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Monday, February 15, 2010

Urban Survival Skills – Map Reading Basics #1

Even if the Urban Survivor does not plan on having to move on foot over ground to get to the Safe Location, having a rudimentary ability to read maps and navigate is essentially a basic skill.

The crew here at www.urbansurvivalskills.com is going to post a few basic map reading lessons in order to facilitate the fledging Urban Survivor.

Every topographical map should have what is called Marginal Information
and should include Map Identification information such as Map Sheet Name and possibly a catalog number.

Other Marginal Information, depending upon type of map, may include:

Index to Boundaries. Shows County and State boundaries that occur within the map area.

Adjoining Sheets Diagram. Depicts the map sheets by Map Sheet Name and/or Number that border this map sheet.

Elevation Guide. Provides a means of rapid recognition of major landforms and their elevation range.

Declination Diagram. This diagram depicts the angle differences between True, Grid and Magnetic North. What is NORTH on a map is somewhat different from the magnetic NORTH shown by a compass – this diagram shows you how to convert from one to the other.

Bar Scales. These are rulers used to determine map distance to ground distance. On the 1:50,000 maps that we will be using the scales are in Kilometers, Statute Miles and Nautical Miles.

Contour Interval Note. Shows vertical distance between adjacent contour lines on the map.

Grid Zone and 100,000 meter Square Identification. Found on military maps using the Military Grid Reference System (MGRS) as opposed to Universal Transmercator (UTM) or Geographic Coordinates (Latitude and Longitude) which is the coordinate systems for most other maps including the excellent US Geological Survey maps.

Legend. This information contains the symbols and their descriptions.

The Map should be in colors which are used to designate various things such as:

Black. Man-made features such as buildings and roads.

Reddish-Brown. Relief features, terrain features and contour lines.

Blue. Water such as lakes, rives, streams and drainage.

Green. Vegetation such as orchards, woods, etc.

Red. Populated areas, boundaries - mainly on older maps.

Other. Sometimes other colors are used to show special information and objects. These will be listed in the Legend portion of the marginal information as well.

The next Map Reading Lesson will focus on identification of natural terrain features.

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