Maps and Location Systems
PHYSICAL GEOGRAPHY 101

What is a map?

Graphic representation of a given area - a drawing
Can cover a large area
Can cover a small area
Can be detailed, generalized or cartooned

Language of Maps: Map Reading

Maps contain large amounts of information but unless you can read that information it won't do you any good

Problem: How do we represent the surface of a sphere on a map?

1. Globes
- direct representation - no distortion
- limited in size
- not easily transported or moved
2. Flat Sheets
Problem with a flat sheet is that it is not possible to flatten a sphere without distorting the surface
- Undevelopable geometric figure -cannot be flattened without distortion.
- Developable geometric figure- can be flattened without distortion: cylinder, cone, plane

Map Projections

Projection of the surface of a sphere onto a developable surface
- imagine a lightbulb at the center of the sphere and the lines on the sphere casting shadows on the surface of a developable figure

Plane Projections

a. Plane in contact with one point of the sphere
b. Polar Projection is most common type

Conic Projections

a. Cone apex is located directly above the pole
b. best for mid-latitude maps

Cylindrical Projections

a. Cylinder oriented parallel to axis
b. Mercator Projection is most well known
- developed by Gerhardus Mercator, Flemish cartographer. It has the property that any straight line drawn on the surface has a constant compass bearing - used in naval navigation

Interupted and Condensed Projections

a. broken surface
b. condensed - unneeded parts are omitted.

Map Location Systems

Global System - Longitude and Latitude

1. Longitude lines - "Meridians" - "Great Circles"
- north-south lines on the globe - all intersect at the North and South Poles
- measured in degrees East and West of the Prime Meridian
2. Latitude lines - "Parallels"
- East-West lines on the globe
- measured in degrees North and South of the Equator

Local Location System

1. Public Land Survey System
- Township and Range

Basic Map Information

All maps should contain the following information

Title - clearly and concisely describes the map location
Date - indicates the date of publication or revision
Location - Longitude and Latitude; Public Land Survey System; Inset Map.
Directional Orientation - Compass direction - if no compass direction is given, the standard convention is that north is at the top of the map
Legend - Information on the symbols used on the map
Scale
a. Ratio Scale -ex. 1:24,000 - 1 inch on the map = 24,000 inches on the ground
b. Bar Scale - allows direct measurement of the ground distances

Some of the Major Types of Maps

• Physiographic
• Topographic
• Geologic
• Environmental - Landscape, Vegetation, Precipitation, Climatic, etc.
• Geographic Maps - Political, Country, State, Local, City, Highway, Road
• Statistical - Population, Economic

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Notice: The material contained within these web pages only applies to those courses and sections taught by Richard Harwood. Unless otherwise noted, all images and graphics contained within are the property of Richard Harwood and may only be reproduced with permission from the author.