MAPS, SCALES & PROJECTIONS
Map - pictorial representation of the geographic location of selected surface features at a
reduced scale
- generalized view of an area, usually some portion of the Earth’s surface, as seen from
above & greatly reduced in size
Cartography - art of mapmaking
Map Essentials
1) title - brief summary of the map’s content or purpose
2) date - either date information was gathered or the date of publication or both
3) legend - explanation of the symbols used
4) scale - relationship between length measured on the map & the corresponding distance
on the ground
5) direction - normally shown by means of a geographic grid (N-S & E-W) with the
addition of a straight arrow pointing northward
a) geographic north - true north
b) magnetic north - direction which a magnetic compass needle points
magnetic declination - angle between true north & magnetic north
6) location - use of a geographic grid system
Map Scale - ratio of the distance on a map to that in the real world; expressed as:
a) fractional scale (representative fraction, RF) - expresses the ratio with a : or /
b) graphic scale (bar scale) - uses a line marked off with graduated distances
c) written scale - states the ratio in words
Map Scale Sizes - depends on the ratio described; the greater the denominator in a
fractional scale, the smaller the scale
a) Small - 1:3,168,000 (1 in = 50 mi)
b) Medium - 1:125,000 (1 in = 2 mi)
c) Large - 1:24,000 (1 in = 2000 ft)
Map Projection - reduction of a spherical globe onto a flat surface
Globe Properties
1) all meridians are equal in length
2) all meridians converge at the poles
3) all lines of latitude (parallels) are parallel to the equator & to each other
4) parallels decrease in length as the poles are approached
5) meridians & parallels intersect at right angles
6) the scale on the surface of the globe is the same everywhere in all directions
The 4 main properties of maps - area, shape, distance, direction - are distorted in different
ways & to different degrees by various projections. So the projection must be determined by its
intended use