. For GIS, the database, analysis, and display are physically and conceptually separate aspects of handling geographic data. Geographic information systems comprise computer hardware, software, digital data, people, organizations, and institutions for collecting, storing, analyzing, and displaying georeferenced information about the Earth (Nyerges 1993).
What is a Map?
Are maps realistic representations of the actual world? No–never! Field measurements are subject to errors of accuracy and precision. Aerial photographs and satellite images portray only certain portions of the light spectrum, as filtered through the atmosphere and detection instruments. No map can depict all physical, biological, and cultural features for even the smallest area. A map can display only a few selected features, which are portrayed usually in highly symbolic styles according to some kind of classification scheme. In these ways, all maps are estimations, generalizations, and interpretations of true geographic conditions.
All maps are made according to certain basic assumptions, for example sea-level datum, which are not always true or verifiable. Finally any map is the product of human endeavor, and as such may be subject to unwitting errors, misrepresentation, bias, or outright fraud. In spite of these limitations, maps have proven to be remarkably adaptable and useful through several millennia of human civilization. Maps of all kinds are fundamentally important for modern society.The fool’s cap world map, about 1590. Ptolemaic projection on the face of a jester. Maker, date, and place of publication are unknown. Maps are human representations of the world, as seen through the eyes of a clown in this example. Widely reproduced to depict the human element of cartography. Image adapted from Dalhousie University, Canada.
Merriam, D.F. 1996. Kansas 19th century geologic maps. Kansas Academy of Science, Transactions 99, p. 95-114.
Nyerges, T.L. 1993. Understanding the scope of GIS: Its relationship to environmental modeling. In Goodchild, M.F., Parks, B.O. and Steyaert, L.T. (eds.), Environmental modeling with GIS, p. 75-93. Oxford Univ. Press, 488 p.