Topographic Maps 101

The intricate details on a topographic map can be befuddling, even frustrating, if you are learning while out in the backcountry. But once you get familiar with the 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 the equator (east and west), and lines of longitude run perpendicular to the equator (north and south). These lines form a pattern of squares across the surface of the 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 the Geographic Coordinate System is the decimal degree system. In the 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 the margin or legend. The scale is the relationship between distances on a map and the corresponding distance on the ground. For example, a map with a scale of 1:50,000 means that 1 unit of measurement on the map equals 50,000 equivalent units on the ground.

Units can be in inches, feet, centimeters, or meters, depending on what scale map you are looking at and what measuring system the country uses. Most USGS maps are 1:24,000, also known as 7 ½ minute maps. On this map, 1 inch = 24,000 inches on the ground. In Canada, most hiking maps are 1:50,000 scale, where 1 cm = 50,000 cm on the 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.

? Blue ?water, lakes, rivers, streams, etc. The names of bodies of water and water courses are also shown in blue, as are magnetic declination and UTM (Universal Transverse Mercator) grid information.

? Brown - contour lines, contour elevations, spot elevations, sand.

? Green - areas with substantial vegetation like a forest, orchard, or vineyard

? Grey - used on the back of the map where the different symbols and a glossary of terms and abbreviations can be found.

? Orange - unpaved roads and unclassified roads and streets.

? Purple - features added to the map since the original survey. These features are based on aerial photographs but have not been checked on land.

? Red - major highways; boundaries of public land areas. A red tint is used to show an urban development.

? White - areas with little or no vegetation; also used to depict permanent snowfields and glaciers

Topographic Maps Glossary

? Bearing - Angular direction expressed in degrees.

? Contour Lines ? A line on a map joining points of equal elevation. These lines are used to illustrate relief on a map.

? Distortion - The difference in shape between the actual curved surface of the earth and the flat representation of a topographic map.

? Grid - A system of horizontal and vertical lines that provide coordinates for locating points on an image.

? Magnetic Declination - The angle between magnetic north and true north, expressed in degrees and minutes, east or west from true north.

? Magnetic North - The direction your compass needle points.

? Projection - A method by which the curved shape of the earth is represented on a flat surface, overcoming distortion.

? Relief ? The variations in elevation of the earth's surface.

? Scale ? The relationship between distance on a map and the corresponding distance on the ground. For example, a map with a scale of 1:50,000 means that 1 unit of measurement on the map equals 50,000 equivalent units on the ground.

? Topographic Map ? An illustration of the earth's different elevation levels by means of contour lines. They present both natural and manmade features.

? True North - Direction of the northern rotational axis of the earth ? the North Pole.

Outdoors Adventurer, Writer and Webmaster Will Robertson lives with his family in Little Rock, Arkansas.

Explore the best hiking vacations and gear on the planet at: http://www.hiking-vacations-and-gear.com

Related News

Outdoors Report: Steelheaders getting in some early punches - Seattle Post Intelligencer Outdoors Report: Steelheaders getting in some early punches Seattle Post Intelligencer -5 hours ago By GREG JOHNSTON The winter steelhead season is well under way, not spectacular so far but definitely early and spread throughout the traditional streams of ... Outdoors enthusiasts still want trucks, SUVs - The Flint Journal - MLive.com Outdoors enthusiasts still want trucks, SUVs The Flint Journal - MLive.com, MI -Dec 3, 2008 ... about those of us who do drive trucks and SUVs. Dave Graham is an outdoors writer for The Flint Journal. He can be reached at (810) 766-6306 or by e-mail. How to Tame a Cat With a Taste for the Outdoors - Washington Post How to Tame a Cat With a Taste for the Outdoors Washington Post, United States -14 hours ago He has had a taste of the outdoors and wants to go out again. We regularly have to get chairs to reach him when he jumps onto curtain rods and bookcases, ... Outdoors by Wayne Baughman - Pittsfield Pike Press Outdoors by Wayne Baughman Pittsfield Pike Press, IL -1 hour ago The tally is in for the first portion of the firearms deer season that was held Nov. 21,22, and 23. Statewide hunters took 71894 deer, which is a decline of ... Fisheries biologist hatches plan in dark of Marquette ParkJoliet Herald News all 3 news articles Great Outdoors Almanac - Green Bay Press Gazette Great Outdoors Almanac Green Bay Press Gazette, WI -12 hours ago A few anglers are starting to fish frozen portions of rivers and harbors, but it's still slushy, open water throughout much of Green Bay. ... Outdoors briefs - Dallas Morning News Outdoors briefs Dallas Morning News, TX -20 hours ago By RAY SASSER Outdoors Writer rsasser@dallasnews.com With the 2009 Panhandle pheasant season looming Saturday, Texas Parks and Wildlife is asking hunters ... Outdoors notebookAustin American-Statesman all 3 news articles Gift giving – the outdoors versus the non-outdoors - Evening Sun (subscription) Evening Sun (subscription) Gift giving – the outdoors versus the non-outdoors Evening Sun (subscription), NY -6 hours ago Usually they were given by a non-outdoors person who had little or no knowledge about the lifestyles of avid outdoors people. Often, the gift idea came from ... Outdoors calendar - Green Bay Press Gazette Outdoors calendar Green Bay Press Gazette, WI -12 hours ago Listings are subject to change, so call to check availability. All telephone numbers are area code 920 unless otherwise noted. To submit a notice, ... GI Janes get outdoors - News & Observer News & Observer GI Janes get outdoors News & Observer, NC -14 hours ago Deanna Lampley, MWR business manager for outdoor recreation, told the group of 29 participants the day was designed to show that the outdoors is for ... Want a holiday gift for an outdoors lover? Here are some ideas - Dallas Morning News Want a holiday gift for an outdoors lover? Here are some ideas Dallas Morning News, TX -20 hours ago It's not long until Christmas. Here are some gift ideas, most of them under $100, for the sportsman on your shopping list: • Frogg Toggs Pro Action rain ...