# Geog 100 on Maps

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6 Nov 2011
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Geography 100; Week 2 – Jan. 11
Synopsis: On Maps, I
Geography: the most map-oriented of all disciplines…
Maps are highly efficient at conveying a sense of patterns/distributions.
They serve as storehouses of information about patterns of things across the earth!
And they can open our eyes to unsuspected relationships...
Maps give us a visual image of reality.
In transforming the world (reality) into a map, three major factors come into play….
Selectivity
The mapmaker processes reality for us.
What to put on the map (what to select) and what to leave out is ultimately a matter of judgment!
That means maps are exercises in communication…
They must avoid the trap of communicating too little and communicating too much…
Examples: unsuccessful communication...
Examples: successful communication...
Henry Beck’s map of the London underground: pruning and selecting.
Conclusion: the map is a selective image of reality:
Symbol
Information on a map can be shown by pictographs or by symbols
Symbols: more or less abstract designs used to represent real phenomena on a map.
A key/legend explains the meaning off the symbols used.
These are the three classes of symbols: point, line, area.
Symbols may show kinds of things or amounts (i.e., they can be qualitative or quantitative).
All told, that yields a matrix of 6 symbol classes...
Principles at work in choosing symbols for maps: resemblance; association; arbitrary choice.
Conclusion: the map is a selective, symbolic image of reality.
Scale
Maps can be drawn at many levels of detail but are always much reduced images of reality.
The degree of reduction is indicated by the map’s scale.
Scale refers to the relationship between dimensions on the map and in the real world….
It is the ratio of any specific distance on the map to the actual corresponding distance on the ground.
The mapmaker reveals a map’s scale in one (or more) of 3 ways...
Verbally: by a written statement….
Visually: by a graphic scale….
Mathematically: by a fraction or ratio….
In any ratio, the numbers presume the same unit of measure, which will not be designated.
A map scale ratio is always expressed as 1 to some number.
We talk of large-scale maps and small-scale maps….
‘Large’ and ‘small’ do not refer to the amount of land shown on the map but to the size of the ratio!
So: 1: 4800 is a large ratio (showing things at a large scale); 1: 2,000,000 is a much smaller scale.
Conclusion: the map is a selective, symbolic image of reality at some greatly reduced scale.
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