Map Reading Class ROTC

Bar Scales

Bar scales are located in the center of the lower margin. They are rulers used to convert map distance to ground distance. Maps have three or more bar scales, each in a different unit of measure.

Colors used on the map

Black: Man-made features Blue: Water features Brown: Relief features and elevation on older or red-light readable maps Green: Vegetation Red: Man-made features Red-Brown: Cultural features and non-surveyed spot elevations Other: Occasionally other colors may be used to show special information and - if used - will be noted in the marginal information

three minor terrain features

Draw Spur Cliff

5 major terrain features

Hill Valley Ridge Saddle Depression Hidden Valley Ranch Salad Dressing

Adjoining Sheets Diagram

Maps at all standard scales contain a diagram that illustrates the adjoining sheets. . The diagram usually contains nine rectangles, but the number may vary depending on the locations of the adjoining sheets. All represented sheets are identified by their sheet numbers. Sheets of an adjoining series, whether published or planned, that are at the same scale are represented by dashed lines. The series number of the adjoining series is indicated along the appropriate side of the division line between the series.

Ridgline

Not the same as a ridge is a line of high ground with changes in elevation along its top and low ground on all sides, also composed of natural or man-made terrain features

Grid Reference Box

The grid reference box is normally located in the center of the lower margin. It contains instructions for composing a grid reference.

Sheet Name

The sheet name is found in bold print at the center of the top and in the lower left area of the map margin

Sheet #

The sheet number is found in bold print in both the upper right and lower left areas of the margin, and in the center box of the adjoining sheets diagram, which is found in the lower right margin. It is used as a reference number to link specific maps to overlays, operations orders, and plans.

Contour lines

a line on a map joining points of equal height above or below sea level.

Supplementary lines

appear as dotted lines, indicating flatter terrain

Index lines

are the thickest contour lines and are usually labeled with a number at one point along the line. This tells you the elevation above sea level.

Intermediate lines

are the thinner, more common, lines between the index lines. They usually don't have a number label. Typically one index line occurs for every five intermediate lines.

2 supplemental terrain features

cut and fill

saddle

dip or low point between two areas of higher ground if you are inside the saddle there is high ground on 2 opposite directions and lower ground in the other 2 directions normally represented as an hour glass on a map

depression

is a low point in the ground or a sink hole Usually only depressions that are equal to or greater than the contour interval will be shown. On maps, depressions are represented by closed contour lines that have tick marks pointing toward low ground.

spur

is a short continuous sloping line of higher ground normally protruded out from the side of the ridge and between two draws on a map, the contour lines are v or u shaped pointed away from higher ground and are wider than draws

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.

draw

is a stream course that is less developed than a valley no level ground and very difficult to maneuver in if you are standing in a draw, the slope of the ground is pointed upwards in 3 directions and to lower ground in the other direction (initial formation of a valley) can be v or u shaped pointing towards higher ground and the contour lines tend to be a lot more narrower than a spur

valley

is a stretched groove in the land that is usually formed by streams or rivers usually begins with high ground on 3 sides and running water that flows through it water flows from higher to lower ground contour lines forming a valley are either u or v shaped, to understand where the water is flowing, an upside u or v shape points upstream or toward higher ground

hill

is an area of high ground from the hilltop the ground slopes down in all directions shown on a map by contour lines forming concentric circles the inside of the smallest circle is the hill top

Special Notes

is any statement of general information that relates to the mapped area. It is normally found in the lower right margin. For example: This map is red-light readable.

Contour Interval Note

is found in the center of the lower margin normally below the bar scales. It states the vertical distance between adjacent contour lines of the map. When supplementary contours are used, the interval is indicated.

Legend.

is located in the lower left margin. It illustrates and identifies the topographic symbols used to depict some of the more prominent features on the map. The symbols are not always the same on every map. Always refer to the legend to avoid errors when reading a map.

Declination Diagram

is located in the lower margin of large-scale maps and indicates the angular relationships of true north, grid north, and magnetic north. In recent edition maps, there is a note indicating the conversion of azimuths from grid to magnetic and from magnetic to grid next to the declination diagram.

cut (in)

man-made feature resulting from cutting through raised ground usually to form a level bed for a road or rail road track shown on a map when they are at least 10 ft high and contour lines along the cut line, tick marks will be show pointing inwards

fill (out)

man-made feature resulting from filling a low area to form a level bed for a road or railroad track, tick marks on the contour line point outwards towards lower ground

cliff

vertical feature where the slope is so steep that the contour lines on the map converge to one with either tick marks on the last contour line pointing out to lower ground or contour lines shown very close together