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especially suited for portraying a particular
kind of geographical variation. For example,
hue, related to wavelength of visible light and
often associated with named colours such as
red and green, is appropriate for representing
qualitative differences among, for example,
various categories of land use. Bertin’s ration-
ale was straightforward: because red, green,
and yellow look different to persons with nor-
mal color vision, they are ideal for mapping
differences in kind, especially for area features
large enough to require discernible patches of
hue. Similarly, readily recognized differences
in form among point and line symbols make
shape an appropriate visual variable when a
map must distinguish churches from schools
and footpaths from railways. By contrast,
quantitative data are better represented with
symbols that vary in size or greytone value;
that is, relative darkness. Viewers are well serv-
ed by map authors who distinguish between
count or magnitude data such as total popula-
tion or number of employees, and intensity data
such as population density or the proportion of
the labour force unemployed. With count data,
for example, point symbols that vary in size
support a logical larger-means-more metaphor
that promotes comparisons without looking
repeatedly at the map key, whereas for intensity
data symbols ranging from white to black sup-
port an equally obvious darker-means-more
decoding rule (Monmonier, 2005). Although
symbols that vary in direction are logical
for representing phenomena such as wind direc-
tion and one-way streets, pattern variation is
largely limited to dashed-line symbols and area
symbols, such as the arrays of dots that
connote orchard land and vineyards on
topographic maps. Dynamic cartography has
produced additional visual variables, notably
the duration, rate of change and order of
scenes (DiBiase, MacEachren, Krygier and
Reeves, 1992).
Because place and feature names use nat-
ural language to link cartographic symbols to
specific locations, typography is another
important part of the map’s symbolic code
(Wood, 2000). And because type comes in
various shapes and sizes, map labels reflect
conventions such as the use of italic type for
hydrographic features as well as an extension
of Bertin’s theory of retinal variables. Although
aesthetic dictates that map authors avoid using
numerous typefaces to represent qualitative
differences among places or features, style
variations (roman/italic, all-uppercase/initial
capitals, bold/plain, underlining) support the
typographical coding of differences in kind,whereas type size affords a readily decoded
representation of magnitude. Some reference
maps use a redundant coding in which the
sizes of point symbols and their labels offer
a mutually reinforced treatment of population
size.
Names on maps can have deep cultural–
political significance, especially when con-
quest or revolution allows the victor to rename
places and geographical features, and even in-
stall a new language or orthography (writing
system). As illustrated by the renaming and re-
renaming of St Petersburg in Russia, control
of a country’s official cartography presents an
irresistible opportunity to underscore the
loser’s defeat by replacing its toponyms
(place names). As pervasive symbols of dom-
ination, names on map and road signs can
arouse resentment as well as inspire alternative
cartographies similar to the Palestinian maps
of Israel, rendered crudely in Arabic atop
photographic copies of official maps
(Kadmon, 2000, pp. 80–1). And because maps
reveal otherwise obscure, pejorative feature
names inherited from earlier, less politically
sensitive times, they can trigger the belated
removal of names (Monmonier, 2006). Recent
disputes over cartographic labels have focused
on waters separating feuding countries (e.g.
Sea of Japan/East Sea, Persian Gulf/Arabian
Gulf), the toponyms and orthography of indi-
genous peoples (e.g. in Hawaii and northern
Canada) and a country’s right to police the
rendering of its name beyond its borders (e.g.
Macedonia and Myanmar, both resisted by the
USA).
Because cartographic scale is usually too
small for an exact treatment of shape and
other geometric relationships, maps are almost
always generalized, even large-scale maps of
small areas (Buttenfield and McMaster,
1991). Cartographic generalization begins
with the selection of features, some of which
represent the phenomenon portrayed while
others provide a frame of reference linking
new information to the viewer’s existing
understanding of the region mapped. For
example, coastlines, nationalboundariesand
highway networks are common frame-of-
reference features on maps not explicitly con-
cerned with coastal geomorphology,geopol-
iticsor transportation. Map authors must
select features carefully, because legibility often
requires line and point symbols proportion-
ately thicker than the features portrayed. For
instance, a road five metres wide represented
on a 1:50,000 map by a barely visible line
one millimetre thick occupies a cartographicGregory / The Dictionary of Human Geography 9781405132879_4_M Final Proof page 436 1.4.2009 3:19pmMAP