September 19, 2012
- "The end result and final goal of all geographic investigations, explorations, and
surveys is the depiction of the Earth's surface: the map. The map is the basis for
geography. The map shows us what we know about our Earth in the best, clearest, and
most exact way."
- August Petermann
- Map: a geographic representation of a part of the Earth's surface
- Essential quality of maps - they are representations of a locality or place, i.e.,
maps are locational images
(1) What do maps tell us?
(2) How should we read maps?
(3) Why are maps so important to geographers?
The Elements of Maps
1. The Global Grid
- Key reference points which enables us to determine "where" something
is located on the Earth
- North Pole
- South Pole
(Each of these is given in nature)
- Prime Meridian
(Agreed upon by cartographers as the meridian of longitude which asses
through the Royal Observatory at Greenwich, England)
- Given these four reference points and the fact that a circle (Earth) contains 360
- The distance between the poles is 180 degrees, and the distance between the
equator and each pole is 90 degrees.
(1) Measure of distance north and south of the equator
(2) Parallels of latitude run east-west
(3) All parallels of latitude are parallel to each other and to the equator
(4) Parallels decrease in length close to the poles
(1) Measure of the angular distance east/west of the Prime Meridian
(2) Meridians of longitude run north-south
(3) All meridians are of equal length, and each meridian is one-half the
length of the Equator
(4) All meridians converge at the poles
- Combining lines (parallels) of latitude with lines (meridians) of longitude, we
get a grid in which:
(1) Meridians and parallels intersect at right angels
(2) The scale (see below) on the surface of the earth is the same in every
direction* * Only the globe itself retains these characteristics. When the grid is projected onto a flat
surface, distortion occurs.
2. Scale: The relationship or ration between the size of a feature on a map and the same
feature on the Earth's surface.
- Example: A 1:50,000 scale means that 1 inch on the map represents
50,000 inches on the Earth's surface
- (1) The smaller the scale, the larger the area being represented on
the map? (Why is this the case?)
- (2) A smaller scale map is more generalized (less detailed) than a
large scale map (which is more detailed)
Types of map scales:
(1) Graphic line scales
(2) Verbal scale - "1 cm on the map represents 1km on the Earth"
(3) Representative fraction 1:50,000
- Critical challenge facing cartographers: How to display the curved
surface of the earth on a flat sheet of paper?
- Map Projectio