Introduction to Map Types
Maps can be divided into three main classes,
General Reference Maps
General reference maps are multi purpose maps. Their objective
is to portray the spatial association of diverse geographical
phenomena. Basically, general reference maps show a great deal
of information! They are extremely useful in a variety of situations
and they are the most common map type.
Examples of a General Reference Map are:
General reference maps answer basic questions such as:
Where is one thing in relationship to another?
Where are roads in relationship to urban areas?
Where are recrea tional areas in relationship to major metropolitian
Where are rivers and streams in relationship to elevation
and topographic data?
The list of questions is only limited by the types of information
on the map and the spatial associat ions you can make using
the information presented. Reference maps pay great attention
to accuracy. Positional relationships of the mapped features
are extremely important on this type of map. The location of
roads, rivers, cities and other features are carefully plotted.
Basically, reference maps illustrate a great deal of information
and are used for just what their name indicates: REFERENCE
Thematic maps are d ifferent from general reference maps in that
they focus on one topic or theme. The purpose of a thematic map
is to show how this topic changes or differes from place to place.
Examples of a thematic map are:
Positional accuracy, which is of the highest importance in reference
maps, is less important for a thematic map. It is more important
for the map user to pay a gre at deal of attention to what type
of data was used to create the map and how the data was mapped
on a thematic map. Questions such as, "What is the source
of the data?", "What is the date the data was collected?",
and "How was the data divided into mappable units?"
must be asked by the map user in order to insure that the message
the map is telling is accurate.
Maps designed for navigators are called charts. Simply put, maps
are to be looked at and charts are to be worked on. Routes are
plotted, positions are determined, bearings are marked on charts.
Examples of a chart are:
It needs to be emphasized that you can probably identify
"pure" general reference maps, thematic maps and charts,
but in many cases maps combine functions. For example the green
printing on a topographic map shows the distribution of forested
areas. Therefore topographic maps, deemed a general reference map,
can also be a thematic map showing the distribution of forest areas
in a region. Similarly, a thematic map can show political boundaries,
cities, or rivers so that the map user can easily fix locations
of the subject distribution.