131
chapter 7
Basics of symbolization
Cartography is about representation.
—A
lan
M. M
ac
E
achren
,
How
Maps Work (1995)
Maps are a form of graphic communication that like
other graphic forms convey
meaning primarily by symbols. Symbols are the graphic language of maps; the selec-
tion and design of symbols are a major part of creating a successful map.
To represent spatial concepts, relationships, and distributions, such as the pat-
tern of population density in the United States, in words is extremely cumbersome
and
generally ineffective; the reader simply cannot grasp
the relationship between
area and distribution. A verbal description must be read in linear fashion; that is, a
sentence must be read from start to finish to make sense, not from the middle out-
ward. But a map can be read in any order and still be understood. In fact, with a
simple map, the meaning can be assimilated almost instantly.
Since many thematic data are statistical, it might seem that a tabular array of sta-
tistics would display the data just as effectively as a map, but as Table 7.1 and Figure
7.1 show, a table, like a verbal description, cannot convey a map’s spatial component.
Even if numerical data are displayed on a map in their correct geographic arrange-
ment, the reader will not receive the immediate impression of relationships that a map
with appropriate symbols provides.
Cartography is not the only discipline that uses symbols. Mathematicians and
musicians use symbolic notation that can be understood by others in their field any-
where in the world. Some have suggested that maps, because of their symbolic nature,
are a form of universal language. This suggestion has only limited validity, however,
because there is no standardized system of symbols for thematic maps. Such systems
have been proposed, but it appears that the adoption of any one system is unlikely to
occur in the near future. There is a degree of standardization for topographic maps—
contour lines are used for elevations, and many other symbols are common to maps of
various countries. Thus, while the maps may have a somewhat different appearance
132 sYMBOLizaTiOn
overall, a user can read a Swiss, a German, an English, or an American topographic
map with little difficulty. There are standard symbol sets for certain other series of
maps; for example, there has been some recent work on standardizing symbols for
emergency response maps that could be understood by readers of any background.
Maps are a complex form of symbolic communication. Some study and effort are
needed by the map reader to become fluent in the graphic language. Understanding
international traffic signs, which are essentially pictographs, requires only a single
level of perception. One need only recognize the symbol to know its meaning—Stop!,
