LAND NAVIGATION

Marginal Information
Map Instructions
Top Margin series name -is found in the upper margin. It usually includes a group of similar maps at the same scale or the same sheet lines designed to cover a particular geographical area. The name given a series is that of the most prominent areas. edition number- represents the age of the map in relation to other editions of the same map and the agency responsible for its production.
Scale- note indicates the relative value of distance on the map compared to distance on the ground. A map with the scale of 1:50,000 means that 1 inch on the map equals 50,000 inches on the ground or 1,270 meters. Different map scales indicate different degrees of topographical detail. As the ratio increases, map detail decreases.
For example, a map with a scale of 1:25,000 is more detailed than a map with a scale of 1:50,000. With a ratio of 1:25,000, 1 inch on the map equals less area on the ground than a map with ratio of 1:50,000. series number- is a sequence reference expressed either as a four-digit number (1125) or as a letter followed by a three or four-digit number (M556; N3341). It is found in both the upper right margin and the lower left margin. sheet name- is found in bold print at the center of the top and in the lower left area of the map margin. A map is generally named for the settlement contained within the area covered by the sheet, or for the largest natural feature located within the area at the time the map was drawn. sheet number- is used as a reference number for that map sheet. It is found in the upper right margin and the lower left margin.

Bottom Margin contour interval note- states the vertical distance between adjacent contour lines on the map. When supplementary contours are used, the interval is indicated.
In recent edition maps, the contour interval is given in meters instead of feet. This note is found in the center of the lower margin normally below the bar scales
Legend- illustrates and identifies the topographic symbols used to depict some of the more prominent features on the map, such as railroad tracks, buildings, and swamps.
The symbols are not always the same on every map. Always refer to the legend to avoid error when reading a map. The legend is located in the lower left margin
Bar scales- are used to convert map distance to ground distance. Maps may have three or more bar scales, each in a different unit of measure.
Exercise care when using the scales, especially in the selection of the unit of measure. The bar scales are located in the center of the lower margin

Lower Right Margin declination diagram- indicates the difference between true north, grid north, and magnetic north.

This value is shown in degrees. You will use the diagram when converting a magnetic azimuth shown on your lensatic compass dial to a grid azimuth on your map. You can also use it to convert a grid azimuth to a magnetic azimuth. elevation guide- is a miniature characterization of the terrain shown. The terrain is shown by bands of elevation (contours), spot elevations, and major drainage features.
The elevation guide helps you rapidly identify major land forms. It is normally found in the lower right margin. On most maps, the higher elevations are represented by a darker color
Boundaries- diagram appears in the lower or right margin of all sheets. This diagram, which is a miniature of the map, shows the boundaries that occur within the map area, such as county lines and state boundaries. adjoining sheets- diagram that illustrates how the map connects to other maps. All represented sheets are identified by their sheet numbers.
In this example, the map number 2083-3 is adjacent to 2083-4. So if you are navigating north and reach the north boundary of the 2083-3 map, you can use the 2083-4 map to continue. This diagram usually contains nine rectangles, but the number may vary depending on the locations of the adjoining sheets. The diagram is found in the lower right margin of all map sheets

Map Colors
Black- depicts cultural (man-made) features such as buildings, transportation features, surveyed spot elevations, and all labels.
Red/Brown- is used to identify cultural features, all relief features, non-surveyed spot elevations, and elevation (such as contour lines on red-light readable maps).
Blue- indicates water features such as lakes, swamps, wetlands, rivers, and streams

Green- indicates vegetation with military significance such as woods, orchards, and vineyards
Brown- identifies all relief features and elevation such as contours on older edition maps and cultivated land on red-light readable maps.
Red- classifies cultural features such as populated areas, main roads, and boundaries (on older maps).

Reading Terrain Features
Affect on Operations
Elevation (Contour Lines)
Contour lines are the most common method of showing relief and elevation on a standard topographic map.
A contour line represents an imaginary line on the ground, above or below sea level. All points on the contour line are at the same elevation. The elevation represented by contour lines is the vertical distance above or below sea level.
The three types of contour lines used on a standard topographic map are shown here:
Index
Starting at zero elevation or mean sea level, every fifth contour line is a heavier line. These are known as index contour lines.
Normally, each index contour line is numbered at some point. This number is the elevation of that line
Intermediate
Intermediate contour lines fall between the index contour lines.
These lines are finer and do not have their elevations given. There are normally four intermediate contour lines between index contour lines.
Supplemental
Supplemental contour lines resemble dashes. They show changes in elevation of at least one-half the contour interval.
These lines are normally found where there is very little change in elevation, such as on fairly level terrain

Hill, Ridge, and Saddle
Hill- is an area of high ground. From a hilltop, the ground slopes down in all directions. A hill is shown on a map by contour lines forming concentric circles
Ridge- is a sloping line of high ground. Contour lines forming a ridge tend to be U-shaped or V-shaped. The closed end of the contour line points away from high ground
Saddle- is a dip or low point between two areas of higher ground. On a map a saddle is normally represented as an hourglass

Spur, Draw, and Valley

Spur- is a short, continuous sloping line of higher ground, normally jutting out from the side of a ridge. A spur is often formed by two roughly parallel streams cutting draws down the side of a ridge. The ground will slope down in three directions and up in one.

Draw- is a less developed stream course than a valley. In a draw, there is essentially no level ground and, therefore, little or no maneuver room within its confines. The contour lines depicting a draw are U-shaped or V-shaped, pointing toward high ground.
Valley- is a stretched-out groove in the land, usually formed by streams or rivers.
Cut, Depression, and Cliff

Cut- is a man-made feature resulting from cutting through raised ground, usually to form a level bed for a road or railroad track
Depression- is a low point in the ground or a sinkhole. It could be described as an area of low ground surrounded by higher ground in all directions, or simply a hole in the ground
Cliff - is a vertical or near vertical feature. It is an abrupt change of the land, when a slope is so steep that the contour lines may converge into one

Plotting Points on a Map
Basic Map Reading Rule

The designation of a point is based on the principle: Read RIGHT then UP.
Always read right on the vertical grid lines then up on the horizontal grid lines

Using a Lensatic Compass
Compass Nomenclature

The compass dial floats free when in use. It is locked in place by closing the eyepiece. It contains two complete circular scales, one in degrees (red scale) and one in mils (black scale). The magnetic arrow is found on the compass dial
The bezel ring holds the upper glass crystal in place. It helps preset a direction for night compass navigation. It contains 120 clicks when rotated fully; each click equals 3 degrees
The cover contains a sighting wire. When closed, it protects the face of the crystal. When at a 90° angle to the other half of the compass, it can be used to sight on objects. The cover includes a graduated straight-edge that is referenced when orienting the map
The thumb loop serves as a retaining device to secure the compass in a closed position. It is used when holding the compass in position for sighting on objects
The black index line is a stationary line used as a reference line for determining direction. When held properly, it identifies the direction the compass is pointing
The sighting wire provides an exact azimuth for objects. It can be used for compass calibration. It is also used with steering marks

The Declination Diagram

True north indicates the direction to the geographic North Pole. True north is marked with a star (*) on the declination diagram
Grid north indicates the direction in which the north-south grid lines of a map are oriented. These may or may not correspond with True or Magnetic North, depending on where you are located in the world
Magnetic north indicates the north direction of your compass reading. It is usually different than true north because the earth’s magnetic field causes the compass arrow to point to a magnetic area around instead of directly at the North Pole. Magnetic north direction will change depending on your geographic location and also with time. Magnetic north is marked with a half arrowhead
The G-M angle is the difference between grid north and magnetic north shown in degrees. You will add or subtract this value from the magnetic or grid azimuth when converting from one north direction to another.
Deliberate Offset

A deliberate offset is a planned magnetic deviation to the right or left of an objective. Use it when the objective is located along or in the vicinity of a linear feature such as a road, stream, and so forth. Because of errors in the compass or in map reading, the linear feature may be reached without knowing whether the objective lies to the right or left.
A deliberate offset by a known number of degrees in a known direction compensates for possible errors and ensures that upon reaching the linear feature the user knows whether to go right or left to reach the objective. Ten degrees is an adequate offset for most tactical uses.

Elements That Can Impair the Performance of a Compass
Inspections
You should conduct a detailed inspection whenever you use a compass.
Your inspection should include checking: * The floating dial to ensure that the glass and crystal parts are not broken * The numbers on the dial are legible * The floating dial does not stick * The sighting wire is straight * The bezel ring produces distinct clicks when turned
You should also periodically check the compass's accuracy at a declination station. If your compass varies more than three degrees you should not use it
The lensatic compass is built to detailed specifications developed to increase its serviceable life. Adherence to a very simple maintenance regimen will significantly increase the life of the lensatic compass. Maintenance requirements are as follows: * Rinse in fresh water, especially after exposure to salt water. * Brush off dirt and grime. * Ensure the ridges on the bezel ring are free of dirt. * Check movement of the rear sight to ensure it is free moving