The intricate details on a topographic map can be befuddling, even frustrating, if you are learning while out in
backcountry. But once you get familiar with markings and symbols, reading maps will become a friendly aid, rather than a dreaded assignment. Topographic Maps Grid System
Lines of latitude run parallel to equator (east and west), and lines of longitude run perpendicular to equator (north and south). These lines form a pattern of squares across surface of earth like a checker board.
One square, formed by lines of longitude and latitude, measures 90 degrees x 90 degrees. Degrees are further subdivided into minutes and seconds.
• 1 degree = 60 minutes • 1 minute = 60 seconds
The important thing to understand, when we look for a topographic map for our hiking adventures, is that it will be located within this larger context of degrees, minutes, and seconds. Fortunately, it will also, usually, be identified with a place name.
An alternative method of notation within Geographic Coordinate System is decimal degree system. In decimal degree system, minutes and seconds are replaced by a percentage of a degree, expressed as a decimal up to four places long. It is often used for Geographic Information Systems (GIS) applications,
Topographic Maps Scale Explained
A topographic map lists its scale in margin or legend. The scale is relationship between distances on a map and corresponding distance on ground. For example, a map with a scale of 1:50,000 means that 1 unit of measurement on map equals 50,000 equivalent units on ground.
Units can be in inches, feet, centimeters, or meters, depending on what scale map you are looking at and what measuring system country uses. Most USGS maps are 1:24,000, also known as 7 ˝ minute maps. On this map, 1 inch = 24,000 inches on ground. In Canada, most hiking maps are 1:50,000 scale, where 1 cm = 50,000 cm on ground.
A small scale map (ex. 1:100,000) covers a large area; it shows less detail with fewer features. A large scale map (ex. 1:10,000) covers a small area; it shows great detail and small features. A 1:2,500, large scale map would show individual houses and street lights.
Topographic Maps Symbols and Colors
The symbols and colors used on Topographic maps are fairly straight forward:
• Black - man-made, “cultural,” features such as roads, buildings, etc. It is also used to show geographical names (toponymy), certain symbols, geographic coordinates, precise elevations, border information and surround information.
