Maps- Introduction
Arguably, the most important thing in land navigation is having a good map. With a good map, you can theoretically identify landmarks, find them on the map and orient the map so you know roughly where you are and what direction to go in order to get to a place. All without a compass. By simply identifying real-life objects on the map, then orienting the map so it aligns with the objects you found, you can theoretically find your way to other points. This is referred to as Terrain Association and is closely tied to Situational Awareness (knowing where you are and what's around you at all times).
The goal of land navigation is to get from point A to point B. The basic thought is:
1) Know where you’re at currently; point A.
2) Turn to a certain azimuth (direction) that points towards your target; point B.
3) Travel a certain distance maintaining that direction and you will find point B.
There are many concepts that repeat during these discussions. That’s intentional to help you understand how these concepts all relate to each other.
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Maps are simply a pictorial or smaller representation of the land/surface of the Earth. They are drawn from the perspective of looking down on the Earth and are drawn to scale. Some symbols are not drawn to scale because they would be too small to visualize on a map.
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The United States was mapped by the US Army map service around 1950 and then field checked by aerial photographs.
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The United States Geological Society (USGS) aerial photographs are updated every 5 to 7 years.
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Maps can tell you five things (the “5 D’s”): Ref "Be an Expert with Map and Compass..."
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Description (name of the map)
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Details (symbols, contours)
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Direction
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Distance
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Designation (names of places)
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This site is setup to follow the five D's when talking about maps and land navigation.​
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Someone who makes maps is called a cartographer.
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There are many types of maps.
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Simple maps are referred to as planimetric; they show a flat plane but not elevation (hills, mountains, or valleys). When you see the word “planimetric” think “plane”, as in flat. An example is a road map.
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Maps that show elevation and surface details are called Topographic maps.
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Some topographic maps represent elevation with contour lines.
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Some topo maps represent elevation with shading. Shaded topographic maps are called relief maps. "Relief" in this sense means that the map shows elevation. Darker shaded areas indicate steeper slopes.
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The most commonly seen orienteering maps are USGS Topographical Maps also called “7 ½ Minute Quadrangle Maps”. These are contour line topographic maps. Quadrangle means 4 angles or 4 sides. A quadrangle (or “quad”) is a square/rectangular section or map. 7 1/2 minutes refers to the area the chart covers in terms of minutes of angle. More on that in "Units" and "Directions."
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Topographic maps show land features (mountains, depressions, hills, valleys, cliffs etc), water (lakes, ponds, streams, etc), and man made features (easy to identify buildings).
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On these maps True North is always “up”. The thin black vertical lines on the left and right sides of the map (and all lines connecting similar longitudes) are always pointing to True North and South. These lines converge at the north and south pole. These vertical lines are lines of longitude (described later).
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Even though I say True North is "up", the proper way to determine True North is to use the declination diagram at the bottom of the map. The arrow that points to the star ★ points to True North. Often the diagram will also have "N" for North, or "TN" for True North. More on that later.
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The lines that are on all four borders that is the edge of the mapped area are called neatlines.
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Directions you find directly from a topographic map are always based on True North being 0° and are referred to as "true" azimuths. To convert them to a compass (which uses Magnetic North for 0°) and are referred to as "magnetic" azimuths, you need an additional step that we’ll talk about later. To distinguish between them, you should say "true" or "magnetic" after the azimuth: like "89° True" or "250° Magnetic."
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Maps of water bodies are referred to as "charts". Maps of items important to air travel (like large distinct objects, airports, and navigational routes) are referred to as "aeronautical charts."
