Basic Compass Reading & Land Navigation

Saddle

A depression or pass in a ridgeline.

Landmark

A feature in the landscape which can be readily recognized; anything from a prominent tree or rock, to a church or a lake.

Mesa

A flat-topped mountain with steep sides.

Azimuth

A horizontal angle measured clockwise from north or south.

Legend

A key accompanying a map which shows information needed to interpret that map.

Spinning Dial

A large dial that is not too hard to spin and is marked from 0 to 360 degrees is most useful.

Map

A line drawing, to some scale, of an area of the earth's surface. It shows objects and features by conventional signs.

Graphic Scale

A line marked off on a map which compares map distances to the ground distance in "different" units of measurements.

Contour

A line on a map or chart indicating elevation in feet, and connects all points of the same height above sea level.

Depression

A low place in the ground having no outlet for surface drainage.

Triangulation

A method of determining the location of an unknown point by using the laws of plane trigonometry.

Hill

A naturally occurring mass of earth material whose crest or summit is at a lower elevation than a mountain.

Photomap

A reproduction of an aerial photograph upon which grid lines, marginal data, place names, route numbers, important elevations, boundaries, and approximate scale and direction have been added.

Representative Fraction

A scale that expresses the ratio of the map distance to the ground distance in 'SAME' units of measurements.

Hachures

A series of short, nearly parallel lines used in map making to represent a sloping surface.

Valley

A stretch of low land lying between hills or mountains which are sometimes occupied by a stream.

Degree

A unit of angular measurement equal to one-360th part of the circumference of a circle.

Township

An area of land divided by township lines and range lines which is approximately 36 miles square.

Section Area

An area of land one mile square and containing 640 acres, more or less.

Base Line

An imaginary line on the ground running east-west (horizontal) measured with special accuracy to provide a base for surveying.

Principal Meridian

An imaginary line on the ground running north-south which is accurately laid out to serve as the reference meridian in land surveys.

Compass

An instrument used for showing direction, consisting of a magnetic needle swinging freely on a pivot and pointing to magnetic north.

Latitude

Angular distance, measured in degrees, creating imaginary lines circling the earth's globe.

Longitude

Angular distance, measured in degrees, creating imaginary lines extending from north pole to the south pole which identify geographical positions on the earth's globe.

Magnetic Bearing

Bearing by magnetic north rather than true north.

True Bearing

Bearing by true north rather than magnetic north.

Pink Areas

Built up areas, cities and dense buildings, civilization.

Red Lines

Classifies cultural features, such as populated areas, main roads, and boundaries, on older maps.

Button

Commonly carried in survival kits or on jacket lapels. Accuracy varies but can be generally good.

Pace

Defined as the average length of two natural steps.

UTM Grid

Developed by the military, the UTM grid (Universal Transverse Mercator grid) has the advantage of being able to depict most places on the globe as true rectangles or squares.

Grid North

Direction towards north pole along grid lines on a map projection.

U.S.G.S. (United States Geological Survey)

Engaged in topographic and geologic mapping and in collection of information about the public lands.

Brown Lines

Identifies all relief features and elevation such as contours on older edition maps and cultivated land on red-light readable maps.

Blue Areas

Identifies hydrography or water features such as lakes, swamps, rivers, and drainage.

Green Areas

Identifies vegetation with military significance such as woods, orchards, and vineyards.

Black Lines

Indicates cultural (man-made) features such as buildings and roads, surveyed spot elevations, and all labels.

Map Scale

Indicates the ratio or proportion of the horizontal distance on the map to the corresponding horizontal distance on the ground.

Ridge

Long narrow elevation of land; a steep slope or a similar range of hills or mountains.

Back Bearing

Measured from the object to your position. It is the exact opposite of a direct bearing.

Baseplate

Most common sold at most outdoor stores. Excellent for land navigation, orienteering, learning map and compass.

Cardinal Positions

North, south, east, west; used for giving directions and information from the ground or air in describing the fire.

Lensatic

Popularized by military. Used for calling in artillery and general orienteering. Great for intended purpose.

Purple Areas

Revisions or updated Information

Planimetric Map

Shows the positions of features without showing the elevations of all hills and valleys of the land.

Topographic Map

Shows the positions of features, and also represents their vertical position in a measurable form.

Magnetic Declination

Simply the angular difference between True North and Magnetic North.

Declination

The difference in degrees between true north and magnetic north.

Magnetic North

The direction toward which a magnetic needle of a compass points.

Slope

The ratio between the amount of vertical rise of a slope and horizontal distance, expressed in percent.

Luminous North Box

This is the dial's indicator used to box the needle. To "box the needle" means to hold the compass horizontally and rotate it until the needle's north end comes to rest inside the luminous north box.

Base Plate

Used as a ruler for measuring distances, or in combination with the spinning dial, as a protractor for measuring map angles.

Sighting Mirror

Used in conjunction with the fixed sight to take bearings of distant objects, or to "shoot" an azimuth, meaning to determine a specific compass direction.

Fixed Sight

Used whenever you need direction measurements as accurate as 2 degrees.

Luminous Needle

Useful for night navigation. When charged with a flashlight or other light source, it glows for 10 or 15 minutes, allowing you to navigate without a light.

Direction of Travel Indicator

When the spinning dial is set to your intended course, and when the needle is within the luminous north box, this indicator points the way.